Essay on Lab 4 formal report

Submitted By jvleeson
Words: 1944
Pages: 8
Open Document
Introduction/Purpose
In all reactions, elements or compounds undergo changes in internal energy. One component that has a major effect on the changes in internal energy is the transfer of heat. Calorimetry is the study of the changes in heat that accompany all chemical reactions. Calorimetric experiments are always done under controlled, specific conditions. In this case, the experiments will be done using an expanded polystyrene calorimeter to measure the heat of dissolution of NaOH as well as its concentration (using the heat of a neutralization reaction between NaOH and HCl). However, this can only be done accurately if the heat capacity of the calorimeter is determined, that is, the amount of energy needed to raise its temperature by 1°C (or K). In order to do this, a known mass of cold water will be added to a known mass of hot water in the calorimeter. As heat is lost by the calorimeter and by the hot water while begin absorbed by the cold water, the following equation can be used to determine the calorimeter’s heat capacity: . The calorimeter used is not a sealed system. Consequently, the reactions occur at constant pressure, and the heat of reactions are equal to the enthalpy change of the reaction, ΔH. To calculate the heat of dissociation per mole of NaOH (assuming heat is lost to the calorimeter), the following equation will be used:
. However, if it is assumed that no heat is lost to the calorimeter, qcal can be ignored in the equation. This equation is valid because it is assumed that no heat in the system is lost to the surroundings, and thus, qrxn + qcal + qsoln = 0. A similar equation can be used to determine the concentration of NaOH in a solution. Since it is known that ΔH = -55.90kJ/molH2O for all neutralization reactions involving strong electrolytes (because the heat of reaction essentially results from the formation of water from hydrogen ions and hydroxide ions), the concentration of NaOH in the solution can be calculated as follows: [. To calculate ΔHrxn, qcal may or may not be accounted for. The effectiveness of these methods can be determined by comparing them to the results obtained by using the mass of NaOH used and the volume of the solution.
Experimental Procedure
“The experimental procedure used for this experiment was outlined in the CHEM 120L manual, Experiment #4. All steps were followed without deviation.”
Experimental Observations
Part A
T(i) water = 23.0°C
Temperature of solution (every 10sec for 1min) (°C)
Temperature of solution (every min for 24min) (°C)

Mass (NaOH) used = 10.23g
(1) 24.0
(1) 33.0
(7) 35.5
(13) 34.25
(19) 33.0
Mass cal. = 48.25g
(2) 25.0
(2) 34.0
(8) 35.5
(14) 34.0
(20) 33.0

(3) 26.0
(3) 35.0
(9) 35.5
(15) 34.0
(21) 32.75

(4) 27.0
(4) 35.0
(10) 35.25
(16) 33.75
(22) 32.5

(5) 30.0
(5) 35.5
(11) 35.0
(17) 33.5
(23) 32.25

(6) 31.0
(6) 35.5
(12) 34.5
(18) 33.0
(24) 32.25

Part B
Mass of calorimeter with 125mL of heated DI water = 146.85g
Mass of calorimeter with 125mL DI water (after reaction is complete) = 269.65g
Initial temperature of cool water = 24.0°C
Temperature of mixture IMMIDIATLY after mixing = 33.2°C

Temp. of heated water at 5 1min intervals prior to mixing (°C)
Temp. of heated mixture at 1min intervals for 10min (°C)

(1) 44.75
(1) 33.0
(6) 32.0
(2) 43.5
(2) 32.0
(7) 32.0
(3) 43.0
(3) 32.0
(8) 32.0
(4) 43.0
(4) 32.0
(9) 32.0
(5) 42.0
(5) 32.0
(10) 32.0

Part C
Concentration of HCl from carboy = 1.167M
Temp. of HCl before mixing = 25.0°C
Temp. of NaOH before mixing = 25.0°C

Temperature after mixing at 5 second intervals for 1 minute (°C)

Temperature after mixing at 30 second intervals for 9 additional minutes (°C)

(1) 29.0
(7) 28.90
(1) 28.90
(7) 28.75
(13) 28.6
(2) 29.0
(8) 28.90
(2) 28.90
(8) 28.75
(14) 28.6
(3) 29.0
(9) 28.90
(3) 28.90
(9) 28.75
(15) 28.6
(4) 29.0
(10) 28.90
(4) 28.90
(10) 28.75
(16) 28.6
(5) 29.0
(11) 28.90
(5) 28.75
(11) 28.75
(17) 28.5
(6) 29.0
(12) 28.90
(6) 28.75
(12) 28.6
(18) 28.5

Results & Calculations
Part A –
Show More

Related Documents: Essay on Lab 4 formal report

Osmosis: Experiment and Lab Essay examples

of reporting your results. Formal Lab Reports: You should keep ALL COMPLETE copies of lab reports in your 3-ring binder in a back section/tab labeled “AP Lab Reports”. Ultimately, all formal labs and lab worksheets should go into this binder for later use during review. Formal lab reports will be done on the computer and NEED TO BE TYPED and submitted to www.turnitin.com! They should be stored on a hard-drive or on disc/cd/flashdrive for back-up. Formal lab write-ups should contain the following:…

Words 5942 - Pages 24

Laboratory Techniques and Measurements Essay

Peter Jeschofnig, Ph.D. Version 42-0165-00-01 Lab RepoRt assistant This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file…

Words 949 - Pages 4

Essay on Scientific Method and Data Points

Name ________________________________________________ Ms. Lin Science Formal Lab Rubric Lab Report Title ________________________________________ Period _______ Criteria | Evidence | Evaluation | | | 4 | 3 | 2 | 1 | Purpose & Question/Hypothesis | The question to be investigated is clearly identified, well stated and seems likely to be answerable via scientific…

Words 368 - Pages 2

Density Lab Outline Essay

writing a lab report is to provide a blueprint for another scientist to repeat your experiment and get the same results. A COPY OF THIS DOCUMENT incl. the finished PRE-LAB SECTIONis due on FORMAL LAB DAY! Written work should never be copied from other groups. Use your own words! Read skills section in back of text. Make sure you are familiar with using a graduated cylinder and an electronic balance and how to write a lab report (see class website) and how to draw and label diagrams. Required Lab sections-headings…

Words 2481 - Pages 10

Synthesis Of Geometric Isomers

Experiment 1 Synthesis of Geometric Isomers Techniques to review before coming to the laboratory: Appendix C: Vacuum filtration, Refluxing Type of Lab Report: Modified Formal, review Appendix A: Modified Formal Lab Reports, hand in at the beginning of your next lab. Introduction: Alkenes are hydrocarbons with a C=C double bond. The double bond is stronger than a single bond, yet paradoxically, the C=C double bond is much more reactive than a C-C single bond. Historically, hydrocarbons…

Words 1976 - Pages 8

Overview: Human Anatomy and Lab Report Assistant Essay

Anatomy Laszlo Vass, Ed.D. Version 42-0001-00-01 Lab Report Assistant This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable…

Words 1180 - Pages 5

Essay on A and P

Histology Laszlo Vass, Ed.D. Version 42-0013-00-01 Lab RepoRt assistant This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file…

Words 1206 - Pages 5

Essay on Electric Charge and Lab Report Assistant

Jeschofnig, Ph.D. Version 42-0278-00-01 Lab Report Assistant This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable…

Words 1262 - Pages 6

Essay on Histology Lab

Histology Laszlo Vass, Ed.D. Version 42-0013-00-01 Lab RepoRt assistant This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file…

Words 1351 - Pages 6

A Guide For A Guide To The Purdue University

with your writing assignments or for general writing support: • Visit the OSU Writing Center. Call 688-6429 to make an appointment, drop by, or visit their website at: http://cstw.osu.edu/writingcenter • Visit the Purdue University online writing lab (OWL) at: http://owl.english.purdue.edu/owl/ • Visit the following site for APA citation format: http://owl.english.purdue.edu/owl/section/2/10/ TABLE OF C ON TE N TS I. Introduction ..........................................................…

Words 7376 - Pages 30