etermine the change in temperature of the system after dissolution of the various salts in water. 2. Determine the heat of dissolution/energy change (Q, in joules) for each one of the solutions prepared. (Q of water is 4.18 J/goC) 3. Calculate the heat of dissolution per mole of solute (Qsoln, in kJ/mol) for each one of the ionic solids used. 4. Based on these results, describe the energy changes that take place when each one of the salts dissolves in water. Which ionic solid has an exothermic heat of dissolution in water (releases
Data Table –– Heat of Dissolution |
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Salt |
NH4Cl |
CaCl2 |
NaCl |
NaOH |
Volume of water |
45.0 mL |
45.0 mL |
45.0 mL |
45.0 mL |
Density of H2O |
0.9989 g/mL |
0.9989 g/mL |
0.9989 g/mL |
0.9989 g/mL |
Mass of H2O |
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Mass of salt |
5.005 g |
5.037 g |
5.024 g |
5.078 g |
Molar mass of salt |
53.49 g/mol |
110.98 g/mol |
58.44 g/mol |
40.00 g/mol |
Moles of salt |
0.009357 mol |
0.04539 mol |
0.08597 mol |
0.1269 mol |
Mass of solution (m) |
50.0 g |
50.1 g |
50.1 g |
50.1 g |
Initial temperature (Tinitial) |
23.9°C |
22.2°C |
23.7°C |
22.8°C |
Final temperature (Tfinal) |
16.5°C |
36.5°C |
21.5°C |
40.5°C |
Temperature change (Tfinal−Tinitial) |
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Heat of dissolution (Q) |
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Heat of dissolution per mole (Qsoln) |
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Fill out the missing rows of your data table.
(for numbers 1-3, you can pick one column of solid and just show the calculation for that column)
- Determine the change in temperature of the system after dissolution of the various salts in water.
2. Determine the heat of dissolution/energy change (Q, in joules) for each one of the solutions prepared. (Q of water is 4.18 J/goC)
3. Calculate the heat of dissolution per mole of solute (Qsoln, in kJ/mol) for each one of the ionic solids used.
4. Based on these results, describe the energy changes that take place when each one of the salts dissolves in water. Which ionic solid has an exothermic heat of dissolution in water (releases heat to surroundings)? Which ionic solid has an endothermic heat of dissolution in water (absorbs heat from the surroundings)? Which solid will make the best cold pack and why?
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