# The Determination of an Equilibrium Constant

Size: px
Start display at page:

Transcription

1 The Determination of an Equilibrium Constant Chemical reactions occur to reach a state of equilibrium. The equilibrium state can be characterized by quantitatively defining its equilibrium constant, K eq. See Vernier # 10 BACKGROUND Think of the simple reaction between reactants A & B creating product C: A + B C A snapshot of the reaction, where x & y are the concentration of A (Fe + ) and B (SCN ) and z is the concentration of C (FeSCN + ), the product, and can be represented as: xa + yb <----> zc + (x-z)a + (y-z)b In this experiment the initial concentration of A is held constant, while the concentration of B is changed, as per. At the beginning of the reaction (time, t=0) there is only A & B, because no C has been formed. At equilibrium (time=t eq ), some of the reactants A & B have been consumed to form the product C. The amount of A & B remaining at equilibrium can be determined based upon the mole ratios between A, B, and C. For this simple example, the mole ratio between A:B:C is 1:1:1 thus, for every mole of product formed one mole of A is consumed and one mole of B is consumed. At t=0 at t=t equil # moles of A = A init # moles of A equil = A init - # moles of C equil # moles of B = B init # moles of B equil = B init - # moles of C equil # moles of C = 0 # moles of C equil = C equil which can be measured. The equilibrium constant, K eq = [products] / [reactants], so in this simple model: K eq = [C equil ] / ([A equil ] * [B equil ]) EXPERIMENT In this experiment, you will determine the value of K eq for the reaction between iron (III) ions and thiocyanate ions, SCN. Fe(NO ) (aq) + KSCN (aq) FeSCN + (aq) From simple model: A B C The equilibrium constant, K eq, is defined by the equation shown below. [FeSCN + ] K eq = (equation 1) ( [Fe(NO ) ] equil [KSCN] equil ) To find the value of K eq, it is necessary to determine the molar concentration [mol/l] of each of 1

2 the three species in solution at equilibrium (at constant temperature). You will use a spectrophotometer to help you measure the concentrations. The amount of light absorbed by a colored solution is proportional to its concentration. In part I of this experiment, you will first prepare a series of standard solutions of FeSCN + from solutions of varying concentrations of SCN and constant concentrations of H + and Fe + that are in stoichiometric excess. The excess of H + ions will ensure that Fe + engages in no side reactions (to form FeOH +, for example). The excess of Fe + ions will make the SCN ions the limiting reagent, thus all of the SCN used will form FeSCN + ions. The FeSCN + complex forms slowly, taking at least one minute for the color to develop. It is best to take absorbance readings after a specific amount of time has elapsed, between two and four minutes after preparing the equilibrium mixture. Unless instructed otherwise, take all readings for ABSORBANCE at 10 seconds. Do not wait much longer than four minutes to take readings, however, because the mixture is light sensitive and the FeSCN + ions will slowly decompose. From this data, you will create a calibration curve of Absorbance vs. [FeSCN + ] (the product) and determine the equation for the line y=mx+b. In part II, you will prepare a new series of solutions that have varied concentrations of the Fe + ions and the SCN ions, with a constant concentration of H + ions. Using the calibration curve generated in Part I, you will use the results of this part to calculate the reaction equilibrium constant. DILUTION CALCULATIONS: Based on M 1 V 1 = M V (M= Molarity, V = Volume) M solution = (M Reactant * V Reactant ) / V Solution (equation ) where V solution = V Reactant + V water PROCEDURE Part I - Prepare and Test Standard Solutions 1. ALWAYS wear glasses when working in the chemistry laboratory.. Label five 100 ml beakers 1-. Obtain small volumes of 0.00 M Fe(NO ), M SCN, and distilled water. CAUTION: Fe(NO ) solutions in this experiment are prepared in 1.0 M HNO and should be handled with care. Prepare four Fe solutions according to the dilution chart in DATA TABLE PART I (adding the desired amount of water). Use a 10.0 ml graduated (1/10mL) to transfer each solution to a 0mL graduate cylinder. Mix each dilution thoroughly. DO NOT MIX THE Fe (III) solution with the SCN until you are ready to measure the absorbance with the spectrometer. DO NOT PREMIX THE CHEMICALS TOGETHER AS THEY WILL REACT! b. Calculate the [Fe(NO ) ] and [KSCN]. Because the Fe + ion is 100 times as concentrated, assume that all of the SCN ions react. From the 1:1:1 stoichiometric relationship of the reactants and product mol of FeSCN + = mol of KSCN = (0.00 mol/l) * (# ml KSCN)/1000

3 [FeSCN + ] = (moles FeSCN + )/Volume of solution [FeSCN + ] = (0.00 mol/l) * (# ml KSCN-)/0 ml (equation ) DATA TABLE - PART I DATA TABLE Prepare Prepare Prepare Total Fe(NO ) Trial 0. M Units ml ml ml ml M Calculate (equation ) Measure and Record KSCN 0.00 M H O [FeSCN + ] ABS Connect a Spectrophotometer to the computer with the USB cable.. Start the Logger Pro program on your computer.. Calibrate the Spectrophotometer. Note: always use the same cuvette! a) Prepare a blank by filling an empty cuvette ¾ full with distilled water. Place the blank in the cuvette slot of the Spectrophotometer and calibrate the instrument. 6. You are now ready to collect absorbance data for the standard solutions. Click COLLECT to begin data collection. a) Empty the water from the cuvette. Create the mixture of Fe (III) and SCN and fill the cuvette ¾ full. Wipe the outside with a tissue, place it in the Spectrophotometer, and close the lid. Wait for the absorbance value displayed in the Meter window to stabilize. In Logger Pro, click the Configure Spectrometer button. Click Abs vs. Concentration as the Collection Mode. Select the wavelength of about nm. Click OK. Note: Take readings at 10 seconds unless directed otherwise. Click KEEP, type the concentration of FeSCN + (from your pre-lab calculations) in the edit box, and press the ENTER key. b) Discard the cuvette contents as directed. Repeat the procedure in Part a of this step to measure the absorbance and record the concentration of each solution for Beakers,, and. c) Click STOP when you have finished collecting data to view a graph of absorbance vs. concentration. 7. Click the Linear Fit button. This line should pass near or through the data points and the origin of the graph. Another option is to choose Curve Fit from the Analyze menu, and then select Proportional. The Proportional fit has a y-intercept value equal to 0; therefore, this regression line will always pass through the origin of the graph). Record the equation of the

4 line y=mx+b for future calculations. (RECORD EQUATION OF THE LINE y=mx+b) Part II YOU WILL USE THE CALIBRATION CURVE YOU CREATED IN PART I TO MEASURE THE CONCENTRATIONS BASED UPON MEASURED ABSORBANCES 8. Prepare five test tubes of solutions, according to the chart below. Follow the necessary steps from Part I to test the absorbance values of each mixture. Record the test results in your data table. Note: You are using M Fe(NO ) in this test. 9. Calculate the concentration of Fe(NO ) and KSCN for each test tube using equation. Record the ABS of each solution in DATA TABLE PART II. DATA TABLE - PART II Record ABS DATA ANALYSIS You must determine the NET ABSORBANCE of the solutions in Test Tubes - to test only the color created by the reaction. Subtract the ABS for Test Tube 1 (containing only Fe and water) from the ABS of Test Tubes -. Use the NET ABSORBANCE values, along with the best fit line equation in Part I to calculate the [FeSCN+] at equilibrium for each of the mixtures that you prepared in Part II. Note: for y = mx + b you will solve for x, thus: [FeSCN + ] = (NET ABS b)/m (Equation ) ANALYSIS TABLE 1 DATA TABLE Measure Measure Measure Total (equation ) (equation ) Fe(NO ) KSCN Initial Initial Trial 0.00 M 0.00 M H O [Fe(NO ) ] [KSCN] Units ml ml ml ml M M ANALYSIS Table From Data Table II Calculate Trial [Fe(NO ) ] inital [KSCN] initial ABS NET ABS Units M M 1 n/a [C equil ] (Equation ) [FeSCN + ]

5 Note the last column is the numerator of equation (1) ANALYSIS TABLE To compute the K eq, you must determine the moles of each REACTANT (A equil, B equil ) that remain when the system is at equilibrium. This is done by computing the number of moles of product created, C equil, and subtracting that from the initial number of moles of each reactant (A init, B init ). Note that all reactant and product ions are dissolved in the same volume of solution (10 ml), so the change in the # moles is the same as the change in the concentrations (Mol/L) for each ion. ANALYSIS Table Table II [C equil ] Product [A equil ] Reactant [B equil ] Reactant Trial [Fe(NO ) ] initial [KSCN] initial [FeSCN + ] [Fe(NO ) ] equil [KSCN] equil Units M M M M M 1 Note the last columns are the denominator of equation (1) Compute Keq using the values computed in ANALYSIS TABLE 1 and ANALYSIS TABLE in Equation 1. ANALYSIS TABLE ANALYSIS (Equation 1) Trial Compute K eq 1 n/a Avg Keq: Conclusion: Compose a final paragraph to discuss the results. Include the equation of the line from the calibration curve: y=mx+b with m and b determined from your data. Complete all remaining portions of the standard lab report.

### 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

### Lab #11: Determination of a Chemical Equilibrium Constant

Lab #11: Determination of a Chemical Equilibrium Constant Objectives: 1. Determine the equilibrium constant of the formation of the thiocyanatoiron (III) ions. 2. Understand the application of using a

### 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,

### Determining the Free Chlorine Content of Swimming Pool Water. HOCl H + + OCl. Evaluation copy

Determining the Free Chlorine Content of Swimming Pool Water Computer 33 Physicians in the nineteenth century used chlorine water as a disinfectant. Upon the discovery that certain diseases were transmitted

### Evaluation copy. Case File 9. A Killer Cup of Coffee? GlobalTech manager dies

Case File 9 Killer Cup of Coffee: Using colorimetry to determine concentration of a poison Determine the concentration of cyanide in the solution. A Killer Cup of Coffee? SOUTH PAINTER, Tuesday: It was

### Chemistry 111 Laboratory Experiment 7: Determination of Reaction Stoichiometry and Chemical Equilibrium

Chemistry 111 Laboratory Experiment 7: Determination of Reaction Stoichiometry and Chemical Equilibrium Introduction The word equilibrium suggests balance or stability. The fact that a chemical reaction

### Upon completion of this lab, the student will be able to:

1 Learning Outcomes EXPERIMENT B4: CHEMICAL EQUILIBRIUM Upon completion of this lab, the student will be able to: 1) Analyze the absorbance spectrum of a sample. 2) Calculate the equilibrium constant for

### 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

### To determine the mass of iron in one adult dose of either a ferrous sulfate or. ferrous gluconate iron supplement using a colorimetric technique.

Lab: Colorimetric Analysis of Iron in Iron Supplements Purpose To determine the mass of iron in one adult dose of either a ferrous sulfate or ferrous gluconate iron supplement using a colorimetric technique.

### GlobalTech manager dies

Case File 9 Killer Cup of Coffee: Using colorimetry to determine concentration of a poison Determine the concentration of cyanide in the solution. A Killer Cup of Coffee? GlobalTech manager dies SOUTH

### AP CHEMISTRY 2006 SCORING GUIDELINES (Form B)

AP CHEMISTRY 2006 SCORING GUIDELINES (Form B) Question 5 5. A student carries out an experiment to determine the equilibrium constant for a reaction by colorimetric (spectrophotometric) analysis. The production

### Chemistry 2351: Inorganic Chemistry I Laboratory Manual

Spectroscopic Determination of a Complex Ion's Stoichiometry by Job's Method ABSTRACT This experiment is adapted from Angelici's classic experiment, but uses Fe(H 2 O) 6-n (SCN) n 3-n as the complex ion.

### Experiment 13H THE REACTION OF RED FOOD COLOR WITH BLEACH 1

Experiment 13H FV 1/25/2011(2-run) THE REACTION OF RED FOOD COLOR WITH BLEACH 1 PROBLEM: Determine the rate law for the chemical reaction between FD&C Red Dye #3 and sodium hypochlorite. LEARNING OBJECTIVES:

### Reaction Stoichiometry and the Formation of a Metal Ion Complex

Reaction Stoichiometry and the Formation of a Metal Ion Complex Objectives The objectives of this laboratory are as follows: To use the method of continuous variation to determine the reaction stoichiometry

### Phosphates (ortho- and total)

INTRODUCTION Phosphates (ortho- and total) Phosphorus is an essential nutrient for all aquatic plants and algae. Only a very small amount is needed, however, so an excess of phosphorus can easily occur.

### Reaction of Blue Food Dye with Bleach

Exercise 2 Reaction of Blue Food Dye with Bleach 2 Introduction In the experiment, you will study the rate of the reaction of FD&C Blue #1 (Blue #1 is denoted by E number E133 in food stuff) with sodium

### Solubility Product Constants

Solubility Product Constants PURPOSE To measure the solubility product constant (K sp ) of copper (II) iodate, Cu(IO 3 ) 2. GOALS 1 To measure the molar solubility of a sparingly soluble salt in water.

### Beer's Law: Colorimetry of Copper(II) Solutions

Exercise 11 Page 1 Illinois Central College CHEMISTRY 130 Name: Beer's Law: Colorimetry of Copper(II) Solutions Objectives In this experiment, we will use Beer's Law to determine the unknown concentrations

### 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

### Absorbance Spectrophotometry: Analysis of FD&C Red Food Dye #40

Absorbance Spectrophotometry: Analysis of FD&C Red Food Dye #40 Note: there is a second document that goes with this one! 2046 - Absorbance Spectrophotometry - Calibration Curve Procedure. The second document

### 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

### 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

### 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

### Phenolphthalein-NaOH Kinetics

Phenolphthalein-NaOH Kinetics Phenolphthalein is one of the most common acid-base indicators used to determine the end point in acid-base titrations. It is also the active ingredient in some laxatives.

### Austin Peay State University Department of Chemistry Chem 1111. The Use of the Spectrophotometer and Beer's Law

Purpose To become familiar with using a spectrophotometer and gain an understanding of Beer s law and it s relationship to solution concentration. Introduction Scientists use many methods to determine

### EXPERIMENT 11 UV/VIS Spectroscopy and Spectrophotometry: Spectrophotometric Analysis of Potassium Permanganate Solutions.

EXPERIMENT 11 UV/VIS Spectroscopy and Spectrophotometry: Spectrophotometric Analysis of Potassium Permanganate Solutions. Outcomes After completing this experiment, the student should be able to: 1. Prepare

### EXPERIMENT 5. Molecular Absorption Spectroscopy: Determination of Iron With 1,10-Phenanthroline

EXPERIMENT 5 Molecular Absorption Spectroscopy: Determination of Iron With 1,10-Phenanthroline UNKNOWN Submit a clean, labeled 100-mL volumetric flask to the instructor so that your unknown iron solution

### LIGHTSTICK KINETICS. INTRODUCTION: General background on rate, activation energy, absolute temperature, and graphing.

LIGHTSTICK KINETICS From Advancing Science, Gettysburg College INTRODUCTION: General background on rate, activation energy, absolute temperature, and graphing. THE RATE LAW: The rate of a chemical reaction

### Coordination Compounds with Copper (II) Prelab (Week 2)

Coordination Compounds with Copper (II) Prelab (Week 2) Name Total /10 SHOW ALL WORK NO WORK = NO CREDIT 1. What is the purpose of this experiment? 2. Write the generic chemical formula for the coordination

### Endothermic and Exothermic Reactions. Evaluation copy. Mg(s) + 2 HCl(aq) H 2 (g) + MgCl 2 (aq)

Endothermic and Exothermic Reactions Computer 1 Many chemical reactions give off energy. Chemical reactions that release energy are called exothermic reactions. Some chemical reactions absorb energy and

### Net ionic equation: 2I (aq) + 2H (aq) + H O (aq) I (s) + 2H O(l)

Experiment 5 Goals To determine the differential rate law for the reaction between iodide and hydrogen peroxide in an acidic environment. To determine the activation energy and pre-exponential factor for

### Enzyme Action: Testing Catalase Activity 50 Points

Names: LabQuest Enzyme Action: Testing Catalase Activity 50 Points 6A Many organisms can decompose hydrogen peroxide (H 2 O 2 ) enzymatically. Enzymes are globular proteins, responsible for most of the

### 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

### Appendix C. Vernier Tutorial

C-1. Vernier Tutorial Introduction: In this lab course, you will collect, analyze and interpret data. The purpose of this tutorial is to teach you how to use the Vernier System to collect and transfer

### 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

### 1. Qualitative Analysis of Chromium, Iron, and Copper

1. Qualitative Analysis of Chromium, Iron, and Copper Introduction We have used copper and iron as basic materials since the Bronze and Iron Ages, but our extensive use of chromium began only after the

### Honors Chemistry: Unit 6 Test Stoichiometry PRACTICE TEST ANSWER KEY Page 1. A chemical equation. (C-4.4)

Honors Chemistry: Unit 6 Test Stoichiometry PRACTICE TEST ANSWER KEY Page 1 1. 2. 3. 4. 5. 6. Question What is a symbolic representation of a chemical reaction? What 3 things (values) is a mole of a chemical

### Colorimetric Determination of Iron in Vitamin Tablets

Cautions: 6 M hydrochloric acid is corrosive. Purpose: To colorimetrically determine the mass of iron present in commercial vitamin tablets using a prepared calibration curve. Introduction: Iron is considered

### Enzyme Action: Testing Catalase Activity

Enzyme Action: Testing Catalase Activity DataQuest 12 Many organisms can decompose hydrogen peroxide (H 2 O 2 ) enzymatically. Enzymes are globular proteins, responsible for most of the chemical activities

### 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

### 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

### INTRODUCTION TO SPECTROMETRY

Experiment 11 INTRODUCTION TO SPECTROMETRY Portions adapted by Ross S. Nord and Colleagues, Chemistry Department, Eastern Michigan University from ANAL 043, written by Donald F. Clemens and Warren A. McAllister,

### Measuring Protein Concentration through Absorption Spectrophotometry

Measuring Protein Concentration through Absorption Spectrophotometry In this lab exercise you will learn how to homogenize a tissue to extract the protein, and then how to use a protein assay reagent to

### 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

### Unit 2: Quantities in Chemistry

Mass, Moles, & Molar Mass Relative quantities of isotopes in a natural occurring element (%) E.g. Carbon has 2 isotopes C-12 and C-13. Of Carbon s two isotopes, there is 98.9% C-12 and 11.1% C-13. Find

### 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

### Using the Spectrophotometer

Using the Spectrophotometer Introduction In this exercise, you will learn the basic principals of spectrophotometry and and serial dilution and their practical application. You will need these skills to

### 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

### 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

### AP Chemistry 2010 Scoring Guidelines Form B

AP Chemistry 2010 Scoring Guidelines Form B The College Board The College Board is a not-for-profit membership association whose mission is to connect students to college success and opportunity. Founded

### Lab 5: Quantitative Analysis- Phosphates in Water By: A Generous Student. LBS 171L Section 9 TA: Dana October 27, 2005

How uch Phosphate is the Body Being Exposed to During a Lifetime by Showering? Lab 5: Quantitative Analysis- Phosphates in Water By: A Generous Student LBS 171L Section 9 TA: Dana October 7, 005 [Note:

### The Empirical Formula of a Compound

The Empirical Formula of a Compound Lab #5 Introduction A look at the mass relationships in chemistry reveals little order or sense. The ratio of the masses of the elements in a compound, while constant,

### ENZYME ACTION: TESTING CATALASE ACTIVITY

ENZYME ACTION: TESTING CATALASE ACTIVITY LAB ENZ 1.CALC From Biology with Calculators, Vernier Software & Technology, 2000 INTRODUCTION Many organisms can decompose hydrogen peroxide (H 2 O 2 ) enzymatically.

### Experiment 3 Limiting Reactants

3-1 Experiment 3 Limiting Reactants Introduction: Most chemical reactions require two or more reactants. Typically, one of the reactants is used up before the other, at which time the reaction stops. The

### IODINE CLOCK. A Study of Reaction Rates.

IODINE CLOCK A Study of Reaction Rates. In this lab you will be studying the Law of Mass Action. Please review that law in your text in the chapter on Chemical Kinetics. Basically, the law states that

### Laboratory 5: Properties of Enzymes

Laboratory 5: Properties of Enzymes Technical Objectives 1. Accurately measure and transfer solutions with pipettes 2. Use a Spectrophotometer to study enzyme action. 3. Properly graph a set of data. Knowledge

### 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

### THE ACTIVITY OF LACTASE

THE ACTIVITY OF LACTASE Lab VIS-8 From Juniata College Science in Motion Enzymes are protein molecules which act to catalyze the chemical reactions in living things. These chemical reactions make up the

### Pressure -Temperature Relationship in Gases. Evaluation copy. Figure 1. 125 ml Erlenmeyer flask. Vernier computer interface

Pressure -Temperature Relationship in Gases Computer 7 Gases are made up of molecules that are in constant motion and exert pressure when they collide with the walls of their container. The velocity and

### 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

### KINETIC DETERMINATION OF SELENIUM BY VISIBLE SPECTROSCOPY (VERSION 1.8)

Selenium Determination, Page 1 KINETIC DETERMINATION OF SELENIUM BY VISIBLE SPECTROSCOPY I. BACKGROUND. (VERSION 1.8) The majority of reactions used in analytical chemistry possess the following characteristics:

### Spectrophotometry and the Beer-Lambert Law: An Important Analytical Technique in Chemistry

Spectrophotometry and the Beer-Lambert Law: An Important Analytical Technique in Chemistry Jon H. Hardesty, PhD and Bassam Attili, PhD Collin College Department of Chemistry Introduction: In the last lab

### 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

### Stoichiometry Limiting Reagent Laboratory. Chemistry 118 Laboratory University of Massachusetts, Boston

Chemistry 118 Laboratory University of Massachusetts, Boston STOICHIOMETRY - LIMITING REAGENT -----------------------------------------------------------------------------------------------------------------------------

### #02 The Aspirin Shelf-Life Scenario Eugene F. Crabill, East Central High School, St. Leon, IN 47012

INTRODUTION To close the yellow note, click once to select it and then click the box in the upper left corner. To open the note, double click (Mac OS) or right click (Windows) on the note icon. #02 The

### Freezing Point Depression: Why Don t Oceans Freeze? Teacher Advanced Version

Freezing Point Depression: Why Don t Oceans Freeze? Teacher Advanced Version Freezing point depression describes the process where the temperature at which a liquid freezes is lowered by adding another

### 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

### Lab #13: Qualitative Analysis of Cations and Anions

Lab #13: Qualitative Analysis of Cations and Anions Objectives: 1. To understand the rationale and the procedure behind the separation for various cations and anions. 2. To perform qualitative analysis

### EXPERIMENT 7 Reaction Stoichiometry and Percent Yield

EXPERIMENT 7 Reaction Stoichiometry and Percent Yield INTRODUCTION Stoichiometry calculations are about calculating the amounts of substances that react and form in a chemical reaction. The word stoichiometry

### Lab 2. Spectrophotometric Measurement of Glucose

Lab 2 Spectrophotometric Measurement of Glucose Objectives 1. Learn how to use a spectrophotometer. 2. Produce a glucose standard curve. 3. Perform a glucose assay. Safety Precautions Glucose Color Reagent

### SOLUBILITY, IONIC STRENGTH AND ACTIVITY COEFFICIENTS

SOLUBILITY, IONIC STRENGTH AND ACTIVITY COEFFICIENTS References: 1. See `References to Experiments' for text references.. W. C. Wise and C. W. Davies, J. Chem. Soc., 73 (1938), "The Conductivity of Calcium

### Enzyme Action: Testing Catalase Activity

Enzyme Action: Testing Catalase Activity Experiment 6A Many organisms can decompose hydrogen peroxide (H 2 O 2 ) enzymatically. Enzymes are globular proteins, responsible for most of the chemical activities

### Evaluation copy. Enzyme Action: Testing Catalase Activity (Method 1 O 2 Gas Sensor) Computer 2

Enzyme Action: Testing Catalase Activity (Method 1 O 2 Gas Sensor) Computer 2 Many organisms can decompose hydrogen peroxide (H 2 O 2 ) enzymatically. Enzymes are globular proteins, responsible for most

### Tutorial 4 SOLUTION STOICHIOMETRY. Solution stoichiometry calculations involve chemical reactions taking place in solution.

T-27 Tutorial 4 SOLUTION STOICHIOMETRY Solution stoichiometry calculations involve chemical reactions taking place in solution. Of the various methods of expressing solution concentration the most convenient

### 2 Spectrophotometry and the Analysis of Riboflavin

2 Spectrophotometry and the Analysis of Riboflavin Objectives: A) To become familiar with operating the Platereader; B) to learn how to use the Platereader in determining the absorption spectrum of a compound

### Cary 100 Bio UV-Vis Operating Instructions 09/25/2012 S.V.

1234 Hach Hall 515-294-5805 www.cif.iastate.edu Cary 100 Bio UV-Vis Operating Instructions 09/25/2012 S.V. Location: Contact: 1240 Hach Hall Steve Veysey, 1234 Hach Hall Safety All researchers working

### Experiment 4 The Relationship of Density and Molarity of an Aqueous Salt Solution

Experiment 4 The Relationship of Density and Molarity of an Aqueous Salt Solution Purpose: The purpose of this experiment is to investigate the relationship between the concentration of an aqueous salt

### COLORIMETER. Description 0358BT. Figure 1. The Colorimeter

COLORIMETER Description 0358BT Figure 1. The Colorimeter Introduction The Colorimeter is designed to determine the concentration of a solution by analyzing its color intensity. Monochromatic light from

### Similarities The ph of each of these solutions is the same; that is, the [H + ] is the same in both beakers (go ahead and count).

Compare 1 L of acetate buffer solution (0.50 mol of acetic acid and 0.50 mol sodium acetate) to 1 L of HCl solution AcO - AcO - H+ Cl - AcO - AcO - Cl - Cl - AcO - Cl - Cl - Cl - Cl - AcO - AcO - AcO -

### Solution a homogeneous mixture = A solvent + solute(s) Aqueous solution water is the solvent

Solution a homogeneous mixture = A solvent + solute(s) Aqueous solution water is the solvent Water a polar solvent: dissolves most ionic compounds as well as many molecular compounds Aqueous solution:

### Understanding Analytical Chemistry (Weighing, Mixing, Measuring and Evaluating)

Name: Date: Understanding Analytical Chemistry (Weighing, Mixing, Measuring and Evaluating) High School Environmental Science AP Module 1 Environmental Lab NGSSS Big Ideas: This module is a laboratory-based

### Enzyme Action: Testing Catalase Activity

Enzyme Action: Testing Catalase Activity Experiment 6A Many organisms can decompose hydrogen peroxide (H 2 O 2 ) enzymatically. Enzymes are globular proteins, responsible for most of the chemical activities

### MOLAR AND PARTIAL MOLAR VOLUMES IN AQUEOUS SOLUTIONS (10/21/03)

MOLAR AND PARTIAL MOLAR OLUMES IN AQUEOUS SOLUTIONS (10/1/03) QUANTITATIE TECHNIQUES Use of an Analytical Balance Your assignment is to determine the partial molar volumes of solutions of water with an

### 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,

### Determination of the Mass Percentage of Copper in a Penny. Introduction

Determination of the Mass Percentage of Copper in a Penny Introduction This experiment will cost you one penny (\$0.01). The penny must be minted after 1983. Any penny will do; for best results the penny

### Reaction of Magnesium with Hydrochloric Acid (Gas Laws) Chemicals Needed:

Reaction of Magnesium with Hydrochloric Acid (Gas Laws) Your Name: Date: Partner(s) Names: Objectives: React magnesium metal with hydrochloric acid, collecting the hydrogen over water. Calculate the grams

### CHEM 161: Beer s Law and Analysis of a Sports Drink

CHEM 161: Beer s Law and Analysis of a Sports Drink Introduction Although sunlight appears white, it contains a spectrum of colors. A rainbow actually shows this range of colors in visible light: violet,

### DETERMINING THE MASS OF A COPPER ATOM

DETERMINING THE MASS OF A COPPER ATOM LAB ADV.31 From Vernier Software & Technology, 2004 STANDARDS ADDRESSED 3.4.10 A Explains concepts about the structure and properties of matter. 3.4.12 A Apply concepts

### 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,.

### 2.02 DETERMINATION OF THE FORMULA OF A COMPLEX BY SPECTROPHOTOMETRY

2nd/3rd Year Physical Chemistry Practical Course, Oxford University 2.02 DETERMINATION OF THE FORMULA OF A COMPLEX BY SPECTROPHOTOMETRY (4 points) Outline Spectrometry is widely used to monitor the progress

### ENZYME KINETICS ENZYME-SUBSTRATE PRODUCTS

ENZYME KINETICS INTRODUCTION The study of reaction rates catalyzed by enzymes and the factors affecting them is generally referred to as enzyme kinetics. The basic components of an enzyme catalyzed reaction

### EXPERIMENT 7 Electrochemical Cells: A Discovery Exercise 1. Introduction. Discussion

EXPERIMENT 7 Electrochemical Cells: A Discovery Exercise 1 Introduction This lab is designed for you to discover the properties of electrochemical cells. It requires little previous knowledge of electrochemical

### Stoichiometry Limiting Reagent Laboratory. Chemistry 118 Laboratory University of Massachusetts, Boston

Chemistry 118 Laboratory University of Massachusetts, Boston STOICHIOMETRY - LIMITING REAGENT --------------------------------------------------------------------------------------------------------------------------------------------

### 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

### TITRATION OF VITAMIN C

TITRATION OF VITAMIN C Introduction: In this lab, we will be performing two different types of titrations on ascorbic acid, more commonly known as Vitamin C. The first will be an acid-base titration in

### Colorful Iron Complexes

elearning 2009 Introduction Colorful Iron Complexes Transition Metal Complex Ions Publication No. 91857 Easily distinguish between solutions of iron(ii) and iron(iii) ions by performing re-dox reactions

### ACCELERATION DUE TO GRAVITY

ACCELERATION DUE TO GRAVITY Objective: To measure the acceleration of a freely falling body due to gravitational attraction. Apparatus: Computer with Logger Pro, green Vernier interface box, picket fence