Hess Law Lab

Purpose

Measure the enthalpy for three reactions and to confirm the value of Hess legality in predicting the ?H of a reaction

A) NaOH(s) NaOH(aq)
B) NaOH(aq) + HCl(aq) NaCl(aq) + H2(l)
C) NaOH(s) + HCl(aq) NaCl(aq) + body of water(l)

Materials

Styrofoam Cup Calorimeter| Forceps|
Thermometer| NaOH Pellets|
Graduated cylinder| 0.50M HCL|
Beaker| Magnetic Stirrer|
Stirring Hot Plate| |
| |

Procedure

Thermometers were apply instead of Lob pro. (Refer to lab handout)

Observations

Table One: Results for plane section A:
Trial| fold m / g| Temperature of H2O (±0.1°C)|
| Cups| Cups, H2O, Pellets| Cups, Pellets | sign Ti / °C| Final Tf / °C| change ?T / °C|
1| 7.14g| 56.15g| 8.15g| 19.3°C| 23.0°C| 3.7°C|
2| 7.49g| 55.17g| 8.48g| 19.4°C| 23.5°C| 4.1°C|
3| 8.02g| 54.15g| 9.03g| 19.4°C| 23.2°C| 3.8°C|

Table Two: Results for Part B:
Trial| Mass m / g| Temperature of H2O (±0.05°C)| Temperature of HCl (±0.1°C)|
| Cups, H2O, Pellets| Initial Ti / °C| Final Tf / °C| Final Tf / °C|
1| 104.66g| 21.2°C| 21.1°C| 24.9°C|
2| 103.40g| 20.2°C| 22.3°C| 24.6°C|
3| 102.56g| 20.0°C| 22.1°C| 24.



7°C|

Table Three: Results for Part C:
Trial| Mass m / g| Temperature of H2O and HCl (±0.1°C)|
| Cups| Cups, H2O, Pellets| Cups, H2O, Pellets| Initial Ti / °C| Final Tf / °C| Change ?T / °C|
1| 7.41g| 104.41g| 8.41g| 20.4°C| 23.9°C| 3.5°C|
2| 7.85g| 103.12g| 8.84g| 20.1°C| 25.0°C| 4.9°C|
3| 8.33g| 103.01g| 7.61g| 20.2°C| 24.2°C| 4.0°C|

Analysis

ingest Calculations: Trial One: Part A
* ?H=mH2OcH2O?tnNaOH
* ?H=48.00g4.18Jg-1K-13.7K0.025mol
* ?H=29694.72Jmol-1=29.69kJmol-1

Sample Calculation: Trial One: Part A: flaw
* Error=mH2OcH2O?tnNaOH
* Error=0.010.20.01
* Error=21%+5.4%+40%=66.4%
* Error=19.72kJmol-1

Trial| Enthalpy ?H / kJmol-1|
Trial One|...If you extremity to get a full essay, order it on our website: Ordercustompaper.com



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