10. How Can We Show Heat of Fusion and Heat of Vaporization in a University Lab Experiment?

Welcome to the exciting world of thermodynamics! Here, we will discover some cool something important about how matter changes from one form to another. Today, we will look at Heat of Fusion and Heat of Vaporization. Are you ready for this science adventure? Let’s get started!

Experiment Overview

We can do two simple experiments to show heat of fusion and heat of vaporization: Melting Ice to learn about heat of fusion, and Boiling Water to explore heat of vaporization. We will use easy-to-find materials, making the experiments fun and straightforward for college students!

Experiment 1: Demonstrating Heat of Fusion

Objective: Measure the heat absorbed by ice as it melts into water.

Materials Needed:

• A calorimeter (or a similar insulated container)
• Ice (crushed ice works best)
• Thermometer
• Hot water
• Scale to measure weight

Procedure:

1. Get your calorimeter ready: Put a known amount of ice in it. Use the scale to measure how much ice you have. We'll call this amount $m_{ice}$.
2. Check the ice temperature: Use the thermometer to measure the starting temperature of the ice. It should be around 0°C.
3. Add warm water: Pour a set amount of warm water (about 50°C) into the calorimeter. Measure this amount and call it $m_{water}$.
4. Stir gently: After a few minutes, stir the mixture gently to ensure everything mixes well, and watch the thermometer.
5. Record final temperature: When all the ice has melted, write down the final temperature, called $T_f$.

Data Analysis:

Using the energy conservation principle, the heat absorbed by the ice ($Q_{ice}$) should equal the heat lost by the warm water ($Q_{water}$). We can calculate the heat the ice absorbed using:

$Q_{ice} = m_{ice} \cdot L_f$

Here, $L_f$ is the heat of fusion of ice (about 334 J/g). The heat lost by the water can be calculated with:

$Q_{water} = m_{water} \cdot c_{water} \cdot (T_{initial} - T_f)$

In this case, $c_{water}$ is the specific heat of water (about 4.18 J/g°C). Set $Q_{ice} = Q_{water}$, and solve for $L_f$!

Experiment 2: Demonstrating Heat of Vaporization

Objective: Measure the heat needed to turn water into steam.

Materials Needed:

• Calorimeter or beaker
• Heat source (like a hot plate)
• Water
• Thermometer
• Scale to measure weight

Procedure:

1. Fill the calorimeter: Pour a known amount of water ($m_{water}$) into the calorimeter.
2. Measure initial temperature: Check the starting temperature $T_i$, which should be around room temperature.
3. Heat the water: Place the calorimeter on the hot plate and heat the water until it begins to boil. Keep measuring the temperature as it heats up.
4. Record the boiling point: When the water starts to boil and turns into steam, measure how long it takes for a set amount of water (like 100 g) to completely evaporate.
5. Collect vapor: If you can, catch the steam and measure what’s left of the water.

Data Analysis:

To find the heat needed to vaporize the water, use:

$Q_{vaporization} = m_{vaporized} \cdot L_v$

Where $L_v$ is the heat of vaporization of water (about 2260 J/g). We can also use energy conservation:

$Q_{heat} = m_{water} \cdot c_{water} \cdot (T_{boiling} - T_i)$

This fun exploration gives you hands-on experience showing important thermal properties of matter. So gather your materials, get ready, and let's get excited about thermodynamics with these amazing experiments! Science is waiting for YOU!