Latent Heat Lab

Within this lab, we did an experiment to find the latent heat of fusion and vaporization of water


To begin the lab, we started by theorizing what would happen if you expand a ring using heat

Our answer stats that the ring should theoretically expand infinitely

We then questioned what would occur to a bar of two differnet metal, Brass and Invar (knowing the the expansion of Invar is less than the expansion of Brass), should we heat it on each side of the metal

We theorized that when you heat the Invar side, the Brass side will bend, and vice-versa with heating the Brass side

Within the video, Prof Mason proves our theory to be wrong, showing that no matter which side you heat the metal to, it will always curve to the Invar side

Same concept as the heating, except instead of heating the metal, we cooled it to see if anything different changed.

Our next lab required this extensive setup of a steamer, a steel pole, and a wheel attached to the pole, spinning whenever the pole was expanding due to heat. Given the initial length, the initial and final temperatrure, and the diameter of the wheel, we were to find the constant (in 1/°C) of the pole, using the linear expansion formula ΔL=LoαΔT, where α is the constant we are calculating for

By converting the ΔL to its angular counterpart, rΔθ, we were able to calculate the α constant to about 1.2e-10 1/°C

We then moved on to the phases of water, and how they looked like when graphed experimentally. From chemistry, we were taught that the graphs are clean, straight, and linear.

The reality of phase changes

In reality, the curve looks a bit more parabolic than straight. Although the picture doesn't nessarily show it, until it hit a constant temperature at about 100°C, it rose and decline, which is not typical of what you would see in a chemistry book





Once we understood the truth about phase changes, we then moved on to calculating the heat of vaporization and fusion via experimentation. Here in this lab, there were no specific instructions on what to do, so instead, using the hints that Prof. Mason had kindly provided.

Our own ideas of how to do the lab

Using 100g of water and ice to make sure that there was just enough water for the immersion to stay submerse, while not taking too long to boil, we decided to use the following:

• Use paper towels in order to dry the ice
• By using a beaker, we can measure about the same amount of water as ice (since water is 1g/cc) and used the scale to measure the mass of the ice
• Place the water and beaker in a cold environment for 5 mins to let it reach to around 0°C (used the ice container along with a thermometer for this step)
• To find the Joules used, we can find the amount of power that the immersion released, and multiply it by its time.

To find the mass of the steam that escaped, we required the heat of vaporization, and can convert the equation as to look for the mass of the steam

Our graph, containing, with great accuracy, our specific heat of  water

Calculating the latent heat of fusion and of vaporization through experimentation