Lab 5: Calculating an equilibrium constant
|
|
- Laurel Marsh
- 5 years ago
- Views:
Transcription
1 Chemistry 162 The following write-up is inaccurate for the particular chemicals we are using. Please have all sections up through and including the data tables ready before class on Wednesday, February 27. As usual, please write an abstract and paper-clip it to the front of your individual writeup. The abstract and the carbon-copy pages of the write-up is due in class on Wednesday, March 6. Lab 5: Calculating an equilibrium constant Introduction: Indicators are substances whose solutions change color due to changes in ph. They are usually weak acids or bases, but their conjugate base and acid forms have different colors due to differences in their absorption spectra. Indicators are typically weak acids or bases with complicated structures. For simplicity, we represent a general indicator by the formula HIn, and its ionization in a solution by the equilibrium equation: The equilibrium constant for this reaction (Keq) can be written omitting the water, since it is a pure substance. In this experiment we will determine the equilibrium constant (Keq) for the indicator bromothymol blue using a spectrophotometer and a ph meter. Keep in mind that bromothymol blue is blue when in the basic form (In 2- ) and yellow when in the acidic form (HIn - ). The balanced reaction for bromothymol blue s dissociation is: Note that the undissociated bromothymol blue (left) starts already as an anion, and proceeds to become a dissociated divalent anion (right). To measure how much bromothymol blue is in a given solution, you will use the measurements of a spectrophotometer on the bromothymol blue and Beer s Law: The absorbance (A) is the product of three factors, the concentration of the measured species (c), the molar extinction coefficient (ε) and the length of the path the light beam must travel through the solution (l). Since ε and l are fixed for a particular spectrophotometer and chemical species, Beer s Law reduces to the simple notion that the absorbance measured is proportional to the concentration of the measured species. Further complicating this experiment is the observation that bromothymol blue changes color depending on the acidity of the solution. At some wavelengths bromothymol blue
2 will absorb light intensely while at others it will be nearly completely transparent. Our goal is to tune the instrument to the wavelength that will give us the best signal. This will be accomplished by testing our calibration solutions and selecting the wavelength of maximum absorbance (λ max) for both the basic (blue) form and acidic (yellow) form. By using strongly acidic or basic solutions, we can shift the equilibrium nearly completely toward the basic or acidic forms of the indicator. The spectrophotometer should be set to record absorbance (A), but sometimes they are setup to record percent transmittance (%T), which is an intuitively easier concept. The conversion from %T to A is given by the following formula: Lab 5: Calculating an equilibrium constant Part 1. Purpose One goal is to calculate the equilibrium constant of the dissociation of bromothymol blue; you can certainly write that. But another goal is the method that you are using to figure out that constant. In your own words, add a sentence explaining succinctly what you will be looking for. At the bottom of this section, write the balanced equation for the reaction, then add the mathematical expression for calculating the reaction s equilibrium constant. Part 2. Materials and methods Spectrovis spectrophotometer and laptop Lots of 4.5 ml cuvettes M bromothymol blue solution M hydrochloric acid M sodium hydroxide solution Distilled water Digital ph meter Many test tubes 0.10 M K2HPO4 solution 0.10 M KH2PO4 solution Make a sketch of the experimental setup to be used. Each sketch should have the various components labeled. Part 3. Procedure and Observational Data Caution: Dispose of all solutions (including unused ones) in the waste beaker provided.
3 Phase 1 Determining the wavelengths of maximum absorption 1. Prepare six calibration solutions in medium-size test tubes using the 1 and 5 ml graduated pipettes. Stock solutions are those that are provided with the lab. Calibration solution Stock bromothymol blue (ml) Stock hydrochloric acid (ml) C C C Calibration solution Stock bromothymol blue (ml) C C C Stock sodium hydroxide sol n (ml) 2. Obtain a spectrophotometer (SpectroVis) and computer. Turn on the computer and attach the spectrometer via USB cable. Click on the Logger Pro icon on the desktop to initiate the spectroscopy software. 3. Once the software is up and running it is necessary to calibrate the spectrophotometer. To calibrate the SpectroVis, choose Calibrate Spectometer:1 from the Experiment menu. 5. Fill a clean cuvette about ¾ full with distilled water and place it in the sample chamber of the spectrophotometer. Follow the instructions in the dialog box to complete
4 the calibration, and then click OK. After calibrating the spectrophotometer you will be ready to collect data (there may be some last minute set-up instruction from the instructor, so this is a good point to check with the instructor). Remember to handle the cuvette on its ridged sides, not its clear sides. 6. Fill a clean cuvette about ¾ full with solution C1 and place it in the sample chamber of the spectrophotometer. Click Collect to begin data collection. 7. Click Stop to end data collection. Save the spectrum onto your flash drive (in non-.cmbl format); record the filename in your notebook. Also record λ max for this species (use either the mouse or the table to determine this). 8. Fill a clean cuvette about ¾ full with solution C4 and place it in the sample chamber of the spectrophotometer. Click Collect to begin data collection. 9. Click Stop to end data collection. Save the spectrum onto your flash drive (in non-.cmbl format); record the filename in your notebook. Also record λ max for this species (use either the mouse or the table to determine this). Phase 2 Determining the proportionality constant in Beer s Law 10. Set the instrument to the wavelengths of maximum absorbance determined in Part 1, by clicking on the Configure Spectrometer Data Collection button. Then select Abs vs. Concentration as the collection mode. Then change the Column Name to Sample #, the Short Name to sample, and delete the Units. 11. Select the maximum absorbance(s) desired, then click OK.
5 12. Fill your cuvette(s) about ¾ full with your solution(s); you should run all of your C solutions. Insert your sample into the sample holder and click Collect. When reading stabilizes, click Keep. Enter Sample # and click OK. 13. Repeat these steps until all samples have been read on the spectrometer. 14. Click Stop to end data collection; save the data and record the name of the file. Phase 3 Taking measurements from which the equilibrium constant is calculated 15. Prepare five standard solutions in medium-sized test tubes using 1 and 5 ml graduated pipettes, according to the table below: Standard solution Stock bromothymol blue (ml) Stock K2HPO4 solution (ml) Stock KH2PO4 solution (ml) S S S S S Since the spectrophotometer is still calibrated, fill your cuvette(s) about ¾ full with your solution(s); you should run all of your S solutions. Insert your sample into the sample holder and click Collect. When reading stabilizes, click Keep. Enter Sample # and click OK. After reading the sample absorbance, return the sample to its original test tube (i.e., don t throw it into the waste beaker yet). 17. Repeat these steps until all samples have been read on the spectrometer. 18. Click Stop to end data collection; save the data and record the name of the file. 19. Your instructor will show you how to calibrate the digital ph meters, if needed. Follow the instructions given to measure and record the ph of each of the S solutions. Remember to rinse the ph electrode in between measurements. Part 4. Original data and preliminary analysis You ll need to be careful in this section to lay out enough space ahead of time. For Phase 1, you ll want enough space to tape the two (C1 and C4) spectra into the notebook, along with a title or label for each one. You ll also want to mark λ max on each spectrum. For Phase 2, you ll want a table that has headings calibration solution, bromothymol blue concentration, and absorbance, with units, and all the numbers.
6 For Phase 3, you ll want a table that has headings standard solution, ph, and absorbance, with units, and all the numbers. Part 5. Calculated results Show the calculation of the Beer s Law proportionality constant for both the acidic and basic forms of bromothymol blue; make sure to include units. Make sure to recast the Beer s Law equation to indicate what you are doing. Make a plot of bromothymol blue concentration (x-axis) versus absorbance (y-axis) for the Phase 2 data. Use an overlay because you will be plotting both the acidic and basic form absorbances on this graph. Include a title, label axes and all the other features of a good graph. Draw a best-fit line for your points, and include the correlation coefficient (though with so few points, it s a bit meaningless). Make a table of your Phase 3 data that shows [H + ], [HBTB ], [BTB 2 ] and the equilibrium constant Keq. Below, for one of the rows of the table, explain how you calculated or derived each of the concentrations, referring to the calibration plot as necessary in the explanation. Determine your team s avarage Keq for bromothymol blue at room temperature. Explain any outliers you choose to omit from your calculation of this average. Find a reference that gives a published Keq (big hint: it may be called Ka ), cite the reference in the usual style, and calculate a percent error. Part 6. Group results Enter your group s average Keq on the spreadsheet. Calculate the mean and standard deviation of Keq for all groups. Comment on any outliers (which may even be your own values!) and state whether they were used in the calculation. Calculate the percent error for the class from the published value in Part 5. Part 7. Questions 1. Ideally, what shape does Beer s Law suggest that your calibration curve should have been? In your graph, were there any deviations from this ideal behavior? If so, suggest a reason for the deviation.
7 2. Background subtraction is a commonly-applied step on many spectroscopy experiments. What was the background, if any, in this experiment? How did you correct for it? Part 8. Conclusion First paragraph: Report your team s λ max values for both the acidic and basic forms of bromothymol blue. Give a brief description of how you obtained these values, and how confident you are of them. Note any problems that might cause you to doubt these numbers. Second paragraph: Report your team s Beer s Law proportionality constants for both the acidic and basic forms of bromothymol blue. Give a brief description of how you obtained these values, and how confident you are of them. Note any problems that might cause you to doubt these numbers. Third paragraph: Report your team s average Keq of bromothymol and the percent error from the published value. Note any problems that might cause you to doubt this number. Final paragraph: How confident overall are you of your results? In other words, was this a good experimental setup? Were there clear random or systematic errors, and, if so, how could they be corrected? Abstract In the standard abstract format and in a hundred words or less, state the class s equilibrium constant for bromothymol blue and the standard deviation, and report the percent error from the published value. Briefly summarize the manner in which it was measured. Report any major random or systematic errors, and note how this (these) error(s) would lead to the results you have reported.
For simplicity, we ll represent BTB s ionization in a solution by the equilibrium: HBTB = H + + BTB -
Chemistry 160 Please have the following pages ready before class on Wednesday, April 11. An abstract (see the end of this handout) is needed for this write-up. The abstract and photocopied pages of the
More informationDetermination of the Equilibrium Constant. HIn - + H 2 O = H 3 O + + In 2-, [H 3 O + ][In 2- ] K ai = [HIn - ]
Determination of the Equilibrium Constant Introduction Indicators are substances whose solutions change color due to changes in ph. They are usually weak acids or bases, but their conjugate base and acid
More informationExperiment 2: The Beer-Lambert Law for Thiocyanatoiron (III)
Chem 1B Saddleback College Dr. White 1 Experiment 2: The Beer-Lambert Law for Thiocyanatoiron (III) Objectives To use spectroscopy to relate the absorbance of a colored solution to its concentration. To
More informationExperiment 2: The Beer-Lambert Law for Thiocyanatoiron (III)
Chem 1B Dr. White 11 Experiment 2: The Beer-Lambert Law for Thiocyanatoiron (III) Objectives To use spectroscopy to relate the absorbance of a colored solution to its concentration. To prepare a Beer s
More informationExperiment 1 Chemical Kinetics 1
Experiment 1 Chemical Kinetics 1 Purpose: Determine the rate law for the reaction of the dye crystal violet with hydroxide. Reading: Brown, et. al., Chemistry The Central Science, sections 14.1 14.4. Introduction
More informationLab 3: Determination of molar mass by freezing point depression
Chemistry 162 The following write-up may be inaccurate for the particular chemicals or equipment we are using. Be prepared to modify your materials/procedure sections when performing the exercise. Please
More informationExperiment 7. Determining the Rate Law and Activation Energy for the Reaction of Crystal Violet with Hydroxide Ion
Experiment 7. Determining the Rate Law and Activation Energy for the Reaction of Introduction In this experiment, you will observe the reaction between crystal violet and sodium hydroxide. Crystal violet
More informationKinetics of Crystal Violet Bleaching
Kinetics of Crystal Violet Bleaching Authors: V. C. Dew and J. M. McCormick* From Update March 12, 2013 with revisions Nov. 29, 2016 Introduction Chemists are always interested in whether a chemical reaction
More informationDetermining the Concentration of a Solution: Beer s Law
Determining the Concentration of a Solution: Beer s Law The primary objective of this experiment is to determine the concentration of an unknown cobalt (II) chloride solution. You will use a Vernier SpectroVis
More informationDetermining the Concentration of a Solution: Beer s Law
Determining the Concentration of a Solution: Beer s Law Vernier Spectrometer 1 The primary objective of this experiment is to determine the concentration of an unknown copper (II) sulfate solution. You
More informationEXPERIMENT 6 Buffer Effects
EXPERIMENT 6 Buffer Effects Introduction Buffers are solutions that contain an acid and its conjugate base that are designed to resist ph changes. This is important in biological systems to maintain proper
More informationExperiment 11 Beer s Law
Experiment 11 Beer s Law OUTCOMES After completing this experiment, the student should be able to: determine the wavelength (color) of maximum absorbance for a solution. examine the relationship between
More informationExperiment 11 Beer s Law
Experiment 11 Beer s Law OUTCOMES After completing this experiment, the student should be able to: determine the wavelength (color) of maximum absorbance for a solution. examine the relationship between
More informationRate Law Determination of the Crystal Violet Reaction. Evaluation copy
Rate Law Determination of the Crystal Violet Reaction Computer 30 In this experiment, you will observe the reaction between crystal violet and sodium hydroxide. One objective is to study the relationship
More informationExperiment 13. Dilutions and Data Handling in a Spreadsheet rev 1/2013
Absorbance Experiment 13 Dilutions and Data Handling in a Spreadsheet rev 1/2013 GOAL: This lab experiment will provide practice in making dilutions using pipets and introduce basic spreadsheet skills
More informationREVIEW OF LAB TECHNIQUES
Experiment 1 REVIEW OF LAB TECHNIQUES Prepared by Masanobu M. Yamauchi and Ross S. Nord, Eastern Michigan University PURPOSE To review density calculations, Beer s Law and the use of electronic balances,
More informationDETERMINATION OF AN EQUILIBRIUM CONSTANT
DETERMINATION OF AN EQUILIBRIUM CONSTANT In this experiment the equilibrium properties of the reaction between the iron(iii) ion and the thiocyanate ion will be studied. The relevant chemical equation
More informationDetermination of an Equilibrium Constant
Last updated 1/29/2014 - GES Learning Objectives Students will be able to: Determine the numerical value of an equilibrium constant from measured concentrations of all reaction species. Use an absorption
More informationDetermining the Concentration of a Solution: Beer s Law. Evaluation copy. Figure 1
Determining the Concentration of a Solution: Beer s Law Computer 17 The primary objective of this experiment is to determine the concentration of an unknown copper (II) sulfate solution. You will use a
More informationIn fact, we are going to be sneaky and use Hess s Law to determine the heat of magnesium combustion indirectly. Go to the website:
Chemistry 150 Please have the following pages ready before class on Monday, March 3. Write an abstract and paper-clip it to the front of your individual writeup. The abstract and the carbon-copy pages
More informationThe Phase Change Lab: Freezing and Melting of Water
The Phase Change Lab: Freezing and Melting of Water Experiment 3 Freezing temperature is the temperature at which a substance turns from a liquid to a solid. Melting temperature is the temperature at which
More informationRATE LAW DETERMINATION OF CRYSTAL VIOLET HYDROXYLATION
Rate Law Determination of Crystal Violet Hydroxylation Revised 5/22/12 RATE LAW DETERMINATION OF CRYSTAL VIOLET HYDROXYLATION Adapted from "Chemistry with Computers" Vernier Software, Portland OR, 1997
More informationRate law Determination of the Crystal Violet Reaction Using the Isolation Method
Rate law Determination of the Crystal Violet Reaction Using the Isolation Method Introduction A common challenge in chemical kinetics is to determine the rate law for a reaction with multiple reactants.
More informationThe Determination of an Equilibrium Constant
LabQuest 10 The equilibrium state of a chemical reaction can be characterized by quantitatively defining its equilibrium constant, Keq. In this experiment, you will determine the value of Keq for the reaction
More informationLab Investigation 4 - How could you make more of this dye?
Lab Investigation 4 - How could you make more of this dye? USING SPECTROSCOPY TO DETERMINE SOLUTION CON- CENTRATION Guiding Question How could you make more of this dye? INTRODUCTION A solution is a homogeneous
More informationChemical Equilibrium: Finding a Constant, Kc
Lab12 Chemical Equilibrium: Finding a Constant, Kc The purpose of this lab is to experimentally determine the equilibrium constant, K c, for the following chemical reaction: Fe 3+ (aq) + SCN (aq) FeSCN
More informationThe Determination of an Equilibrium Constant
The Determination of an Equilibrium Constant Chemistry 102 10 Chemical reactions occur to reach a state of equilibrium. The equilibrium state can be characterized by quantitatively defining its equilibrium
More informationIntroduction to Spectroscopy: Analysis of Copper Ore
Introduction to Spectroscopy: Analysis of Copper Ore Using a Buret and Volumetric Flask: 2.06 ml of solution delivered 2.47 ml of solution delivered 50.00 ml Volumetric Flask Reading a buret: Burets are
More informationChemical Equilibrium: Finding a Constant, Kc
Chemical Equilibrium: Finding a Constant, Kc Computer 20 The purpose of this lab is to experimentally determine the equilibrium constant, K c, for the following chemical reaction: Fe 3+ (aq) + SCN (aq)
More informationREVIEW OF LAB TECHNIQUES
Experiment 1 REVIEW OF LAB TECHNIQUES Prepared by Masanobu M. Yamauchi and Ross S. Nord, Eastern Michigan University PURPOSE To review density calculations, Beer s Law and the use of electronic balances,
More informationSpectrophotometric Determination of an Equilibrium Constant 1
Spectrophotometric Determination of an Equilibrium Constant 1 Introduction Authors: B. K. Kramer, B. D. Lamp, D. L. McCurdy* and J. M. McCormick from update April 21, 2011 with revisions August 18, 2018
More informationMEASUREMENT: PART II
1 MEASUREMENT: PART II Copyright: Department of Chemistry, University of Idaho, Moscow, ID 83844-2343, 2013. INTRODUCTION Read and/or review Section 1.7 and Figure 7.5 in your textbook. The first part
More informationExperiment 6: Determination of the Equilibrium Constant for Iron Thiocyanate Complex
Experiment 6: Determination of the Equilibrium Constant for Iron Thiocyanate Complex The data for this lab will be taken as a class to get one data set for the entire class. I. Introduction A. The Spectrophotometer
More informationInvestigating Food Dyes in Sports Beverages. Sample
Investigating Food Dyes in Sports Beverages Investigation 1 There are many different brands of beverages that fall under the general category of sports drinks. Most of these beverages contain an FD&C food
More informationSo, What Does it Indicate?
So, What Does it Indicate? Introduction Phenolphthalein is a common indicator you may have used in a previous science course, such as Chemistry 184. In solutions with a ph of less then 8.3, this compound
More informationIntroduction to Spectroscopy: Analysis of Copper Ore
Introduction to Spectroscopy: Analysis of Copper Ore Using a Buret and Volumetric Flask: 2.06 ml of solution 2.47 ml of solution 50.00 ml delivered delivered Volumetric Flask Reading a buret: Burets are
More informationDetermining the Rate Law and Activation Energy for the Methyl Blue Reaction:
Experiment 4 Determining the Rate Law and Activation Energy for the Methyl Blue Reaction: Pre-lab Assignment Before coming to lab: Read the lab thoroughly. An exercise in experimental design Answer the
More informationThe 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 informationIn fact, we are going to be sneaky and use Hess s Law to determine the heat of magnesium combustion indirectly. Go to the website:
Chemistry 161 Please prepare your notebook though the data tables before class on Wednesday, October 27. Write an abstract and place it at the front of your individual report. The abstract and the report
More informationEXPERIMENT 14. ACID DISSOCIATION CONSTANT OF METHYL RED 1
EXPERIMET 14. ACID DISSOCIATIO COSTAT OF METHYL RED 1 The acid dissociation constant, Ka, of a dye is determined using spectrophotometry. Introduction In aqueous solution, methyl red is a zwitterion and
More informationExp 03 - Reaction Rate
GENERAL CHEMISTRY II CAÑADA COLLEGE SUMMER 2018 Exp 03 - Reaction Rate How the speed at which quantities change during a chemical reaction can be measured, predicted and used to understand the mechanism
More informationSo, What Does it Indicate?
So, What Does it Indicate? Introduction Phenolphthalein is a common indicator you may have used in a previous science course, such as Chemistry 130 or Chemistry 170. In solutions with a ph of less then
More informationConcentrations that absorb. Measuring percentage transmittance of solutions at different concentrations
Measuring percentage transmittance of solutions at different Dimension 2 Cross Cutting Concepts Dimension 1 Science and Engineering Practices FRAMEWORK FOR K-12 SCIENCE EDUCATION 2012 Concentrations that
More informationDetermining the Concentration of a Solution: Beer s Law
Determining the Concentration of a Solution: Beer s Law LabQuest 11 The primary objective of this experiment is to determine the concentration of an unknown nickel (II) sulfate solution. You will be using
More informationA Study of Beer s Law Prelab
1. What is the purpose of this experiment? A Study of Beer s Law Prelab 2. Using the absorbance versus wavelength curve given in Figure I, determine the approximate value of max of the dye used to construct
More informationSpectrophotometric Determination of pka of Phenol Red
Spectrophotometric Determination of pka of Phenol Red This experiment uses instrumentation to accomplish quantitative analysis. You will get far more experience in this during CH427 if you are a Chemistry
More informationDetermination of the Equivalent Weight and the K a or K b for a Weak Acid or Base
INTRODUCTION Determination of the Equivalent Weight and the K a or K b for a Weak Acid or Base Chemists frequently make use of the equivalent weight (eq. wt.) as the basis for volumetric calculations.
More informationSize Determination of Gold Nanoparticles using Mie Theory and Extinction Spectra
Size Determination of Gold Nanoparticles using Mie Theory and Extinction Spectra OUTLINE OF THE PROCEDURE A) Measure the extinction spectra of each of your samples. B) Model the extinction spectrum of
More informationChemical Equilibrium: Finding a Constant, Kc
Chemical Equilibrium: Finding a Constant, Kc Experiment 20 The purpose of this lab is to experimentally determine the equilibrium constant, K c, for the following chemical reaction: Fe 3+ (aq) + SCN (aq)
More informationSkill Building Activity 2 Determining the Concentration of a Species using a Vernier Spectrometer
Skill Building Activity 2 Determining the Concentration of a Species using a Vernier Spectrometer Purpose To use spectroscopy to prepare a Beer s Law plot of known dilutions of copper(ii) sulfate so that
More informationAP Chemistry Laboratory #15: Reaction Rate of Crystal Violet and Sodium Hydroxide. Lab days: Thursday and Friday, February 1-2, 2018
AP Chemistry Laboratory #15: Reaction Rate of Crystal Violet and Sodium Hydroxide Lab days: Thursday and Friday, February 1-2, 2018 Lab due: TBD Goal (list in your lab book): The goal of this lab is to
More informationExperiment 7 Buffer Capacity & Buffer Preparation
Chem 1B Dr. White 57 Experiment 7 Buffer Capacity & Buffer Preparation Objectives To learn how to choose a suitable conjugate acid- base pair for making a buffer of a given ph To gain experience in using
More informationExperiment 9. Emission Spectra. measure the emission spectrum of a source of light using the digital spectrometer.
Experiment 9 Emission Spectra 9.1 Objectives By the end of this experiment, you will be able to: measure the emission spectrum of a source of light using the digital spectrometer. find the wavelength of
More informationLinear Motion with Constant Acceleration
Linear Motion 1 Linear Motion with Constant Acceleration Overview: First you will attempt to walk backward with a constant acceleration, monitoring your motion with the ultrasonic motion detector. Then
More information1iI1E. The Determination of 0 an Equilibrium Constant [LU. Computer
Computer The Determination of 0 an Equilibrium Constant Chemical reactions occur to reach a state of equilibrium. The equilibrium state can be characterized by quantitatively defining its equilibrium constant,
More informationSpectrometric Determination of the Acid Dissociation Constant of an Acid-base Indicator
Spectrometric Determination of the Acid Dissociation Constant of an Acid-base Indicator Learning Goals 1. Gain appreciation of the dynamics of perturbing a chemical equilibrium 2. Gain an understanding
More informationDetermination of the Rate of a Reaction, Its Order, and Its Activation Energy
Determination of the Rate of a Reaction, Its Order, and Its Activation Energy Reaction kinetics is defined as the study of the rates of chemical reactions and their mechanisms. Reaction rate is simply
More informationChemical Equilibrium: Finding a Constant, Kc
Chemical Equilibrium: Finding a Constant, Kc Experiment 20 The purpose of this lab is to experimentally determine the equilibrium constant, K c, for the following chemical reaction: Fe 3+ (aq) + SCN -
More informationFinding the Constant K c 4/21/15 Maya Parks Partners: Ben Seufert, Caleb Shumpert. Abstract:
Finding the Constant K c 4/21/15 Maya Parks Partners: Ben Seufert, Caleb Shumpert Abstract: This lab was performed to find the chemical equilibrium constant K c for the reaction Fe 3+ + SCN FeSCN 2+ using
More informationChemical Kinetics: Integrated Rate Laws. ** updated Procedure for Spec 200 use **
Chemical Kinetics: Integrated Rate Laws ** updated Procedure for Spec 200 use ** *DISCLAIMER: It is highly recommended that students bring in their own computers to lab this week to use excel. There may
More informationSpectrophotometry Materials
Spectrophotometry Materials Item per Class per Bench Genesys 10UV Spectrophotometer 6 1 13 ml test tubes box 7 Test tube racks 6 1 1% Albumin solution 25 ml/one flask 2 ml 0.7% Albumin solution (unknown
More informationTHE IRON(III) THIOCYANATE REACTION SYSTEM
Experiment 7 THE IRON(III) THIOCYANATE REACTION SYSTEM Prepared by Ross S. Nord, Chemistry Department, Eastern Michigan University PURPOSE To investigate a novel reaction system by utilizing a spectrophotometer.
More informationExperiment 7A ANALYSIS OF BRASS
Experiment 7A ANALYSIS OF BRASS FV 10/21/10 MATERIALS: Spectronic 20 spectrophotometers, 2 cuvettes, brass sample, 7 M HNO 3, 0.100 M CuSO 4, 2 M NH 3, two 50 ml beakers, 100 ml beaker, two 25 ml volumetric
More informationExperiment 18 - Absorption Spectroscopy and Beer s Law: Analysis of Cu 2+
Experiment 18 - Absorption Spectroscopy and Beer s Law: Analysis of Cu 2+ Many substances absorb light. When light is absorbed, electrons in the ground state are excited to higher energy levels. Colored
More informationCH 112 Special Assignment #4 Chemistry to Dye for: Part C
CH 112 Special Assignment #4 Chemistry to Dye for: Part C PRE-LAB ASSIGNMENT: Make sure that you read this handout and bring the essentials to lab with you. Review Light, energy and color (pp 17-18), Measuring
More informationCHEMISTRY 206 Experiment 4: A KINETIC STUDY
CHEMISTRY 206 Experiment 4: A KINETIC STUDY Instructor s Informal Preamble Chemists are interested in figuring out how reactions happen (i.e., mechanisms), and how quickly they occur (i.e., rates). Both
More informationLab 5 Enthalpy of Solution Formation
Chemistry 3202 Lab 5 Enthalpy of Solution Formation Page 1 of 9 Lab 5 Enthalpy of Solution Formation Introduction This lab activity will introduce you to the measurement of energy change associated with
More informationExercise 2-2. Titration of a Strong Acid EXERCISE OBJECTIVES
Exercise 2-2 Titration of a Strong Acid EXERCISE OBJECTIVES To describe the effect of a ph variation on a chemical indicator; To titrate water containing a strong base solution with a strong acid solution;
More informationKINETICS: INITIAL RATES
Experiment 6B KINETICS: INITIAL RATES Prepared by Ross S. Nord, Stephen E. Schullery, and Masanobu M. Yamauchi, Eastern Michigan University PURPOSE Learn how to measure initial rates. Determine the order
More information2 (aq) [FeSCN [Fe 3JSCN] Figure 1
The Determination of an Equilibrium Constant Computer Chemical reactions occur to reach a state of equilibrium. The equilibrium state can be characterized by quantitatively defining its equilibrium constant,
More information9 Equilibrium. Aubrey High School PreAP -Chemistry. Name Period Date / /
Aubrey High School PreAP -Chemistry 9 Equilibrium Name Period Date / / 9.2 Determination of Keq Lab - Equilibrium Problems Lab Overview In a reversible reaction, equilibrium is the state at which the rates
More informationLab 1: Precision and accuracy in glassware, and the determination of density
Chemistry 140 Please have the following pages ready before class on Monday, October 2. Note that the different parts will be standard divisions in all lab writeups. For this particular writeup, please
More informationpka AND MOLAR MASS OF A WEAK ACID
Experiment 10 pka AND MOLAR MASS OF A WEAK ACID Adapted by the Chemistry Faculty of Eastern Michigan University from EQUL 305,written by Richard C. Bell, Lebanon Valley College, published by Chemical Education
More informationTHE TEMPERATURE DEPENDENCE OF THE EQUILIBRIUM CONSTANT
Experiment 7B THE TEMPERATURE DEPENDENCE OF THE EQUILIBRIUM CONSTANT Prepared by Ross S. Nord, Chemistry Department, Eastern Michigan University PURPOSE To investigate the relationship between the equilibrium
More informationExperiment #7. Determination of an Equilibrium Constant
Experiment #7. Determination of an Equilibrium Constant Introduction It is frequently assumed that reactions go to completion, that all of the reactants are converted into products. Most chemical reactions
More informationSpectrometer User s Guide
Spectrometer User s Guide (Order Codes: V-SPEC, SPRT-VIS, SP-VIS, SP-UV-VIS, ESRT-VIS) The spectrometer is a portable light spectrophotometer, combining a spectrometer and a light source/cuvette holder.
More informationName Date Period. 1. If drops of ACID are added to a ph buffer, then the ph of the buffer will [increase / decrease / stay the same].
Name Date Period ACIDS AND BASES Organisms are often very sensitive to the effect of s and s in their environment. They need to maintain a stable internal ph in order to survive even in the event of environmental
More informationLab #12: Determination of a Chemical Equilibrium Constant
Lab #12: 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 informationAcid-Base Titration Curves Using a ph Meter
Acid-Base Titration Curves Using a ph Meter Introduction: In this experiment you will use a ph sensor to collect volume and ph data as you titrate two acids with sodium hydroxide. You will obtain titration
More informationIntroduction to Spectroscopy: Analysis of Copper Ore
Introduction to Spectroscopy: Analysis of Copper Ore Introduction The goal of this lab is to determine the unknown concentration of two different copper solution samples, taken from fictitious mining sites
More informationIntroduction to Spectroscopy: Analysis of Copper Ore
Introduction to Spectroscopy: Analysis of Copper Ore Thousands of years ago, copper was abundant enough in quantity that it could be found on the Earth s surface. Prospecting for copper then was relatively
More informationExperiment 12H, Parts A and B
Experiment 12H, Parts A and B AHRM 8/17 PRINCIPLES OF EQUILIBRIUM AND THERMODYNAMICS MATERIALS: PURPOSE: 0.0200 M Fe(NO 3 ) 3 in 1 M HNO 3, 0.000200 M KSCN, 2.0 M HNO 3, solid Fe(NO 3 ) 3. 9H 2 O with
More informationExperiment 12: SPECTROSCOPY: EMISSION & ABSORPTION
Sample Experiment 12: SPECTROSCOPY: EMISSION & ABSORPTION Purpose: Emission and absorption spectroscopy is to be explored from different perspectives in a multipart experiment. Part I: Certain elements
More informationDetermination of the K a of a Weak Acid and the K b of a Weak Base from ph Measurements
Experiment 6 Determination of the K a of a Weak Acid and the K b of a Weak Base from ph Measurements Pre-Lab Assignment Before coming to lab: Read the lab thoroughly. Answer the pre-lab questions that
More informationEXPERIMENT #3 A Beer's Law Study
OBJECTVES: EXPERMENT #3 A Beer's Law Study To operate a Spectronic 20 To convert from percent transmission to absorbance units To plot absorbance versus wavelength and find max To plot absorbance versus
More informationJasco V-670 absorption spectrometer
Laser Spectroscopy Labs Jasco V-670 absorption spectrometer Operation instructions 1. Turn ON the power switch on the right side of the spectrophotometer. It takes about 5 minutes for the light source
More informationMORE LIGHTS, COLOR, ABSORPTION!
Name Partner(s) Section Date MORE LIGHTS, COLOR, ABSORPTION! PRE-LAB QUERIES 1. The terms absorption and transmittance are often used when describing the interaction of light with matter. Explain what
More informationIntroduction to Spectroscopy: Analysis of Copper Ore
Absorbance Introduction to Spectroscopy: Analysis of Copper Ore Introduction The goal of this lab is to determine the unknown concentration of two different copper solution samples, taken from fictitious
More informationExperiment 10: TITRATION OF A COLA PRODUCT
Experiment 10: TITRATION OF A COLA PRODUCT Purpose: The mass percent of phosphoric acid in a Cola product is to be determined. Introduction: You might have heard of the claim that Coca-Cola takes the rust
More informationIntroduction to Chemistry Techniques Prelab (Week 1) 2. Determine the number of significant figures in each of the following numbers.
Introduction to Chemistry Techniques Prelab (Week 1) Name Total /10 SHOW ALL WORK NO WORK = NO CREDIT 1. What is the purpose of this experiment? 2. Determine the number of significant figures in each of
More informationSpectroscopy II Introduction: Spectrophotometry and Fluorometry
Introduction: Spectrophotometry and Fluorometry In this experiment you will use the SpectroVis Plus (a small computer controlled Spectrophotometer + Fluorometer) to: Measure the Transmission and Absorbance
More informationEXPERIMENT 6 INTRODUCTION TO SPECTROSCOPY
EXPERIMENT 6 INTRODUCTION TO SPECTROSCOPY INTRODUCTION Much of what we know about the structures of atoms and molecules has been learned through experiments in which photons (electromagnetic radiation
More informationDetermination of an Equilibrium Constant Minneapolis Community and Technical College Principles of Chemistry II, C1152 v.1.16
Determination of an Equilibrium Constant Minneapolis Community and Technical College Principles of Chemistry II, C1152 v.1.16 I. Introduction Equilibrium Consider the following situation: It is rush hour
More informationLaboratory Measurements and Procedures
18 Introduction Measurements of masses, volumes, and preparation of chemical solutions of known composition are essential laboratory skills. The goal of this exercise is to gain familiarity with these
More informationPREPARATION FOR CHEMISTRY LAB: FLUORIDE IN WATER
1 Name: Lab Instructor: PREPARATION FOR CHEMISTRY LAB: FLUORIDE IN WATER On these problems, the solvent is water and the solution is sufficiently dilute so that the density of the solution is the same
More informationAcid-Base Titration. Evaluation copy
Acid-Base Titration Computer 7 A titration is a process used to determine the volume of a solution that is needed to react with a given amount of another substance. In this experiment, your goal is to
More informationChemistry 213. A KINETIC STUDY: REACTION OF CRYSTAL VIOLET WITH NaOH LEARNING OBJECTIVES
Chemistry 213 A KINETIC STUDY: REACTION OF CRYSTAL VIOLET WITH NaOH The objectives of this experiment are to... LEARNING OBJECTIVES study the reaction rate of crystal violet with NaOH using a Spectronic
More informationAP CHEMISTRY LAB RATES OF CHEMICAL REACTIONS (II)
PURPOSE: Observe a redox reaction. AP CHEMISTRY LAB RATES OF CHEMICAL REACTIONS (II) Apply graphing techniques to analyze data. Practice computer skills to develop a data table. Determine the order of
More informationChemistry 112 Laboratory Experiment 7: Determination of Reaction Stoichiometry and Chemical Equilibrium
Chemistry 112 Laboratory Experiment 7: Determination of Reaction Stoichiometry and Chemical Equilibrium Introduction The word equilibrium suggests balance or stability. The fact that a chemical reaction
More informationExercise 5: The electromagnetic spectrum and spectroscopy
Physics 223 Name: Exercise 5: The electromagnetic spectrum and spectroscopy Objectives: Experience an example of a discovery exercise Predict and confirm the relationship between measured quantities Using
More information