Turn in your graphs and pages 9-12 ONLY

Size: px
Start display at page:

Download "Turn in your graphs and pages 9-12 ONLY"

Transcription

1 CHEM 152 WINTER 2010 POTENTIOMETRIC TITRATIONS Fill-in, Prelab attached (p 12) Name Turn in your graphs and pages 9-12 ONLY LEARNING OBJECTIVES: After completing this experiment, you should feel comfortable: Calibrating a ph electrode to prepare for a potentiometric titration. Titrating a strong acid with a strong base, weak acid with a strong base, and a polyprotic acid with a strong base. Differentiating acid strength by the shape of a titration curve. Using titration data to determine the concentration of an unknown solution of an acid. Identifying equivalence and half-equivalence points on a titration curve. Relating molarity to normality for a polyprotic acid. Determining acid strength/pk a values off of a titration curve. TO EARN YOUR FINAL STAMP: The following items must be completed in lab. You may complete the entire assignment in the lab; this reflects the minimum required to earn your final stamp. Collect and process all data for the titration of HCl with NaOH Collect and process all data for the titration of H 3 with NaOH Determine the concentration of HCl and H 3 from your titration data, and enter the data in the lab computer for the computation of class averages. Determine the pk a1 and pk a2 for H 3, based on your titration curve. Introduction In the experiment today you will be performing a potentiometric titration to determine the unknown concentrations of two acids. In order to perform this titration you will utilize a ph meter, an instrument which allows you to directly measure the strength and concentration of an acid. Discussion ph meters (see Figure 1) operate by measuring the difference in voltage generated between and indicator electrode and a reference electrode. The reference electrode or probe is not sensitive to H + concentration changes and is simply used as a reference point. This electrode produces a constant voltage (E = +0.2 V) which is provided by the following reaction: Hg 2 Cl 2 + 2e - 2Hg Cl - The sensing probe, which is H + ion sensitive, consists of a glass bulb filled with dilute HCl into which is inserted a silver or platinum wire. (See Figure 1) Exp #8 Potentiometric Titrations Rev W10 NF Winter 2010 Page 1 of 12

2 The glass bulb is permeable to H + ions but not to other ions. If the solution into which the electrode is placed is more concentrated than that in the bulb, H + ions will move from the solution into the bulb. The HCl solution inside the bulb will then have an excess of H + ions and will be positive with respect to the solution being measured This potential difference across the glass membrane can be measured then compared to the reference voltage and a ph determined for the measured solution. Quite often the reference and indicator electrodes are combined into one probe called a combination probe or electrode. It operates the same way as the two probes. Method for Determining Concentration In this experiment you will be titrating both a strong monoprotic acid and a weak polyprotic acid with a standardized strong base. You will be adding the standardized base to the acid and measuring the resulting ph. When the volume of base added is plotted on a graph as a function of ph, a titration curve is produced. From this curve it is possible to determine the milliliters of base needed to neutralize the amount of acid present in the solution of unknown concentration. The shape of the titration curve is dependent on the type of acid being titrated (i.e., strong or weak acid). The two situations are described below. Strong Monoprotic Acids Figure 1 When a strong monoprotic acid, such as HCl, is dissolved in water it totally ionizes into H + and Cl - ions. As a strong base, such as sodium hydroxide, is added to the acid solution, the available hydroxide ions combine with some of the available H + ions to form water. If we continue to add base and record the resulting ph, we produce, upon graphing a titration curve similar to that shown in Figure 4. HCl + H 2 O H +1 (aq) + Cl -1 (aq) H + + OH - H 2 O Exp #8 Potentiometric Titrations Rev W10 NF Winter 2010 Page 2 of 12

3 Figure 2 (accessed February 27, 2008) Notice that until we reach the neutralization or end point, the ph of the solution stays nearly constant. We know that ph is a measure of H + ion concentration (ph = log[h + ]). Since our strong acid totally ionizes, we have a large reserve of H + (actually H 3 O + ) ions available in solution to instantly react with any added base. Because we have such a large reserve of H +, the addition of a few milliliters of base will cause only a small change in the total H + ion concentration. We also know that ph + poh = 14. Since any hydroxide ion that is added is immediately neutralized, the ph remains relatively unchanged. Once the neutralization point is reached, however, the available reserve of H + ions is depleted. The concentration of H + drops dramatically, while the concentration of hydroxide ion increases. This causes the ph value to rise. The ph value continues to rise until the ph of the base being added is reached. Once reached, addition of more base has little effect and the ph again becomes relatively constant. It is possible to determine the endpoint for the neutralization reaction, and therefore the base needed to neutralize the acid, simply by extending a line from the vertical portion of the titration curve to the x-axis (see Figure 2). Since we are given the normality of the standard base and the volume of acid used, the normality of the acid can be calculated using the relationship: Weak Polyprotic Acids N acid V acid = N base V base Weak polyprotic acids such as phosphoric acid (H 3 ) do not totally ionize in solution. In fact, most of the phosphoric acid remains as unionized H 3 molecules in solution. The small amount that does ionize exists as a series of equilibrium equations, each of which produce some H + ions. Reaction #1 H 3 H + + H 2 Reaction #2 Reaction #3 H 2 H 2 H + + H 2 H Ka 1 = [H 2PO 4 ][H + ] = [H 3 ] Ka 2 = [HPO 2 4 ][H + ] = [H 2 PO 4 ] Ka 3 = [PO 3 4 ][H + ] = [HPO 2 4 ] Exp #8 Potentiometric Titrations Rev W10 NF Winter 2010 Page 3 of 12

4 We can also perform a potentiometric titration on H 3 (see Figure 3). Note in this graph that the ph value slowly increases and that the ph transitions through the end points of the acid are not abrupt but instead are gradual. The third equivalence point is not observed. Note the volumes (and relationships) at the equivalence points. Figure 3 ½ equivalence points: the volume between (½ way between each eq. pt) If the volume to get to the first eq. pt = ml then the ½ eq. pt = 5.00 ml. At this point, ph = pka 1. If the volume to get to the second eq. pt = ml then the ½ eq pt = ( ml)/2 = ml. At this point, ph = pka 2. On this graph, ph = pka 1 = 1.9 and ph = pka 2 = 7.3 Exp #8 Potentiometric Titrations Rev W10 NF Winter 2010 Page 4 of 12

5 When we titrate H 3 with a strong base (i.e., NaOH), the following reactions would occur. Or, more accurately, H 3 + NaOH NaH 2 + H 2 O NaH 2 + NaOH Na 2 H + H 2 O Na 2 H + NaOH Na 3 + H 2 O H 3 H + + H 2 NaOH (aq) NaH 2 + H 2 O Where there is no large readily available reserve of H + ions as were present with the totally ionized strong acid, there are three sources where H + ions can be obtained as needed. We have shown that the weak polyprotic acids exist as a series of equilibrium equations. If we shift the equilibrium out of balance, the systems will adjust to reestablish the equilibrium. When the available H + is used to neutralize added base, some unionized acid from each of the three equilibrium equations must ionize to reestablish the equilibrium of the hydrogen ion to near the original value. Since the [H + ] is changing very little, the ph also changes very little. Mixtures of weak acids and their salts stabilize hydrogen ion concentration upon addition of small amount of base by shifting the various equilibrium equations. This is also known as buffering the solution. The size of the ionization (equilibrium) constant is a measure of the degree of ionization. The larger the value, the greater the ionization. For this reason, K 1 is going to supply more H + ions than is K 2 or K 3. Therefore, as the sodium hydroxide is added, reaction #1 will provide more equilibrium concentrations of H + than will reaction #3. Reaction #1 will then be used up first (i.e., its endpoint will be reached first). We do not, however, get a sharp vertical rise at the endpoint as we did with the strong, monoprotic acid. This is because reactions #2 and #3 are still helping to moderate the change in [H + ] and thus, the ph. After the H + from reaction #1 is used, the ph slowly rises to the H + ion value that can be supplied by the equilibrium reactions #2 and #3. Finally, after all H + from reaction #2 is used, we see a third rise in ph. However, because of the very small size of K 3 it is often difficult to obtain an accurate measurement for the titration of reaction #3. You will be asked to perform a potentiometric titration of both HCl and H 3 using the strong base, NaOH, in this experiment. Exp #8 Potentiometric Titrations Rev W10 NF Winter 2010 Page 5 of 12

6 Experimental The standardized base and stir bars can be found on the reagent bench. The magnetic stir plates are under the middle hood. The unknown acids will be in burets for you to use. Measure out about 20 ml and record the volume to the nearest ±0.01 ml. Refill the burets from the bottles/transfer beakers beside the apparatus. The ph electrodes and interfaces are next to the computers CAUTION: Do not spill liquids on the computer or interfaces. Put your set-up together carefully. Place magnetic stir plates as far away from the monitors as possible. PROCEDURE General description- You will be doing two titrations using a ph electrode as a sensor and typing in the volumes you read on the buret. For each acid, HCl and H 3, you will determine the volume at each equivalence point and calculate the molarity for that acid. You must calibrate the electrode before you begin. Technique Tip: Rinse the electrodes between solutions by dipping them into a beaker of distilled water or use a wash bottle to rinse the solution on the electrode into a waste beaker. Setting up the computer: 1. Obtain and wear goggles. Set up the equipment as shown in Figure 4 with the electrode attached to the ph amplifier. Instead of the ph meter you will have your computer, interface and ph amplifier. 2. At the computer, open the Vernier/LoggerPro software using the start menu. Then File Open Experiment Chemistry with Computers 25 Titration dip acid. Make sure the vertical axis of the graph is ph scaled from 0 to 14 ph units and the horizontal axis reads 0 to 50mL. Change the axes as necessary. Calibrating the ph electrode: 3. Obtain two buffer solutions, one each of buffer ph 4 and buffer ph 7. Do not contaminate or dilute these solutions! They can be reused by other groups. Place the ph probe into the ph 4 buffer solution. Go to the menu and under the Experiment open Calibrate. Click Calibrate now. The electrode will be reading a voltage when this value has stabilized, type in the ph of your buffer (4.0) into the Enter Value box under Reading 1 and then click Keep. Rinse your electrode and place it into the ph 7 buffer solution. When the voltage has stabilized again, enter that ph value (7.0) in the box under Reading 2 and click keep. Click done to return to the graph and data table screen. Rinse the electrode and place the probe back into the ph 4 buffer to make sure it is stable. If the electrode is properly calibrated, the ph of the solution should read 4.00 ± 0.05 units. If your ph value is significantly different (±0.05 ph units) than the buffer you are checking, or if the value drifts slowly to a higher or lower number, contact your lab instructor. Preparing solutions and setting up the titration apparatus: 4. Obtain a MAXIMUM of 100 ml of NaOH in a clean and dry beaker. You will use this NaOH for both experiments. Record the precise concentration of the NaOH solution in the Data and Calculations table. 5. Obtain a 50-mL buret and rinse the buret with about 5 ml of the ~0.1 N NaOH solution. Roll the NaOH in the buret to coat and rinse all sides, and drain the NaOH through the tip into a waste beaker. Use a buret clamp to attach the buret to the ring stand as shown in Figure 4. Fill the buret a little above the 0.00-mL level of the buret. Drain a small amount of NaOH solution so it fills the buret tip and leaves the NaOH at the 0.00-mL level of the buret. You do not need to start exactly at 0.00-mL- you can record the initial volume and subtract it from the final, to get your total volume. Exp #8 Potentiometric Titrations Rev W10 NF Winter 2010 Page 6 of 12

7 Use a buret clamp, not a regular clamp as shown in the figure! Figure 4 6. Place about 100 ml of distilled water into a 250 ml beaker. From a buret already set up for you at the reagent bench, measure to the nearest ±0.01 ml, 20 ml of an acid, HCl, of unknown concentration directly into the beaker. 7. Place the beaker with your acid on a magnetic stirrer and add a stirring bar. Titration 8. Use a three prong utility clamp to suspend a ph electrode on a ring stand as shown in Figure 4. Position the ph electrode in the HCl (or H 3 ) solution and adjust its position toward the outside of the beaker so that it is not struck by the stirring bar. 9. You are now ready to begin the titration. This process goes faster if one person manipulates and reads the buret while another person operates the computer and enters buret readings. Before adding any NaOH titrant, click on the Collect button and monitor ph for 5-10 seconds. After the ph has stabilized, click on the Keep button. Enter the current buret level, You have now stored the first data pair. Add enough NaOH to raise the ph by about 0.20 units. After the NaOH has been added and the ph has stabilized, click on the Keep button. Enter the new buret reading, to the nearest 0.01 ml. Be sure that the ph has stabilized! There is a delay between the addition of NaOH and a stable ph reading. Continue adding NaOH solution in increments that raise the ph about 0.20 units and enter the buret reading after each addition. By watching your graph, it will be easy to see when your ph starts jumping significantly for a small amount of base added. Adjust the amount of NaOH added to keep the ph changes at 0.20 units. Slow down your titration and collect data. Eventually you will collect every one or two drops to get good data for the equivalence point regions. Once again, be sure that the ph has stabilized! When you have reached a flat region past the equivalence point for HCl or when the ph is greater than 11 for H 3 you may Stop the titration. 10. Change the title of your graph appropriately. Click on the graph and from the File menu choose Print window and proceed to print the graph. Click on the data table window and again choose print window and print the data table. You may want to include your name in the title. 11. Double check the electrode with a buffer solution and make sure it is still calibrated. Repeat the titration with the H 3 (using about 20 ml of acid, read and recorded to the nearest 0.01 ml). **** Dispose of the beaker and buret contents and any other solutions in the collection bottles. Exp #8 Potentiometric Titrations Rev W10 NF Winter 2010 Page 7 of 12

8 Processing the Data 1. Use your graph to determine the volume of NaOH titrant used at the equivalence point of your acid. For HCl you will have one equivalence point and therefore one volume of NaOH and for H 3 you will see two equivalence points, so you will have two volumes. To do so, examine the data table to find the largest increase in ph values during the drop-wise additions of NaOH. Make sure that it coincides with the steepest slope on your graph. The equivalence point is the midpoint of the jump in the titration curve. You may use an actual data point, if you have one near that midpoint, or you may average the two points that straddle the midpoint. To do so, find the NaOH volume just before this jump. Then find the NaOH volume from the data after this ph jump. Underline both of these data pairs on the printed data table. Record these volumes in the data table. 2. Calculate the molarity of your acids using the equivalence points from your graph or data. With HCl there will be only 1 equivalence point; with H 3 there will be two so you can calculate 2 values for M. Calculate the molarity of the phosphoric acid at the second equivalence point by taking the volume at the first equivalence point and subtracting it from the volume of the second use this subtracted volume to calculate the molarity at the second equivalence point. 3. On your printed graphs, clearly label/specify the position of the equivalence point volumes you determined in Step 2, using dotted reference lines like those in Figures 2 and 3. Indicate with an x the NaOH volume of each equivalence point on the horizontal axis of the graphs. 4. On your printed graphs, clearly label the two half-equivalence points (see Figure 3 as a reference). Reading your graphs, determine pka 1 and pka 2 and report these values in the data table. (report your values to 2 sf) 5. Record your concentration data in the spreadsheet on the indicated computer and compare your results to the class average. Either the lab instructor or your lecture instructor will provide you with the class averages when they become available. Exp #8 Potentiometric Titrations Rev W10 NF Winter 2010 Page 8 of 12

9 Report Sheet Lecturer Potentiometric Titrations Name Stamp here Partner Data and Calculations -Attach all data tables and labeled graphs (see previous page) This table must be completed in lab to earn a final stamp. HCl Titration. H 3 Titration Initial volumes of Acid Concentration of NaOH Volume of NaOH at Eq.Pt. 1 Volume of NaOH at Eq.Pt. 2 Molarity of acid. Show calc. below. Molarity of acid. At eq. pt. 2 N/A for HCl N/A for HCl E.P. 1 E.P. 2 *For Vol. 2, you will subtract the Vol. at Eq. pt 1 from that at Eq. pt. 2 Volume 2* pk a1 = pk a2 = Your Average M for H 3 = Calculations for M of HCl- show formulas and all units. For instructor use only: [HCl] = Calculations for M of H 3 - show formulas and all units. [H 3 ] = initials: Class average for M of HCl Class average for M of H 3 Exp #8 Potentiometric Titrations Rev W10 NF Winter 2010 Page 9 of 12

10 Questions: (may be completed in lab or at home) 1. Calculate the % difference between your value for the concentration of the HCl and that of the class average. 2. Do the same for the H Based on your data, what is the normality of the HCl solution? 4. Taking into account the fact that H 3 is triprotic, and that you ve only examined the first two equivalence points, use your data to estimate the volume of base that would be required to reach the third equivalence point. Using that estimated value, calculate the normality of the H 3. Exp #8 Potentiometric Titrations Rev W10 NF Winter 2010 Page 10 of 12

11 5. Using the K a values provided in the lab, calculate pk a1 and pk a2. (report your values to two sf) 6. Calculate the % difference between the calculated pk a values (consider these to be the ideal values) and the values you read off your graph. (pay attention to sf in this calculation!) Exp #8 Potentiometric Titrations Rev W10 NF Winter 2010 Page 11 of 12

12 Prelab Assignment Stamp here Name 1. Write the ionic and net ionic equation for the reaction of HNO 3 (aq) with NaOH(aq). 2. The following graph shows the equivalence points for a diprotic acid. Label the axis and indicate on the graph the equivalence points and the ½ equivalence points 3. H 2 SO 3 (aq) + 2 NaOH (aq) 2 H 2 O (l) + Na 2 SO 3 (aq) a. Is sulfurous acid a strong or weak acid? b. What is the definition of a weak acid? c. Write the ionic and net ionic equation for the reaction. d. If ml of N NaOH solution is used to titrate ml of H 2 SO 3 (aq) to the first equivalence point, what is the molarity of the acid? (hints: review your acids and bases lab! And at the first eq. pt. how many H + ions have reacted? ) e. What total volume of NaOH solution would be needed to get to the second equivalence point? ml f. Use your answer to part d to compute the normality of the H 2 SO 3. Exp #8 Potentiometric Titrations Rev W10 NF Winter 2010 Page 12 of 12

Evaluation copy. Titration of a Diprotic Acid: Identifying an Unknown. Computer

Evaluation copy. Titration of a Diprotic Acid: Identifying an Unknown. Computer Titration of a Diprotic Acid: Identifying an Unknown Computer 25 A diprotic acid is an acid that yields two H + ions per acid molecule. Examples of diprotic acids are sulfuric acid, H 2 SO 4, and carbonic

More information

POTENTIOMETRIC TITRATION OF A WEAK ACID

POTENTIOMETRIC TITRATION OF A WEAK ACID POTENTIOMETRIC TITRATION OF A WEAK ACID A Weak Acid/Strong Base Titration For this experiment: 1. Complete the Prelab and obtain a stamp before you begin the experiment. 2. Write your lab notebook prelab

More information

Experiment 6 Titration II Acid Dissociation Constant

Experiment 6 Titration II Acid Dissociation Constant 6-1 Experiment 6 Titration II Acid Dissociation Constant Introduction: An acid/base titration can be monitored with an indicator or with a ph meter. In either case, the goal is to determine the equivalence

More information

Chem 1B Saddleback College Dr. White 1. Experiment 8 Titration Curve for a Monoprotic Acid

Chem 1B Saddleback College Dr. White 1. Experiment 8 Titration Curve for a Monoprotic Acid Chem 1B Saddleback College Dr. White 1 Experiment 8 Titration Curve for a Monoprotic Acid Objectives To learn the difference between titration curves involving a strong acid with a strong base and a weak

More information

DETERMINATION OF PHOSPHORIC ACID CONTENT IN SOFT DRINKS

DETERMINATION OF PHOSPHORIC ACID CONTENT IN SOFT DRINKS DETERMINATION OF PHOSPHORIC ACID CONTENT IN SOFT DRINKS LAB PH 8 From Chemistry with Calculators, Vernier Software & Technology, 2000 INTRODUCTION Phosphoric acid is one of several weak acids that present

More information

ph: Measurement and Uses

ph: Measurement and Uses ph: Measurement and Uses One of the most important properties of aqueous solutions is the concentration of hydrogen ion. The concentration of H + (or H 3 O + ) affects the solubility of inorganic and organic

More information

Acid Base Titrations

Acid Base Titrations Acid Base Titrations Introduction A common question chemists have to answer is how much of something is present in a sample or a product. If the product contains an acid or base, this question is usually

More information

To determine the equivalence points of two titrations from plots of ph versus ml of titrant added.

To determine the equivalence points of two titrations from plots of ph versus ml of titrant added. Titration Curves PURPOSE To determine the equivalence points of two titrations from plots of ph versus ml of titrant added. GOALS 1 To gain experience performing acid-base titrations with a ph meter. 2

More information

ph units constitute a scale which allows scientists to determine the acid or base content of a substance or solution. The ph 0

ph units constitute a scale which allows scientists to determine the acid or base content of a substance or solution. The ph 0 ACID-BASE TITRATION LAB PH 2.PALM INTRODUCTION Acids and bases represent a major class of chemical substances. We encounter them every day as we eat, clean our homes and ourselves, and perform many other

More information

Experiment 17: Potentiometric Titration

Experiment 17: Potentiometric Titration 1 Experiment 17: Potentiometric Titration Objective: In this experiment, you will use a ph meter to follow the course of acid-base titrations. From the resulting titration curves, you will determine the

More information

Acid Dissociation Constants and the Titration of a Weak Acid

Acid Dissociation Constants and the Titration of a Weak Acid Acid Dissociation Constants and the Titration of a Weak Acid One of the most important applications of equilibria is the chemistry of acids and bases. The Brønsted-Lowry acid-base theory defines an acid

More information

15. Acid-Base Titration. Discover the concentration of an unknown acid solution using acid-base titration.

15. Acid-Base Titration. Discover the concentration of an unknown acid solution using acid-base titration. S HIFT INTO NEUTRAL 15. Acid-Base Titration Shift into Neutral Student Instruction Sheet Challenge Discover the concentration of an unknown acid solution using acid-base titration. Equipment and Materials

More information

TITRATION OF AN ACID; USING A ph METER. The ph meter is an instrument that measures the ph of a solution and affords a

TITRATION OF AN ACID; USING A ph METER. The ph meter is an instrument that measures the ph of a solution and affords a 62 Experiment #5. Titration of an Acid; Using a ph Meter TITRATION OF AN ACID; USING A ph METER Introduction The ph meter is an instrument that measures the ph of a solution and affords a direct method

More information

18 Conductometric Titration

18 Conductometric Titration Lab Activity 18 CONDUCTOMETRIC TITRATION LAB ACTIVITY 18 Conductometric Titration Background Titration is the a method of determining the concentration of an unknown solution (the analyte) by reacting

More information

GA/7 Potentiometric Titration

GA/7 Potentiometric Titration Rev. 7/99 7-1 INTRODUCTION GA/7 Potentiometric Titration The potentiometric titration is a useful means of characterizing an acid. The ph of a solution is measured as a function of the amount of titrant

More information

Experiment 4 (Future - Lab needs an unknown)

Experiment 4 (Future - Lab needs an unknown) Experiment 4 (Future - Lab needs an unknown) USING A ph TITRATION TO DETERMINE THE ACID CONTENT OF SOFT DRINKS 2 lab periods Reading: Chapter 9, 185-197; Chapter 10, pg 212-218; Chapter 14 pg 317-323,

More information

Determining the Identity of an Unknown Weak Acid

Determining the Identity of an Unknown Weak Acid Purpose The purpose of this experiment is to observe and measure a weak acid neutralization and determine the identity of an unknown acid by titration. Introduction The purpose of this exercise is to identify

More information

Acid-Base Titrations Using ph Measurements

Acid-Base Titrations Using ph Measurements Acid-Base Titrations Using ph Measurements Introduction According to the Brønsted Lowry definition, an acid is a substance that donates a hydrogen ion and a base is a substance which will accept a hydrogen

More information

To see how this data can be used, follow the titration of hydrofluoric acid against sodium hydroxide below. HF (aq) + NaOH (aq) H2O (l) + NaF (aq)

To see how this data can be used, follow the titration of hydrofluoric acid against sodium hydroxide below. HF (aq) + NaOH (aq) H2O (l) + NaF (aq) Weak Acid Titration v120413 You are encouraged to carefully read the following sections in Tro (2 nd ed.) to prepare for this experiment: Sec 4.8, pp 158-159 (Acid/Base Titrations), Sec 16.4, pp 729-43

More information

Acid Base Titration: ph Titration Curve

Acid Base Titration: ph Titration Curve Acid Base Titration: ph Titration Curve OVERVIEW In this experiment, you will perform a ph-monitored titration of acetic acid and of an unknown acid. From the ph titration of the acetic acid, you will

More information

TITRATION CURVES, INDICATORS, AND ACID DISSOCIATION CONSTANTS

TITRATION CURVES, INDICATORS, AND ACID DISSOCIATION CONSTANTS TITRATION CURVES, INDICATORS, AND ACID DISSOCIATION CONSTANTS Adapted from "Chemistry with Computers" Vernier Software, Portland OR, 1997 INTRODUCTION Titration is the volumetric measurement of a solution

More information

Volumetric Analysis. Lecture 5 Experiment 9 in Beran page 109 Prelab = Page 115

Volumetric Analysis. Lecture 5 Experiment 9 in Beran page 109 Prelab = Page 115 Volumetric Analysis Lecture 5 Experiment 9 in Beran page 109 Prelab = Page 115 Experimental Aims To prepare and standardize (determine concentration) a NaOH solution Using your standardized NaOH calculate

More information

Chemistry 119: Experiment 7. Potentiometric Titration of Ascorbic Acid in Vitamin C Tablets

Chemistry 119: Experiment 7. Potentiometric Titration of Ascorbic Acid in Vitamin C Tablets Chemistry 119: Experiment 7 Potentiometric Titration of Ascorbic Acid in Vitamin C Tablets Vitamin C is another name for ascorbic acid (C 6 H 8 O 6, see below ), a weak acid that can be determined by titration

More information

Electrical Conductivity of Aqueous Solutions

Electrical Conductivity of Aqueous Solutions Electrical Conductivity of Aqueous Solutions PRE-LAB ASSIGNMENT: Reading: Chapter 4.-4.3 in Brown, LeMay, Bursten & Murphy.. Using Table in this handout, determine which solution has a higher conductivity,.

More information

1. To perform a potentiometric titration of a sample of Liquid Drano with hydrochloric acid.

1. To perform a potentiometric titration of a sample of Liquid Drano with hydrochloric acid. INTRODUCTION ANALYSIS OF DRAIN CLEANER (Revised: 1-25-93) Many common household cleaners contain acids or bases. Acidic cleaners, such as toilet bowl cleaners, often contain hydrochloric acid or sodium

More information

The introduction of your report should be written on the on the topic of the role of indicators on acid base titrations.

The introduction of your report should be written on the on the topic of the role of indicators on acid base titrations. Experiment # 13A TITRATIONS INTRODUCTION: This experiment will be written as a formal report and has several parts: Experiment 13 A: Basic methods (accuracy and precision) (a) To standardize a base (~

More information

EXPERIMENT INTRODUCTION TO INDICATORS AND ACID-BASE TITRATIONS

EXPERIMENT INTRODUCTION TO INDICATORS AND ACID-BASE TITRATIONS EXPERIMENT INTRODUCTION TO INDICATORS AND ACID-BASE TITRATIONS By Dale A. Hammond, PhD, Brigham Young University Hawaii LEARNING OBJECTIVES The objectives of this experiment are... an introduction to ph

More information

Acid-Base Titrations. Setup for a Typical Titration. Titration 1

Acid-Base Titrations. Setup for a Typical Titration. Titration 1 Titration 1 Acid-Base Titrations Molarities of acidic and basic solutions can be used to convert back and forth between moles of solutes and volumes of their solutions, but how are the molarities of these

More information

AP FREE RESPONSE QUESTIONS ACIDS/BASES

AP FREE RESPONSE QUESTIONS ACIDS/BASES AP FREE RESPONSE QUESTIONS ACIDS/BASES 199 D A chemical reaction occurs when 100. milliliters of 0.200molar HCl is added dropwise to 100. milliliters of 0.100molar Na 3 P0 solution. (a) Write the two net

More information

Introduction. Depolymerization of Poly(lactic acid) Cups to Lactic Acid. Experiment

Introduction. Depolymerization of Poly(lactic acid) Cups to Lactic Acid. Experiment Experiment Depolymerization of Poly(lactic acid) Cups to Lactic Acid 6 Introduction Poly(lactic acid), or PLA, is a biobased polymer that is a promising alternative to fossil-fuel based plastics. PLA is

More information

This value, called the ionic product of water, Kw, is related to the equilibrium constant of water

This value, called the ionic product of water, Kw, is related to the equilibrium constant of water HYDROGEN ION CONCENTRATION - ph VALUES AND BUFFER SOLUTIONS 1. INTRODUCTION Water has a small but definite tendency to ionise. H 2 0 H + + OH - If there is nothing but water (pure water) then the concentration

More information

Properties of Acids and Bases

Properties of Acids and Bases Lab 22 Properties of Acids and Bases TN Standard 4.2: The student will investigate the characteristics of acids and bases. Have you ever brushed your teeth and then drank a glass of orange juice? What

More information

9. Analysis of an Acid-Base Titration Curve: The Gran Plot

9. Analysis of an Acid-Base Titration Curve: The Gran Plot 9. Analysis of an Acid-Base Titration Curve: The Gran Plot In this experiment, you will titrate a sample of pure potassium hydrogen phthalate (Table 10-4) with standard NaOH. A Gran plot will be used to

More information

CHM1 Review for Exam 12

CHM1 Review for Exam 12 Topics Solutions 1. Arrhenius Acids and bases a. An acid increases the H + concentration in b. A base increases the OH - concentration in 2. Strong acids and bases completely dissociate 3. Weak acids and

More information

Experiment 8 - Double Displacement Reactions

Experiment 8 - Double Displacement Reactions Experiment 8 - Double Displacement Reactions A double displacement reaction involves two ionic compounds that are dissolved in water. In a double displacement reaction, it appears as though the ions are

More information

Determination of the Amount of Acid Neutralized by an Antacid Tablet Using Back Titration

Determination of the Amount of Acid Neutralized by an Antacid Tablet Using Back Titration Determination of the Amount of Acid Neutralized by an Antacid Tablet Using Back Titration GOAL AND OVERVIEW Antacids are bases that react stoichiometrically with acid. The number of moles of acid that

More information

Juice Titration. Background. Acid/Base Titration

Juice Titration. Background. Acid/Base Titration Juice Titration Background Acids in Juice Juice contains both citric and ascorbic acids. Citric acid is used as a natural preservative and provides a sour taste. Ascorbic acid is a water-soluble vitamin

More information

Ascorbic Acid Titration of Vitamin C Tablets This lab will be completed individually! Make sure you come prepared!

Ascorbic Acid Titration of Vitamin C Tablets This lab will be completed individually! Make sure you come prepared! Ascorbic Acid Titration of Vitamin C Tablets This lab will be completed individually! Make sure you come prepared! Introduction Vitamin C (also known as ascorbic acid, HC6H7O6) is a necessary ingredient

More information

ACID-BASE TITRATIONS: DETERMINATION OF CARBONATE BY TITRATION WITH HYDROCHLORIC ACID BACKGROUND

ACID-BASE TITRATIONS: DETERMINATION OF CARBONATE BY TITRATION WITH HYDROCHLORIC ACID BACKGROUND #3. Acid - Base Titrations 27 EXPERIMENT 3. ACID-BASE TITRATIONS: DETERMINATION OF CARBONATE BY TITRATION WITH HYDROCHLORIC ACID BACKGROUND Carbonate Equilibria In this experiment a solution of hydrochloric

More information

The Determination of Acid Content in Vinegar

The Determination of Acid Content in Vinegar The Determination of Acid Content in Vinegar Reading assignment: Chang, Chemistry 10 th edition, pages 153-156. Goals We will use a titration to determine the concentration of acetic acid in a sample of

More information

Chapter 10 Acid-Base titrations Problems 1, 2, 5, 7, 13, 16, 18, 21, 25

Chapter 10 Acid-Base titrations Problems 1, 2, 5, 7, 13, 16, 18, 21, 25 Chapter 10 AcidBase titrations Problems 1, 2, 5, 7, 13, 16, 18, 21, 25 Up to now we have focused on calculations of ph or concentration at a few distinct points. In this chapter we will talk about titration

More information

Neutralizing an Acid and a Base

Neutralizing an Acid and a Base Balancing Act Teacher Information Objectives In this activity, students neutralize a base with an acid. Students determine the point of neutralization of an acid mixed with a base while they: Recognize

More information

MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Chemistry 5.310 Laboratory Chemistry THE POTENTIOMETRIC TITRATION OF AN ACID MIXTURE 1

MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Chemistry 5.310 Laboratory Chemistry THE POTENTIOMETRIC TITRATION OF AN ACID MIXTURE 1 MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Chemistry 5.310 Laboratory Chemistry EXPERIMENT #5 THE POTENTIOMETRIC TITRATION OF AN ACID MIXTURE 1 I. PURPOSE OF THE EXPERIMENT In this experiment

More information

Lab #10 How much Acetic Acid (%) is in Vinegar?

Lab #10 How much Acetic Acid (%) is in Vinegar? Lab #10 How much Acetic Acid (%) is in Vinegar? SAMPLE CALCULATIONS NEED TO BE DONE BEFORE LAB MEETS!!!! Purpose: You will determine the amount of acetic acid in white vinegar (sold in grocery stores)

More information

Titrations. Acid-Base Indicators and Titration Curves. Shapes of Titration Curves. A titration curve is a graphical history of a titration

Titrations. Acid-Base Indicators and Titration Curves. Shapes of Titration Curves. A titration curve is a graphical history of a titration Acid-Base Indicators and Titration Curves Titrations In a titration a solution of accurately known concentration is added gradually added to another solution of unknown concentration until the chemical

More information

STANDARDIZATION OF A SODIUM HYDROXIDE SOLUTION EXPERIMENT 14

STANDARDIZATION OF A SODIUM HYDROXIDE SOLUTION EXPERIMENT 14 STANDARDIZATION OF A SODIUM HYDROXIDE SOLUTION EXPERIMENT 14 OBJECTIVE The objective of this experiment will be the standardization of sodium hydroxide using potassium hydrogen phthalate by the titration

More information

ph and Acidity in Wine and Fruit Juice

ph and Acidity in Wine and Fruit Juice ph and Acidity in Wine and Fruit Juice DOC316.52.93089 Endpoint potentiometric titration Scope and application: Wine and fruit juice 1. Introduction This working procedure refers to the titration of total

More information

Experiment 18: ph Measurements of Common Substances. Experiment 17: Reactions of Acids with Common Substances

Experiment 18: ph Measurements of Common Substances. Experiment 17: Reactions of Acids with Common Substances Experiment 18: ph Measurements of Common Substances and Experiment 17: Reactions of Acids with Common Substances What is this lab about? You mean what ARE THESE labs about? Ok, so what are THESE labs about?

More information

Q.1 Classify the following according to Lewis theory and Brønsted-Lowry theory.

Q.1 Classify the following according to Lewis theory and Brønsted-Lowry theory. Acid-base 2816 1 Acid-base theories ACIDS & BASES - IONIC EQUILIBRIA LEWIS acid electron pair acceptor H +, AlCl 3 base electron pair donor NH 3, H 2 O, C 2 H 5 OH, OH e.g. H 3 N: -> BF 3 > H 3 N + BF

More information

ph and Acidity in Tomato Sauce

ph and Acidity in Tomato Sauce ph and Acidity in Tomato Sauce DOC316.52.93100 Endpoint potentiometric titration Scope and application: Tomato sauce 1. Introduction This working procedure refers to the determination of titratable acidity

More information

Experiment 7: Titration of an Antacid

Experiment 7: Titration of an Antacid 1 Experiment 7: Titration of an Antacid Objective: In this experiment, you will standardize a solution of base using the analytical technique known as titration. Using this standardized solution, you will

More information

Q.1 Classify the following according to Lewis theory and Brønsted-Lowry theory.

Q.1 Classify the following according to Lewis theory and Brønsted-Lowry theory. Acid-base A4 1 Acid-base theories ACIDS & BASES - IONIC EQUILIBRIA 1. LEWIS acid electron pair acceptor H, AlCl 3 base electron pair donor NH 3, H 2 O, C 2 H 5 OH, OH e.g. H 3 N: -> BF 3 > H 3 N BF 3 see

More information

EXPERIMENT 7. Identifying a Substance by Acid-Base Titration

EXPERIMENT 7. Identifying a Substance by Acid-Base Titration EXPERIMENT 7 Identifying a Substance by Acid-Base Titration SAFETY WARNING In this experiment you will be working with NaOH pellets and using 0.25 M NaOH as a titrant. Sodium hydroxide is extremely basic,

More information

A Potentiometric Analysis of Fluoride Ion in Toothpaste

A Potentiometric Analysis of Fluoride Ion in Toothpaste CHEM 311L Quantitative Analysis Laboratory Revision 2.0 A Potentiometric Analysis of Fluoride Ion in Toothpaste In this laboratory exercise, we will analyze a toothpaste sample for its Fluoride Ion (F

More information

(1) Hydrochloric acid reacts with sodium hypochlorite to form hypochlorous acid: NaOCl(aq) + HCl(aq) HOCl(aq) + NaCl(aq) hypochlorous acid

(1) Hydrochloric acid reacts with sodium hypochlorite to form hypochlorous acid: NaOCl(aq) + HCl(aq) HOCl(aq) + NaCl(aq) hypochlorous acid The Determination of Hypochlorite in Bleach Reading assignment: Chang, Chemistry 10 th edition, pages 156-159. We will study an example of a redox titration in order to determine the concentration of sodium

More information

Direct ISE Method Method 8359 10 to 1000 mg/l Na + Sodium ISE

Direct ISE Method Method 8359 10 to 1000 mg/l Na + Sodium ISE Sodium DOC316.53.01240 Direct ISE Method Method 8359 10 to 1000 mg/l Na + Sodium ISE Scope and application: For drinking water and process water. Test preparation Instrument-specific information This procedure

More information

Titration curves. Strong Acid-Strong Base Titrations

Titration curves. Strong Acid-Strong Base Titrations Titration curves A titration is a procedure for carrying out a chemical reaction between two solutions by the controlled addition from a buret of one solution (the titrant) to the other, allowing measurements

More information

The Determination of an Equilibrium Constant

The Determination of an Equilibrium Constant The Determination of an Equilibrium Constant Computer 10 Chemical reactions occur to reach a state of equilibrium. The equilibrium state can be characterized by quantitatively defining its equilibrium

More information

EXPERIMENT 12 A SOLUBILITY PRODUCT CONSTANT

EXPERIMENT 12 A SOLUBILITY PRODUCT CONSTANT PURPOSE: 1. To determine experimentally the molar solubility of potassium acid tartrate in water and in a solution of potassium nitrate. 2. To examine the effect of a common ion on the solubility of slightly

More information

EXPERIMENT 2 THE HYDROLYSIS OF t-butyl CHLORIDE. PURPOSE: To verify a proposed mechanism for the hydrolysis of t-butyl Chloride.

EXPERIMENT 2 THE HYDROLYSIS OF t-butyl CHLORIDE. PURPOSE: To verify a proposed mechanism for the hydrolysis of t-butyl Chloride. PURPOSE: To verify a proposed mechanism for the hydrolysis of t-butyl Chloride. PRINCIPLES: Once the Rate Law for a reaction has been experimentally established the next step is its explanation in terms

More information

ACID-BASE TITRATIONS

ACID-BASE TITRATIONS ACID-BASE TITRATIONS 1 In this exercise you will use Excel to construct titration curves for a titration between a strong acid and strong base and between a weak acid and strong base. To set up a spreadsheet

More information

ph Measurements of Common Substances

ph Measurements of Common Substances Chem 100 Section Experiment 10 Name Partner s Name Introduction ph Measurements of Common Substances The concentration of an acid or base is frequently expressed as ph. Historically, ph stands for the

More information

CHM 130LL: ph, Buffers, and Indicators

CHM 130LL: ph, Buffers, and Indicators CHM 130LL: ph, Buffers, and Indicators Many substances can be classified as acidic or basic. Acidic substances contain hydrogen ions, H +, while basic substances contain hydroxide ions, OH. The relative

More information

EXPERIMENT 10: TITRATION AND STANDARDIZATION

EXPERIMENT 10: TITRATION AND STANDARDIZATION EXPERIMENT 10: TITRATION AND STANDARDIZATION PURPOSE To determine the molarity of a NaOH solution by titrating it with a standard HCl solution. To determine the molarity of acetic acid in vinegar using

More information

Auto-ionization of Water

Auto-ionization of Water 2H 2 O H 3 O + + OH Hydronium ion hydroxide ion Q: But how often does this happen? This is the fundamental concept of all acid-base chemistry In pure water, how much of it is water and how much is ions?

More information

Chapter 14 - Acids and Bases

Chapter 14 - Acids and Bases Chapter 14 - Acids and Bases 14.1 The Nature of Acids and Bases A. Arrhenius Model 1. Acids produce hydrogen ions in aqueous solutions 2. Bases produce hydroxide ions in aqueous solutions B. Bronsted-Lowry

More information

Lab 25. Acid-Base Titration and Neutralization Reactions: What Is the Concentration of Acetic Acid in Each Sample of Vinegar?

Lab 25. Acid-Base Titration and Neutralization Reactions: What Is the Concentration of Acetic Acid in Each Sample of Vinegar? Lab 25. Acid-Base Titration and Neutralization Reactions: What Is the Concentration of Acetic Acid in Each Sample of Vinegar? Introduction Vinegar is basically a solution of acetic acid (CH3COOH). It is

More information

Electrochemistry Revised 04/29/15

Electrochemistry Revised 04/29/15 INTRODUCTION TO ELECTROCHEMISTRY: CURRENT, VOLTAGE, BATTERIES, & THE NERNST EQUATION Experiment partially adapted from J. Chem. Educ., 2008, 85 (8), p 1116 Introduction Electrochemical cell In this experiment,

More information

HOW TO MAKE STANDARD SOLUTIONS FOR CHEMISTRY

HOW TO MAKE STANDARD SOLUTIONS FOR CHEMISTRY HOW TO MAKE STANDARD SOLUTIONS FOR CHEMISTRY Phillip Bigelow Chemists make two common types of "standard solutions": Molar solutions Normal solutions Both of these solutions are concentrations (or strengths

More information

Calcium Analysis by EDTA Titration

Calcium Analysis by EDTA Titration Calcium Analysis by EDTA Titration ne of the factors that establish the quality of a water supply is its degree of hardness. The hardness of water is defined in terms of its content of calcium and magnesium

More information

Topic 18 Acids and Bases. 18.1 Exercises

Topic 18 Acids and Bases. 18.1 Exercises Topic 18 Acids and Bases 18.1 Exercises 1. Define: (a) ph The negative log of the hydrogen ion concentration in a solution. i.e. ph = log[h 3 O + ] (b) poh The negative log of hydroxide ion concentration

More information

Neutralization Reactions. Evaluation copy

Neutralization Reactions. Evaluation copy Neutralization Reactions Computer 6 If an acid is added to a base, a chemical reaction called neutralization occurs. An example is the reaction between nitric acid, HNO 3, and the base potassium hydroxide,

More information

EXPERIMENT 4 Acid Strength

EXPERIMENT 4 Acid Strength EXPERIMENT 4 Acid Strength Introduction Many common substances are either acids or bases. Some acids, like stomach acid are necessary for our health, while others, like sulfuric acid are dangerous and

More information

6 H2O + 6 CO 2 (g) + energy

6 H2O + 6 CO 2 (g) + energy AEROBIC RESPIRATION LAB DO 2.CALC From Biology with Calculators, Vernier Software & Technology, 2000. INTRODUCTION Aerobic cellular respiration is the process of converting the chemical energy of organic

More information

3 The Preparation of Buffers at Desired ph

3 The Preparation of Buffers at Desired ph 3 The Preparation of Buffers at Desired ph Objectives: To become familiar with operating a ph meter, and to learn how to use the Henderson-Hasselbalch equation to make buffer solutions at a desired ph

More information

Acid/Base Definition. Acid/Base Reactions. Major vs. Minor Species. Terms/Items you Need to Know. you need to memorize these!!

Acid/Base Definition. Acid/Base Reactions. Major vs. Minor Species. Terms/Items you Need to Know. you need to memorize these!! Acid/Base Reactions some covalent compounds have weakly bound H atoms and can lose them to water (acids) some compounds produce OH in water solutions when they dissolve (bases) acid/base reaction are very

More information

COMMON LABORATORY APPARATUS

COMMON LABORATORY APPARATUS COMMON LABORATORY APPARATUS Beakers are useful as a reaction container or to hold liquid or solid samples. They are also used to catch liquids from titrations and filtrates from filtering operations. Bunsen

More information

Determination of Citric Acid in Powdered Drink Mixes

Determination of Citric Acid in Powdered Drink Mixes Determination of Citric Acid in Powdered Drink Mixes Citric acid and its salts (sodium citrate and potassium citrate) are found in many foods, drinks, pharmaceuticals, shampoos, and cosmetics. The tartness

More information

Potentiometry: The ph Electrode and Potentiometric Titrations

Potentiometry: The ph Electrode and Potentiometric Titrations Potentiometry: The ph Electrode and Potentiometric Titrations In this experiment you will investigate the Nernstian response of a ph electrode, perform potentiometric titrations, investigate the acid-base

More information

Determination of a Chemical Formula

Determination of a Chemical Formula 1 Determination of a Chemical Formula Introduction Molar Ratios Elements combine in fixed ratios to form compounds. For example, consider the compound TiCl 4 (titanium chloride). Each molecule of TiCl

More information

Determination of Aspirin using Back Titration

Determination of Aspirin using Back Titration Determination of Aspirin using Back Titration This experiment is designed to illustrate techniques used in a typical indirect or back titration. You will use the NaH you standardized last week to back

More information

Drop Counter Sensor Product Number: ENDRP-AD100

Drop Counter Sensor Product Number: ENDRP-AD100 imagine explore learn Drop Counter Sensor Product Number: ENDRP-AD100 Overview The Drop Counter sensor is an optical sensor that accurately records the number of drops of titrant added during a titration.

More information

Separation by Solvent Extraction

Separation by Solvent Extraction Experiment 3 Separation by Solvent Extraction Objectives To separate a mixture consisting of a carboxylic acid and a neutral compound by using solvent extraction techniques. Introduction Frequently, organic

More information

CHAPTER 16: ACIDS AND BASES

CHAPTER 16: ACIDS AND BASES CHAPTER 16: ACIDS AND BASES Active Learning: 4, 6, 14; End-of-Chapter Problems: 2-25, 27-58, 66-68, 70, 75-77, 83, 90-91, 93-104 Chapter 15 End-of-Chapter Problems: 69-74, 125, 129, 133 16.1 ACIDS AND

More information

Chem101: General Chemistry Lecture 9 Acids and Bases

Chem101: General Chemistry Lecture 9 Acids and Bases : General Chemistry Lecture 9 Acids and Bases I. Introduction A. In chemistry, and particularly biochemistry, water is the most common solvent 1. In studying acids and bases we are going to see that water

More information

TOPIC 11: Acids and Bases

TOPIC 11: Acids and Bases TOPIC 11: Acids and Bases ELECTROLYTES are substances that when dissolves in water conduct electricity. They conduct electricity because they will break apart into Ex. NaCl(s)! Na + (aq) + Cl - (aq), and

More information

Acid Base Titrations in Aqueous Solvents

Acid Base Titrations in Aqueous Solvents Acid Base Titrations in Aqueous Solvents Introduction: All kind of titrations in various samples are performed today in process analysers and laboratories, by far the most of them are acid base titrations.

More information

Additional Lecture: TITRATION BASICS

Additional Lecture: TITRATION BASICS Additional Lecture: TITRATION BASICS 1 Definition and Applications Titration is the incremental addition of a reagent solution (called titrant) to the analyte until the reaction is complete Common applications:

More information

Experiment 6 Coffee-cup Calorimetry

Experiment 6 Coffee-cup Calorimetry 6-1 Experiment 6 Coffee-cup Calorimetry Introduction: Chemical reactions involve the release or consumption of energy, usually in the form of heat. Heat is measured in the energy units, Joules (J), defined

More information

Experiment 2 Kinetics II Concentration-Time Relationships and Activation Energy

Experiment 2 Kinetics II Concentration-Time Relationships and Activation Energy 2-1 Experiment 2 Kinetics II Concentration-Time Relationships and Activation Energy Introduction: The kinetics of a decomposition reaction involving hydroxide ion and crystal violet, an organic dye used

More information

Dissolving of sodium hydroxide generates heat. Take care in handling the dilution container.

Dissolving of sodium hydroxide generates heat. Take care in handling the dilution container. TITRATION: STANDARDIZATION OF A BASE AND ANALYSIS OF STOMACH ANTACID TABLETS 2009, 1996, 1973 by David A. Katz. All rights reserved. Reproduction permitted for education use provided original copyright

More information

We remember that molarity (M) times volume (V) is equal to moles so this relationship is the definition of the equivalence point.

We remember that molarity (M) times volume (V) is equal to moles so this relationship is the definition of the equivalence point. Titrations Titration - a titration is defined as the determination of the amount of an unknown reagent (analyte) through the use of a known amount of another reagent (titrant) in an essentially irreversible

More information

Determining the Quantity of Iron in a Vitamin Tablet. Evaluation copy

Determining the Quantity of Iron in a Vitamin Tablet. Evaluation copy Determining the Quantity of Iron in a Vitamin Tablet Computer 34 As biochemical research becomes more sophisticated, we are learning more about the role of metallic elements in the human body. For example,

More information

Total Water Hardness

Total Water Hardness Test 14 INTRODUCTION When water passes through or over deposits such as limestone, the levels of Ca 2+, Mg 2+, and HCO Ð 3 ions present in the water can greatly increase and Hard-Water Cations cause the

More information

Extraction: Separation of Acidic Substances

Extraction: Separation of Acidic Substances Extraction: Separation of Acidic Substances Chemists frequently find it necessary to separate a mixture of compounds by moving a component from one solution or mixture to another. The process most often

More information

Chem 321 Lecture 13 - Acid-Base Titrations 10/10/13

Chem 321 Lecture 13 - Acid-Base Titrations 10/10/13 Student Learning Objectives Chem 321 Lecture 13 - Acid-Base Titrations 10/10/13 Indicators A common end point for acid-base titrations is the color change associated with an acid-base indicator. An acid-base

More information

Chemistry 112 Laboratory Experiment 6: The Reaction of Aluminum and Zinc with Hydrochloric Acid

Chemistry 112 Laboratory Experiment 6: The Reaction of Aluminum and Zinc with Hydrochloric Acid Chemistry 112 Laboratory Experiment 6: The Reaction of Aluminum and Zinc with Hydrochloric Acid Introduction Many metals react with acids to form hydrogen gas. In this experiment, you will use the reactions

More information

Pre-Lab Notebook Content: Your notebook should include the title, date, purpose, procedure; data tables.

Pre-Lab Notebook Content: Your notebook should include the title, date, purpose, procedure; data tables. Determination of Molar Mass by Freezing Point Depression M. Burkart & M. Kim Experimental Notes: Students work in pairs. Safety: Goggles and closed shoes must be worn. Dispose of all chemical in the plastic

More information

Chemical equilibria Buffer solutions

Chemical equilibria Buffer solutions Chemical equilibria Buffer solutions Definition The buffer solutions have the ability to resist changes in ph when smaller amounts of acid or base is added. Importance They are applied in the chemical

More information

Determining Equivalent Weight by Copper Electrolysis

Determining Equivalent Weight by Copper Electrolysis Purpose The purpose of this experiment is to determine the equivalent mass of copper based on change in the mass of a copper electrode and the volume of hydrogen gas generated during an electrolysis reaction.

More information