Chemistry 1 Lab Report

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Experiment 12: Calorimetry and Hess’s Law

The purpose of this lab is to determine the enthalpy of reaction for the burning of one mole of magnesium in oxygen. Although the reaction is exothermic, the ∆HRXN will be determined by using calorimetry and then using Hess’s Law to manipulate the data collected to yield the answer needed.

Dillon, Stephanie. “ Calorimetry and Hess’s Law.” Laboratory Manual. Pearson Publishing, 2012, pp.168-177.

Data and Results
Part A
Volume of cold water| 49.9 mL|
Temperature of cold water (in cup)| 23.50 C|
Volume of hot water| 49.9 mL|
Temperature of hot water(in cup)| 550 C|
Part A Calculations
Mass of cold water| 49.9 g|
Tf from graph by extrapolation| 34.90 C|
∆THW for hot water| -20.1|
∆TCW for cold water| 11.4|
qHW for hot water| -4196.5 J|
qcw for cold water| 2380.1 J|
qCal for the cup| 1816.4 J|
Ccup for the cup| 159.3 J|

Part B
Description of sample| Metal fizzed when dissolved in HCl| Volume of HCl| 100 mL|
Initial Temperature| 220 C|
Mass of Mg| 0.1485 g|
Part B Calculations
Tf from graph| 50 C|
Mass of HCl| 100 g|
∆TCW for HCl| -2092 J|
qHCl for solution| -204.4 J|
qCal for cup| -2296.4 J|
qRXN | -47594 J|
∆HRXN for Mg| |
NET REACTION: 2HCl(aq) + Mg(s)→MgCl2(aq) + H2(g)
Part C
Description of sample| |
Volume of HCl| 100 mL|
Temperature of HCl| 220 C|
Mass of MgO| 0.5052 g|

Part C Calculations
Tf from graph| 240 C|
∆TCW for HCl| 1.50 C|
qHCl for HCl| 627.6 J|
qCal for cup| 61.32 J|
qRXN| 608.92 J|
∆HRXN for Mgo| 55469 J/mol|

Net Equation: 2HCl(aq) + MgO(s)→MgCl2(aq) + H2O(l)


Conclusion: In this experiment we had to find the heat capacity of the calorimeter cup using two trials of hot and cold water. When we obtained the data after 10 minutes of recording 30 second intervals of the calorimeter cup temperature, we created...
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