What sort of relationship exists between the temperature change and the mass of the salt dissolved? Explain your answer.
The Fundamentals of Calorimetry
- Experimental Data
Insert graph of the data from Data Table 1, plotting temperature vs. time, and use the Y intercept to find the temperature at time 0 when the two volumes of water are mixed.
|Trial 1 (include units)||Trial 2 (include units)||Calculations (for Trial 1)|
|Initial temperature of cold water|
|Initial temperature of warm water|
|Temperature at time 0 from graph, T0|
|Heat lost by hot water|
|Heat gained by cold water|
|Heat gained by calorimeter|
|Temperature change of calorimeter|
|Heat capacity of calorimeter|
|Average Heat capacity of calorimeter|
Report data with correct units. Show calculations below the table
|Mass of water
|Mass of salt
|Moles of salt
|Change in Temperature|
|Heat released/absorbed by water|
|Heat released/absorbed by the calorimeter|
|Enthalpy of solution
|Molar Enthalpy of solution|
|Average molar enthalpy of solution|
Show calculations for first column:
- Moles of salt
- Heat released/absorbed by the solution
- Heat released/absorbed by the calorimeter
- Enthalpy of solution (J)
- Enthalpy of solution (kJ)
- Molar Enthalpy of solution
- Average molar enthalpy of solution
Insert graphs of ΔT vs. grams of salt for NH4Cl
- What sort of relationship exists between the temperature change and the mass of the salt dissolved? Explain your answer.
- The actual molar enthalpy of solution for calcium chloride is -81.3 kJ/mol, whereas the molar enthalpy of solution of ammonium chloride is 14.8 kJ/mol. Calculate the percent error of your results. Show the calculations.
- Use the value of enthalpy you determined for CaCl2 to calculate what quantity of salt will be needed to make a chemical hot pack. Assume using 100 g (100 mL) of water and changing the temperature from 25 °C to 60 °C. Show all calculations.
- Use the graph you drew for NH4Cl to determine the amount of salt needed to make a chemical cold pack. Assume using 100 g (100 mL) of water. The temperature should go down to 3.0 °C from a room temperature of 25 °C. Show all calculations.
- Suggest practical ways in which the calorimeter or lab protocol could be improved to decrease percent errors.