CHEM101 Lab: Experiment 8 - Heat Capacity and Enthalpy Changes

This document is a student's lab report detailing Experiment 8, which focuses on calorimetric measurements and thermochemical calculations. The report includes calculations for the heat capacity of a calorimeter, the enthalpy of neutralization of HCl and NaOH, and the heat of solution of NaOH. The student performed experiments, recorded data, and computed the heat changes (q) for each process, as well as the enthalpy changes (ΔH) per mole of water formed or NaOH reacted. The report includes a summary table comparing the experimental and theoretical molar enthalpies for the reactions. Calculations involve the use of the formula: q = m x c x ΔT, where m is the mass, c is the specific heat capacity, and ΔT is the change in temperature. The final results are presented in kJ/mol.

NAME:
EXPERIMENT 8: PARTNER:
DATE:
REPORT SHEET
1. HEAT CAPACITY OF CALORIMETER
Calculations
Temperature of cold water 6.5 oC
Temperature of warm water 42.9 oC
Maximum temperature reached 33.5 oC
T (cold water)* 33.5-6.5 27oC
T (hot water)* 33.5-42.9 -9.4°C
Heat lost by warm water Mass x change in temperature
x specific heat capacity of
water
=(50ml)x(1g/cm3)x4.184x-9.4
-1966.48J
Heat gained by cold water Mass x change in temperature
x specific heat capacity of
water
=(50ml)x(1g/cm3)x4.184x27
5648.4J
Heat gained by calorimeter q(warm)+q(cold)
+q(calorimeter)=0
q(calorimeter)=0-(5648.4-
1966.48)
-3681.92J
Heat capacity of calorimeter Heat gained by the
calorimeter/change in
calorimeter temperature -136.37
j/°c

=-3681.92/27
* Remember, T = final temperature – initial temperature

2. NEUTRALIZATION OF HCl (aq) AND NaOH (aq)
Calculations
Initial temperature NaOH 21.2 oC
Final temperature of mixture 27.7 oC
Change in temperature 27.7-21.2 6.5 oC
qsolution Mass x change in
temperature x specific heat
capacity of water
=100mlx1.02g/
mlx6.5°cx4.02joule/gram/°c
2665.26J
qcalorimeter Change in temperature x
heat capacity of calorimeter
=6.5x-136.37
-886.405J
qreaction qsolution + qcalorimeter + qreaction=0
qreaction =0-(2665.26+-
886.405)
-1778.86J
Enthalpy of Neutralization
(per mole water formed)
-1778.86/0.05moles
=-35577.1j/mol
Then divide by 1000 to
convert to kilojoules
-35.58kJ/mol
3. HEAT OF SOLUTION OF NaOH(s)
Calculations
Mass of NaOH used 2.20 g
Initial temperature water 18.9 oC
Highest temperature reached 28.5 oC
Change in temperature 28.5-18.9 9.6 oC
qsolution Mass x change in
temperature x specific heat

capacity of water
=100ml x 1.02g/ml x9.6°c x
4.02joules/gram/°c
3936.38J
qcalorimeter Change in temperature x
heat capacity of calorimeter
=9.6x-136.37
-1309.15J
qreaction qsolution + qcalorimeter + qreaction=0
qreaction =0-(3936.38+-
1309.15)
-2627.23J
Enthalpy of Solution
(per mole NaOH)
-2627.23/0.05moles
=-52544.6 j/mol
Then divide by 1000 to
convert to kilojoule
And dividing by 1000 to
change to kilojoules
-52.54kJ/mol

4. HEAT OF REACTION OF HCl(aq) AND NaOH(s)
Method of Calculation
Mass of NaOH used 2.20 g
Initial temperature HCl 21.4 oC
Highest temperature reached 33.5 oC
Change in temperature 33.5-21.4 12.1 oC
qsolution Mass x change in
temperature x specific heat
capacity of water
=100ml x 1.02g/ml x12.1°c
x4.02gj/g/°c
4961.48J
qcalorimeter change in temperature x heat
capacity of calorimeter
=12.1x-136.37
-1650.08J
qreaction qsolution + qcalorimeter + qreaction=0
qreaction =0-(4961.48 + -
1650.08)
-3311.40J
Enthalpy of Neutralization
(per mole NaOH reacted)
3311.40/0.05moles
=-66228.061j/mol
Then divide by 1000 to
convert to kilojoule
-66.23kJ/mol
5. SUMMARY REPORT:
Experimental Theoretical
Molar Enthalpy (Part 2) (kJ) -35.58 -56.7
Molar Enthalpy (Part 3) (kJ) -52.54 -44.2
Sum (Part 2 + Part 3) (kJ) -88.12 -100.9
Molar Enthalpy (Part 4) (kJ) -66.23 -58