Latent Heat of Fusion Lab Manual

1. Title: Latent Heat of Fusion Lab

2. Objective:

• Determine the latent heat of fusion of ice.
• Understand the concept of phase changes and latent heat.
• Apply calorimetry principles to measure heat transfer.
• Analyze the energy involved in melting a solid substance.

3. Introduction:

The latent heat of fusion (Lf) is the amount of heat energy required to change a substance from a solid to a liquid at its melting point, without changing its temperature. This heat energy is used to overcome the intermolecular forces holding the solid together, allowing it to transition to the liquid phase.

The amount of heat (Q) required to melt a mass (m) of a substance at its melting point is given by:

Q = m * Lf

where:

• Q is the heat energy
• m is the mass of the substance
• Lf is the latent heat of fusion

In this lab, you will use calorimetry to determine the latent heat of fusion of ice by measuring the heat transfer when ice melts in water.

4. Materials:

• Calorimeter (e.g., Styrofoam cup with lid)
• Thermometer
• Triple beam balance
• Beaker
• Ice
• Water

5. Procedure:

1. Setting up the Calorimeter:

1. Weigh the empty calorimeter cup and record the mass (mc) in a table.
2. Add a known mass of water to the calorimeter cup and record the mass (mw) in a table.
3. Measure the initial temperature of the water (Tw) using a thermometer. Record the initial temperature in a table.

2. Adding Ice to the Calorimeter:

1. Weigh a small amount of ice and record the mass (mi) in a table.
2. Carefully add the ice to the calorimeter cup containing the water.
3. Close the lid of the calorimeter and gently stir the mixture until all the ice has melted.
4. Measure the final temperature of the water (Tf) using a thermometer. Record the final temperature in a table.

6. Data Analysis:

Calculate the heat lost by the water (Qw) as it cools down. Calculate the heat gained by the ice (Qi) as it melts and warms up to the final temperature. Apply the principle of calorimetry (Qw + Qi = 0) to determine the latent heat of fusion of ice (Lf). Estimate the uncertainties in your measurements and propagate them to calculate the uncertainties in your Lf value. Compare your result with the accepted value of Lf (3.34 x 10^5 J/kg) and discuss any discrepancies.

7. Discussion:

1. How does the heat lost by the water compare to the heat gained by the ice?
2. What are the sources of error in your measurements? How could these errors be minimized?
3. How does the heat capacity of the calorimeter affect your results?
4. How does the initial temperature of the ice affect your results?
5. How well does your experimental result for Lf agree with the accepted value?
6. What are some practical applications of latent heat of fusion?

8. Conclusion:

In this lab, you have determined the latent heat of fusion of ice using calorimetry. You have also learned how to apply the principle of calorimetry to measure heat transfer and analyze the energy involved in melting a solid substance. By understanding the concept of latent heat of fusion, you have gained a deeper understanding of the principles of thermodynamics and phase changes.