Experiment 1: Find the Calorimeter Constant
Take a constant temperature bath from the Instruments shelf and place it on the workbench.
Run the bath at 60 °C.
Take an Erlenmeyer flask from the Containers shelf and place it on the workbench.
Take water from the Materials shelf and add 50.0 mL to the flask.
Place the flask into the constant temperature bath.
Take a thermometer from the Instruments shelf and attach it to the flask.
Take a calorimeter from the Containers shelf and place it on the workbench.
Take water from the Materials shelf and add 50.0 mL to the calorimeter.
Take a thermometer from the Instruments and attach it to the calorimeter. Record the temperature in your Lab Notes. (TEMP was 21.5 Celsius)
When the temperature of the water in the Erlenmeyer flask reaches 60 °C, remove the thermometer from the flask and drag and drop the flask onto the calorimeter. Select Pour All to empty the flask into the calorimeter.
Record the temperature of the combined liquid in the calorimeter in your Lab Notes. (Temp. was 39.6 Celsius)
Clear your station by dragging all containers and instruments to the recycling bin beneath the workbench.
Experiment #1 Questions
1) How much heat was lost by the hot water?
2) How much heat was absorbed by the cold water?
3) How much heat was absorbed by the calorimeter?
4) What was the Delta T for the cold water?
5) What was the Delta T for the hot water?
6) The value of the calorimeter constant is between ?
Experiment 2: Determine the Enthalpy of Neutralization of HCl by NH3
Take a new calorimeter from the Containers shelf and place it on the workbench.
Take 2 M hydrochloric acid (HCl) solution from the Materials shelf and add 25.0 mL to the calorimeter.
Take a thermometer from the Instruments shelf and attach it to the calorimeter. Record the temperature inside the calorimeter in your Lab Notes. (Temp was 21.5 Celsius)
Take 2 M ammonia (NH3) solution from the Materials shelf and add 25.0 mL to the calorimeter. Observe the temperature change in the calorimeter and record it in your Lab Notes. (TEMP was 33.2 Celsius) Make sure to record the highest temperature before the calorimeter begins to lose heat to the surroundings.
Clear your station by dragging all containers and instruments to the recycling bin. Remember to press Save Notes.
Experiment #2: Questions.
1) What is the heat solution (qsoln) for the neutralization reaction between NH3 and HCI?
2) What is the heat of the reaction for the neutralization reaction between NH3 and HCI?
Experiment 3: Determine the Enthalpy of Dissolution of NH4Cl in Water
Take a new calorimeter from the Containers shelf and place it on the workbench.
Take water from the Materials shelf and add 25.0 mL to the calorimeter.
Take a thermometer from the Instruments shelf and attach it to the calorimeter. Record the temperature inside the calorimeter in your
Lab Notes. (TEMP was 21.5 Celsius)
Take ammonium chloride (NH4Cl) from the Materials shelf and add 5.000 g to the calorimeter.
Observe the temperature change in the calorimeter as the reaction proceeds. Record the new temperature your Lab Notes. (TEMP was 9.1 Celsius)
Clear your station by dragging all containers and instruments to the recycling bin. Remember to press Save Notes.
Experiment #3 Questions:
1) What was the heat of solution (qsoln) for the dissolution of ammonium chloride in water?
2)What was the value for cal for the dissolution of ammonium chloride in water?
3)Based on the molar enthalpies calculated for experiment 2 and 3, use Hess's law to write a series of reactions that will sum up to the reaction of the decomposition of ammonium chloride. In addition to the molar enthalpies for experiment 2 and 3, you will also need to include the following reactions which account for the enthalpy change when HCI and NH3 change state:
NH3(g) -> NH3(aq) (deltaH = -34,640 J/mol) HCl(g) -> HCl(aq) (deltaH = -75,140 J/mol)Choose the equation that shows the correct direction and sign for the enthalpy value for the reaction between NH3 and HCI in your series of reactions.
1) HCI(aq)+NH3(aq) --> NH4CI(s) -delta H
2) HCI(g)+NH3(g) --> NH4CI(aq) +delta H
3) NH4CI(s)-->HCI(g)+NH3(aq) -delta H
4) NH4CI(aq)-->HCI(aq)+NH3(aq) +delta H