Thermochemistry: Enthalpy of Reaction Hess s Law
|
|
- Chad Reed
- 7 years ago
- Views:
Transcription
1 Thermochemistry: Enthalpy of Reaction Hess s Law Objective Demonstrate Hess s Law for determining the enthalpy of formation for MgO by measuring temperature change for several reactions. Introduction The reaction between Mg and O 2 to form MgO is too dangerous for a basic chemistry laboratory. However, you can indirectly calculate the ΔH f of MgO by using Hess s Law. In this experiment, we will determine ΔH for reactions (1) and (2) below, and combine those vlaues with the given enthalpy for reaction (3) to determine the enthalpy of reaction (4). ΔH f for equation (3) is given and will be used in the calculation of ΔH f for MgO(s). Mg (s) + 2 H + (aq) Mg 2+ (aq) + H 2 (g) (1) MgO (s) + 2 H + (aq) Mg 2+ (aq) + H 2O (l) (2) H 2 (g) + ½ O 2 (g) H 2O (l) ΔH f = kj/mole (3) Mg (s) + ½ O 2 (g) MgO (s) (4) The reactions will be run at atmospheric pressure (we can assume that atmospheric pressure will be constant during this experiment). In general, the preferred units are kj for ΔH and kj per mole of compound for ΔH f. The sign of ΔH is relevant since a ΔH > 0 (positive) indicates heat absorbed (endothermic) and a negative ΔH indicates heat is released (exothermic). You will measure heat changes in this experiment by observing the temperature change of the reaction mixture. The reactants are mixed in a calorimeter (dual Styrofoam cup) and the change in the temperature of the reaction mixture is recorded until the temperature stabilizes (and all of the material is consumed). The heat released by the chemical reaction is all absorbed by the contents of the calorimeter, and the calorimeter equipment, resulting in an increase in the temperature of the vessel and its contents. The theoretical amount of heat released by chemical reaction in this experiment is equal to (ΔH) (n), where n is the number of moles of limiting reactant. Consistent with both thermodynamic convention and common usage, we define heat released (heat liberated) as a value less than zero (0) [and therefore equal to (ΔH) (n)].. The following example illustrates the definition. H 2 (g) + ½ O 2 (g) H 2O (l) ΔH f = kj/mole (5) If two moles of hydrogen react with one mole of oxygen to form 2 moles of water, the enthalpy (heat) change is calculated as follows: 1
2 ΔH = ΔH f(n) = kj/mole (2 moles) = kj The heat released is calculated as follows: Heat released = ΔH f (n) = ( kj/mole)(2 moles) = kj Thus we say the heat change of the system was minus kj because the system lost this amount of heat to the surroundings, but the heat released was kj. The heat released by the chemical reaction was absorbed by the experimental equipment (calorimeter plus contents). Part of the heat released by the reaction is gained by the reaction mixture (observed as a change in liquid temperature) and the rest is gained by the walls of the calorimeter (and the thermometer). The heat gained by the reaction mixture is equal to the product of [specific heat of the mixture (sp. ht.)] times [the mass of the reaction mixture] times [the change in temperature]. (Specific heat is defined as the amount of heat required to raise the temperature of one gram of substance one degree Celsius). ΔH rxn mixture = (mass) (sp. ht.) (ΔT) The heat gained by the calorimeter over small temperature ranges is a constant (Cc) times the change in temperature of the reaction mixture. The calorimeter constant, Cc, is specific for your calorimeter; therefore, it is important to use the same calorimeter for all the reactions. The units on the calorimeter constant are J/ C. If we have an adiabatic system, (no heat enters or escapes from the calorimeter) the heat change of the reaction can be approximated by the heat change of the reaction mixture and calorimeter. Mathematically, this is written: n ΔH = (mass) (sp. ht.) (ΔT) + (Cc) (ΔT) (6) (heat released by the reaction) = (heat gained by reaction mixture) + (heat gained by the calorimeter) To solve for ΔH for a reaction, all the other values in the above equation must be determined. The first objective will be to calibrate the calorimeter, and determine the calorimeter constant, Cc. This calibration is accomplished by producing a known quantity of heat (by a chemical reaction of H + and OH - ) from reaction (7) below and measuring ΔT. Since ΔH, the specific heat, and the quantities of NaOH and HCl are known (assuming that all volumes are additive), the only unknown in equation (6) is Cc, which you can now calculate. OH (aq) + H + (aq) H2O (l) ΔH = 57.7 kj/mole (7) Once the value of Cc is found, it can be used in reactions (1) and (2) to solve for the unknown heat of reaction, ΔH. 2
3 During this experiment you will measure and record the temperature at given time intervals. This data will be plotted on a graph of temperature versus time (as shown on the following page) to determine the maximum temperature for the reaction. Notice the temperature vs. time plot will be irregular until it stabilizes on a slowly decreasing temperature line. This irregular behavior is due to the calorimeter s inability to absorb heat as quickly as the reaction mixture releases it. However, accurate results can be obtained by extrapolating the temperature data to time zero (depicted in Figure 1). The correct temperature change, ΔT, is determined by subtracting the initial temperature (T i) from the extrapolated high temperature (T extrapolated). Skills: Quantitative Measurements Lab equipment: Scales, calorimeters Quantitative measurements Volumetric measurements Handling of chemicals Calculations Graphing of data Equipment & Reagents Calorimeter Distilled water Precision thermometer Clock or stopwatch 100 ml graduated cylinder Mg turnings 1M HCl MgO 1M NaOH Figure 1: Plot of Temperature versus time for the reaction of HCl with NaOH. 3
4 Procedure Part A: Calorimeter Calibration (finding Cc) 1. Choose a calorimeter and ensure the calorimeter and thermometer are clean and have been rinsed with distilled water. Using a 100 ml graduated cylinder, measure 50.0 ml of the approximately 1M HCl, then pour the HCl into the calorimeter. 2. Record the exact molarity found on the HCl storage bottle. 3. Insert the thermometer assembly and record the temperature when it stabilizes (less than 3 minutes). Measure all temperatures to the nearest 0.01 C with the aid of a special thermometer. WARNING: Precision thermometers are expensive. Treat them with care. DO NOT USE THE THERMOMETER TO STIR THE MIXTURE!!!!! If you break a thermometer, tell the instructor or lab assistant so they can have the mercury spill cleaned up. Also, HCl stains bench tops, books, and clothing; clean up spills immediately! 4. Rinse the graduated cylinder successively with tap water, distilled water, and 5 ml of 1M NaOH solution. 5. Measure 50.0 ml of NaOH solution in the graduated cylinder and, noting the time, pour the NaOH into the calorimeter. Immediately insert the thermometer assembly and gently swirl the reactants. 6. Record the temperature to the nearest 0.05 C at ½-minute intervals until a maximum is reached; then record at one minute intervals until enough data is obtained for an extrapolation (generally ~ 5 to 10 minutes). Gently swirl the reaction mixture before each reading. Heat of Reaction of Mg and HCl 1. Using a graduated cylinder, measure 50.0 ml of the 1M HCl and 50.0 ml of distilled water into the same clean, dry calorimeter used above and measure the stabilized temperature. 2. Weigh 0.20 to 0.30 g of Mg turnings to the nearest milligram on the balance. 3. Noting the time (t=0), drop the Mg into the calorimeter. Immediately put the thermometer assembly in place and swirl gently. DO NOT USE THE THERMOMETER TO STIR THE MIXTURE!!!!! 4. Record the temperature at ½-minute intervals until a maximum is reached. Then record at one minute intervals for at least 5 minutes. Gently swirl the reaction mixture between each reading. 4
5 Heat of Reaction of MgO and HCl 1. Repeat the above steps (1-4) using MgO in place of Mg. Use 0.50 to 0.60 g MgO, weighed to the nearest milligram. Be sure to use the same calorimeter. NOTE: You must swirl the calorimeter vigorously while reacting MgO and HCl since the MgO tends to form lumps at the bottom of the calorimeter and fails to dissolve. This could cause considerable error with appropriate impact on your grade. Hold the temperature assembly in the calorimeter so it will not break while swirling. When it appears that temperature changes have ceased, quickly look into the calorimeter. If there is still white solid at the bottom, the calorimeter must be swirled more vigorously until all the MgO has dissolved. Cleanup Clean your lab area, calorimeter, and glassware before being signed out by your lab assistant. Write-up As a critical part of the lab write-up, you will need to present your data from each of the experimental runs graphically (three separate plots), clearly indicating the final, initial, and change in temperature on each of the plots. To do this, we will rely on the Graphical Analysis computer program (or MS Excel, or any appropriate graphing program). MAKE SURE THAT YOU INCLUDE ALL APPROPRIATE INFORMATION ON THE PLOT TO ENSURE THAT THE PLOTS STAND ALONE AND CONVEY APPROPRIATE INFORMATION. If I presented your plots back to you at a later date, could you understand the data/information presented? Each student must include plots of their data as a part of the lab write-up. Calculations You must show the appropriate representative calculations (using your data) for each of the calculations below. These calculations may be NEATLY hand-written, and forego the routine type-written requirement. It goes without saying that you must explicitly indicate the units used for each calculation. 1. Determine the calorimeter constant, Cc, for the calorimeter you used. 2. Determine ΔH for the reaction of Mg(s) with HCl(aq). (Equation 1) 3. Determine ΔH for the reaction of MgO(s) with HCl(aq). (Equation 2) 4. Calculate ΔH f for MgO(s). (Equation 4) 5
6 Post Lab Questions (Answer the following questions, making sure to give me a good indication of the question, your answer, AND your rationale). 1. If heat is conserved, why does the calorimeter cool down? 2. If ΔH were not a state function, would this technique be valid? Explain. 3. How would the overall (net) results be affected if we doubled the amount of MgO or Mg? 4. If all of the MgO in the calorimeter has not reacted when you stop taking data, how will your final results be affected? 6
7 5. Report: Hess's Law Name Lab Partner(s) Section Date performed Part I: Calorimeter Calibration Data Volume of acid ml Temperature of acid and calorimeter C Volume of base ml Temperature of base C Avg. Temp of acid and base (before mixing) C Temperature vs. time after mixing of HCl and NaOH: (The first time/temp block should be the time = 0 (average temperature from above). Time Temp Time Temp Time Temp Time Temp Time Temp 0 Specific heat of reaction mixture J/g C (Given) 7
8 Part II & III: Heats of Reaction Data Part II Part III Mg & HCl MgO & HCl Volume of acid in calorimeter ml ml Volume of water in calorimeter ml ml Temperature of solution at equilibrium (Ti) C C Mass of solid reactant g g Temperature vs. time after mixing: Mg & HCl Time Temp Time Temp Time Temp Time Temp Time Temp 0 MgO & HCl Time Temp Time Temp Time Temp 0 Specific heat of reaction mixture Mg & HCl J/g C (Given) MgO & HCl J/g C (Given) NOTE: The sign of ΔH must be taken into account for all calculations. 8
Transfer of heat energy often occurs during chemical reactions. A reaction
Chemistry 111 Lab: Thermochemistry Page I-3 THERMOCHEMISTRY Heats of Reaction The Enthalpy of Formation of Magnesium Oxide Transfer of heat energy often occurs during chemical reactions. A reaction may
More informationDETERMINING THE ENTHALPY OF FORMATION OF CaCO 3
DETERMINING THE ENTHALPY OF FORMATION OF CaCO 3 Standard Enthalpy Change Standard Enthalpy Change for a reaction, symbolized as H 0 298, is defined as The enthalpy change when the molar quantities of reactants
More informationThermochemistry: Calorimetry and Hess s Law
Thermochemistry: Calorimetry and Hess s Law Some chemical reactions are endothermic and proceed with absorption of heat while others are exothermic and proceed with an evolution of heat. The magnitude
More informationThermochemistry I: Endothermic & Exothermic Reactions
THERMOCHEMISTRY I 77 Thermochemistry I: Endothermic & Exothermic Reactions OBJECTIVES: Learn elementary concepts of calorimetry and thermochemistry Practice techniques of careful temperature, mass, and
More informationExperiment 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 informationHEAT OF FORMATION OF AMMONIUM NITRATE
303 HEAT OF FORMATION OF AMMONIUM NITRATE OBJECTIVES FOR THE EXPERIMENT The student will be able to do the following: 1. Calculate the change in enthalpy (heat of reaction) using the Law of Hess. 2. Find
More informationExp 13 Volumetric Analysis: Acid-Base titration
Exp 13 Volumetric Analysis: Acid-Base titration Exp. 13 video (time: 47:17 minutes) Titration - is the measurement of the volume of a standard solution required to completely react with a measured volume
More informationApparatus error for each piece of equipment = 100 x margin of error quantity measured
1) Error Analysis Apparatus Errors (uncertainty) Every time you make a measurement with a piece of apparatus, there is a small margin of error (i.e. uncertainty) in that measurement due to the apparatus
More informationPREPARATION FOR CHEMISTRY LAB: COMBUSTION
1 Name: Lab Instructor: PREPARATION FOR CHEMISTRY LAB: COMBUSTION 1. What is a hydrocarbon? 2. What products form in the complete combustion of a hydrocarbon? 3. Combustion is an exothermic reaction. What
More informationDetermination 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 informationAcid 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 informationThermochemical equations allow stoichiometric calculations.
CHEM 1105 THERMOCHEMISTRY 1. Change in Enthalpy ( H) Heat is evolved or absorbed in all chemical reactions. Exothermic reaction: heat evolved - heat flows from reaction mixture to surroundings; products
More informationDetermination of the enthalpy of combustion using a bomb calorimeter TEC
Determination of the enthalpy of TEC Related concepts First law of thermodynamics, Hess s law of constant heat summation, enthalpy of combustion, enthalpy of formation, heat capacity. Principle The bomb
More informationthermometer as simple as a styrofoam cup and a thermometer. In a calorimeter the reactants are placed into the
Thermochemistry Readin assinment: Chan, Chemistry 10 th edition, pp. 249-258. Goals We will become familiar with the principles of calorimetry in order to determine the heats of reaction for endothermic
More informationExperiment 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 informationPhysical Properties of a Pure Substance, Water
Physical Properties of a Pure Substance, Water The chemical and physical properties of a substance characterize it as a unique substance, and the determination of these properties can often allow one to
More informationDetermining 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 informationHeat of Solution. Purpose To calculate the heat of solution for sodium hydroxide (NaOH) and ammonium nitrate (NH 4 NO 3 )
Heat of Solution Purpose To calculate the heat of solution for sodium hydroxide (NaOH) and ammonium nitrate (NH 4 NO 3 ) Background For a given solute, the heat of solution is the change in enerrgy that
More informationThermochemistry. r2 d:\files\courses\1110-20\99heat&thermorans.doc. Ron Robertson
Thermochemistry r2 d:\files\courses\1110-20\99heat&thermorans.doc Ron Robertson I. What is Energy? A. Energy is a property of matter that allows work to be done B. Potential and Kinetic Potential energy
More informationTo 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 informationDetermination of the enthalpy of combustion using a bomb calorimeter TEC. Safety precautions
Safety precautions Naphthalene is harmful if swallowed. May cause cancer. Is further very toxic to aquatic organisms and can have long-term harmful effects in bodies of water. Equipment 1 Bomb calorimeter
More informationEXPERIMENT 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
More informationReaction 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
More informationNet 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
More informationEXPERIMENT 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 informationEndothermic 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
More informationEvaluation 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 informationExperiment 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
More informationChemistry 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 informationStoichiometry Limiting Reagent Laboratory. Chemistry 118 Laboratory University of Massachusetts, Boston
Chemistry 118 Laboratory University of Massachusetts, Boston STOICHIOMETRY - LIMITING REAGENT -----------------------------------------------------------------------------------------------------------------------------
More informationUnit 5 Practice Test. Name: Class: Date: Multiple Choice Identify the choice that best completes the statement or answers the question.
Name: Class: Date: Unit 5 Practice Test Multiple Choice Identify the choice that best completes the statement or answers the question. 1) The internal energy of a system is always increased by. A) adding
More informationMixing Warm and Cold Water
Mixing Warm and Cold Water A Continuing Investigation of Thermal Pollution By Kevin White 1 Context: This lesson is intended for students conducting an ongoing study of thermal pollution. Perhaps, students
More informationThe 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,
More informationPhenolphthalein-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.
More informationACID-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 informationChemistry B11 Chapter 4 Chemical reactions
Chemistry B11 Chapter 4 Chemical reactions Chemical reactions are classified into five groups: A + B AB Synthesis reactions (Combination) H + O H O AB A + B Decomposition reactions (Analysis) NaCl Na +Cl
More informationBLOWING UP BALLOONS, chemically
BLOWING UP BALLOONS, chemically PRE LAB DISCUSSION: Today we will be using a closed system. A closed system does not permit matter to enter or exit the apparatus. Lavoisier's classic 12-day experiment,
More informationMolar Mass and the Ideal Gas Law Prelab
Molar Mass and the Ideal Gas Law Prelab Name Total /10 SHOW ALL WORK NO WORK = NO CREDIT 1. What is the purpose of this experiment? 2. Determine the mass (in grams) of magnesium metal required to produce
More informationCOMMON 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 informationDissolving 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 informationLab #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 informationEXPERIMENT 12: Empirical Formula of a Compound
EXPERIMENT 12: Empirical Formula of a Compound INTRODUCTION Chemical formulas indicate the composition of compounds. A formula that gives only the simplest ratio of the relative number of atoms in a compound
More informationPre-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 informationAscorbic 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 informationUNIT 1 THERMOCHEMISTRY
UNIT 1 THERMOCHEMISTRY THERMOCHEMISTRY LEARNING OUTCOMES Students will be expected to: THERMOCHEMISTRY STSE analyse why scientific and technological activities take place in a variety individual and group
More informationBomb Calorimetry. Example 4. Energy and Enthalpy
Bomb Calorimetry constant volume often used for combustion reactions heat released by reaction is absorbed by calorimeter contents need heat capacity of calorimeter q cal = q rxn = q bomb + q water Example
More informationph: 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 informationFreezing 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
More informationChemistry 212 VAPOR PRESSURE OF WATER LEARNING OBJECTIVES
Chemistry 212 VAPOR PRESSURE OF WATER LEARNING OBJECTIVES The learning objectives of this experiment are to explore the relationship between the temperature and vapor pressure of water. determine the molar
More informationGeneral Chemistry I (FC, 09-10) Lab #3: The Empirical Formula of a Compound. Introduction
General Chemistry I (FC, 09-10) 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, does not
More informationSTANDARDIZATION 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 informationModule 5: Combustion Technology. Lecture 34: Calculation of calorific value of fuels
1 P age Module 5: Combustion Technology Lecture 34: Calculation of calorific value of fuels 2 P age Keywords : Gross calorific value, Net calorific value, enthalpy change, bomb calorimeter 5.3 Calculation
More informationDetermination 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 informationTo 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 informationEXPERIMENT 9 Evaluation of the Universal Gas Constant, R
Outcomes EXPERIMENT 9 Evaluation of the Universal Gas Constant, R After completing this experiment, the student should be able to: 1. Determine universal gas constant using reaction of an acid with a metal.
More informationStoichiometry Limiting Reagent Laboratory. Chemistry 118 Laboratory University of Massachusetts, Boston
Chemistry 118 Laboratory University of Massachusetts, Boston STOICHIOMETRY - LIMITING REAGENT --------------------------------------------------------------------------------------------------------------------------------------------
More informationCHEMICAL REACTIONS OF COPPER AND PERCENT YIELD KEY
CHEMICAL REACTIONS OF COPPER AND PERCENT YIELD Objective To gain familiarity with basic laboratory procedures, some chemistry of a typical transition element, and the concept of percent yield. Apparatus
More informationEnergy and Chemical Reactions. Characterizing Energy:
Energy and Chemical Reactions Energy: Critical for virtually all aspects of chemistry Defined as: We focus on energy transfer. We observe energy changes in: Heat Transfer: How much energy can a material
More informationThe Molar Mass of a Gas
The Molar Mass of a Gas Goals The purpose of this experiment is to determine the number of grams per mole of a gas by measuring the pressure, volume, temperature, and mass of a sample. Terms to Know Molar
More informationExperiment 1: Colligative Properties
Experiment 1: Colligative Properties Determination of the Molar Mass of a Compound by Freezing Point Depression. Objective: The objective of this experiment is to determine the molar mass of an unknown
More informationChemistry 101 Generating Hydrogen Gas
Chemistry 101 Generating Hydrogen Gas Objectives To experimentally verify the molar volume of hydrogen gas at STP To gain experience in collecting gas over water Discussion The molar volume of a gas is
More informationEXPERIMENT 15: Ideal Gas Law: Molecular Weight of a Vapor
EXPERIMENT 15: Ideal Gas Law: Molecular Weight of a Vapor Purpose: In this experiment you will use the ideal gas law to calculate the molecular weight of a volatile liquid compound by measuring the mass,
More informationCSUS Department of Chemistry Experiment 8 Chem.1A
EXPERIMENT #8 Name: PRE-LABORATORY ASSIGNMENT: Lab Section 1. The alkali metals are so reactive that they react directly with water in the absence of acid. For example, potassium reacts with water as follows:
More informationHonors 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
More informationIn this experiment, we will use three properties to identify a liquid substance: solubility, density and boiling point..
Identification of a Substance by Physical Properties 2009 by David A. Katz. All rights reserved. Permission for academic use provided the original copyright is included Every substance has a unique set
More informationCHEM 105 HOUR EXAM III 28-OCT-99. = -163 kj/mole determine H f 0 for Ni(CO) 4 (g) = -260 kj/mole determine H f 0 for Cr(CO) 6 (g)
CHEM 15 HOUR EXAM III 28-OCT-99 NAME (please print) 1. a. given: Ni (s) + 4 CO (g) = Ni(CO) 4 (g) H Rxn = -163 k/mole determine H f for Ni(CO) 4 (g) b. given: Cr (s) + 6 CO (g) = Cr(CO) 6 (g) H Rxn = -26
More informationWhere the exp subscripts refer to the experimental temperature and pressure acquired in the laboratory.
Molar Volume of Carbon Dioxide Reading assignment: Julia Burdge, Chemistry 3rd edition, Chapter 10. Goals To determine the molar volume of carbon dioxide gas and the amount of sodium carbonate in a sample.
More informationDetermination 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 informationENTHALPY CHANGES FOR A CHEMICAL REACTION scaling a rxn up or down (proportionality) quantity 1 from rxn heat 1 from Δ r H. = 32.
CHEMISTRY 103 Help Sheet #10 Chapter 4 (Part II); Sections 4.6-4.10 Do the topics appropriate for your lecture Prepared by Dr. Tony Jacob http://www.chem.wisc.edu/areas/clc (Resource page) Nuggets: Enthalpy
More informationAustin Peay State University Department of Chemistry CHEM 1111. Empirical Formula of a Compound
Cautions Magnesium ribbon is flammable. Nitric acid (HNO 3 ) is toxic, corrosive and contact with eyes or skin may cause severe burns. Ammonia gas (NH 3 ) is toxic and harmful. Hot ceramic crucibles and
More informationHands-On Labs SM-1 Lab Manual
EXPERIMENT 4: Separation of a Mixture of Solids Read the entire experiment and organize time, materials, and work space before beginning. Remember to review the safety sections and wear goggles when appropriate.
More information15. 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 informationThermodynamics. Thermodynamics 1
Thermodynamics 1 Thermodynamics Some Important Topics First Law of Thermodynamics Internal Energy U ( or E) Enthalpy H Second Law of Thermodynamics Entropy S Third law of Thermodynamics Absolute Entropy
More informationEnzyme 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
More informationChemistry 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 informationExperiment 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 informationTest Review # 9. Chemistry R: Form TR9.13A
Chemistry R: Form TR9.13A TEST 9 REVIEW Name Date Period Test Review # 9 Collision theory. In order for a reaction to occur, particles of the reactant must collide. Not all collisions cause reactions.
More informationPART I SIEVE ANALYSIS OF MATERIAL RETAINED ON THE 425 M (NO. 40) SIEVE
Test Procedure for PARTICLE SIZE ANALYSIS OF SOILS TxDOT Designation: Tex-110-E Effective Date: August 1999 1. SCOPE 1.1 This method covers the quantitative determination of the distribution of particle
More informationEnzyme 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
More informationLab #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
More informationSample Problem: STOICHIOMETRY and percent yield calculations. How much H 2 O will be formed if 454 g of. decomposes? NH 4 NO 3 N 2 O + 2 H 2 O
STOICHIOMETRY and percent yield calculations 1 Steps for solving Stoichiometric Problems 2 Step 1 Write the balanced equation for the reaction. Step 2 Identify your known and unknown quantities. Step 3
More informationBomb Calorimetry. Electrical leads. Stirrer
Bomb Calorimetry Stirrer Electrical leads Oxygen inlet valve Bomb Fuse Calorimeter Outer jacket Not shown: heating and cooling system for outer jacket, and controls that keep the outer jacket at the same
More informationNeutralization 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 informationEXPERIMENT 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 informationAdiabatic Bomb Calorimetry
CHEM 366 II-1 Adiabatic Bomb Calorimetry Introduction Obtaining energy in the form of heat from the combustion or oxidation of thermodynamically unstable (and often kinetically inert) hydrocarbons and
More informationMeasurement and Calibration
Adapted from: H. A. Neidig and J. N. Spencer Modular Laboratory Program in Chemistry Thompson Learning;, University of Pittsburgh Chemistry 0110 Laboratory Manual, 1998. Purpose To gain an understanding
More informationPHYSICAL SEPARATION TECHNIQUES. Introduction
PHYSICAL SEPARATION TECHNIQUES Lab #2 Introduction When two or more substances, that do not react chemically, are blended together, the result is a mixture in which each component retains its individual
More information5. Which temperature is equal to +20 K? 1) 253ºC 2) 293ºC 3) 253 C 4) 293 C
1. The average kinetic energy of water molecules increases when 1) H 2 O(s) changes to H 2 O( ) at 0ºC 3) H 2 O( ) at 10ºC changes to H 2 O( ) at 20ºC 2) H 2 O( ) changes to H 2 O(s) at 0ºC 4) H 2 O( )
More informationEnthalpy of Combustion via Calorimetry
Enthalpy of Combustion via Calorimetry Introduction This experiment measures the enthalpy change when a system consisting of a known amount of a substance in the presence of excess oxygen is quantitatively
More informationVitamin C Content of Fruit Juice
1 Vitamin C Content of Fruit Juice Introduction Vitamin C Vitamins are organic compounds that have important biological functions. For instance, in humans they enable a variety of enzymes in the body to
More informationHeat of Combustion PCh 6-99
UMR ChemLabs Heat of Combustion PCh 6-99 Gary L. Bertrand, Professor of Chemistry A calorimeter (calor L = heat + metron Gr = measure) should be literally a device to measure heat. In reality, most calorimeters
More informationEnzyme Pre-Lab. Using the Enzyme worksheet and Enzyme lab handout answer the Pre-Lab questions the pre-lab must be complete before beginning the lab.
Enzyme Pre-Lab Using the Enzyme worksheet and Enzyme lab handout answer the Pre-Lab questions the pre-lab must be complete before beginning the lab. Background: In this investigation, you will study several
More informationPART I: PREPARATION OF SOLUTIONS AND STANDARDIZATION OF A BASE
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 informationMaterials 10-mL graduated cylinder l or 2-L beaker, preferably tall-form Thermometer
VAPOR PRESSURE OF WATER Introduction At very low temperatures (temperatures near the freezing point), the rate of evaporation of water (or any liquid) is negligible. But as its temperature increases, more
More informationExperiment 12E LIQUID-VAPOR EQUILIBRIUM OF WATER 1
Experiment 12E LIQUID-VAPOR EQUILIBRIUM OF WATER 1 FV 6/26/13 MATERIALS: PURPOSE: 1000 ml tall-form beaker, 10 ml graduated cylinder, -10 to 110 o C thermometer, thermometer clamp, plastic pipet, long
More informationexperiment5 Understanding and applying the concept of limiting reagents. Learning how to perform a vacuum filtration.
81 experiment5 LECTURE AND LAB SKILLS EMPHASIZED Synthesizing an organic substance. Understanding and applying the concept of limiting reagents. Determining percent yield. Learning how to perform a vacuum
More informationSTATE UNIVERSITY OF NEW YORK COLLEGE OF TECHNOLOGY CANTON, NEW YORK COURSE OUTLINE CHEM 150 - COLLEGE CHEMISTRY I
STATE UNIVERSITY OF NEW YORK COLLEGE OF TECHNOLOGY CANTON, NEW YORK COURSE OUTLINE CHEM 150 - COLLEGE CHEMISTRY I PREPARED BY: NICOLE HELDT SCHOOL OF SCIENCE, HEALTH, AND PROFESSIONAL STUDIES SCIENCE DEPARTMENT
More informationSYNTHESIS AND ANALYSIS OF A COORDINATION COMPOUND OF COPPER
Chemistry 111 Lab: Synthesis of a Copper Complex Page H-1 SYNTHESIS AND ANALYSIS OF A COORDINATION COMPOUND OF COPPER In this experiment you will synthesize a compound by adding NH 3 to a concentrated
More informationThe energy level diagram for this reaction is shown below.
Q. Methanol can be made when methane reacts with oxygen. (a) The energy level diagram for this reaction is shown below. (i) What is the energy change represented by A? () (ii) Use the energy level diagram
More informationExperiment 8: Chemical Moles: Converting Baking Soda to Table Salt
Experiment 8: Chemical Moles: Converting Baking Soda to Table Salt What is the purpose of this lab? We want to develop a model that shows in a simple way the relationship between the amounts of reactants
More information