1. Outline how you would use a calorimeter to determine the enthalpy of fusion of ice.

2. Suppose the enthalpy of fusion of ice determined from your experiment is lower than the accepted value. List three possible causes of the difference in value. Explain how each cause affects the calculated value of Hf.

1. To determine the enthalpy of fusion of ice using a calorimeter, you would follow these steps:

Step 1: Set up the calorimeter: Use a double-walled container with an insulated lid, preferably made of a material with high thermal conductivity like metal. Fill the inner chamber with a known volume of water.

Step 2: Measure the initial temperature: Record the initial temperature of the water inside the calorimeter.

Step 3: Prepare the ice: Obtain a known mass of ice and allow it to melt slightly until it reaches a slushy consistency.

Step 4: Add the ice to the calorimeter: Transfer the slushy ice into the calorimeter while carefully avoiding any water spills. Stir the mixture gently to ensure the ice is evenly distributed.

Step 5: Measure the final temperature: Monitor the temperature until a steady-state is reached, and record the final temperature.

Step 6: Calculate the heat gained by water: Determine the heat gained by the water in the calorimeter using the formula Q = m * c * ΔT, where Q is the heat gained, m is the mass of water, c is the specific heat capacity of water, and ΔT is the temperature change (final minus initial).

Step 7: Calculate the enthalpy of fusion: Use the equation ΔHf = Q / n, where ΔHf is the enthalpy of fusion, Q is the calculated heat gained by the water, and n is the number of moles of water.

2. If the enthalpy of fusion of ice determined from the experiment is lower than the accepted value, there could be several causes for the difference:

a. Heat loss to the surroundings: If there was insufficient insulation of the calorimeter, heat could escape to the surrounding environment, resulting in a lower measured temperature change. This would lead to a lower calculated enthalpy of fusion value since less heat was recorded.

b. Incomplete thermal equilibrium: It is crucial to ensure that a steady-state is reached, meaning that the whole system, including the water and ice mixture, has reached thermal equilibrium. If the system is not given enough time to stabilize, the final temperature measurement may be lower than it should be, resulting in a lower calculated enthalpy of fusion value.

c. Experimental errors: Mistakes in measurements, such as inaccurate weighing of ice or water, imprecise temperature readings, or incorrect calibration of the calorimeter, can all contribute to errors in the calculated enthalpy of fusion value. These errors can accumulate and result in an underestimated enthalpy of fusion.

In summary, the lower measured value of enthalpy of fusion could be due to heat loss to the surroundings, incomplete thermal equilibrium, and experimental errors in the measurements. Each of these causes affects the calculated value of enthalpy of fusion by introducing inaccuracies and reducing the recorded heat absorbed by the water in the calorimeter.