Lab 2 Linear and Volume expansion of materials by thermal conduction ->Brass ring expansion, Differences in Thermal Expansion, Linear Thermal Expansion Demo, Latent Heat<-

Brass ring expansion

Prediction

One of the first experiment we did was the demonstration of teacher increasing temperature of metal ring. In room temperature, the metal ball would not go through the metal ring.

Question involved the hole: When the brass plate is heated up by the gas burner shown in the photograph, the hole will:  

• (a) get bigger. (predicted and was correct)
• (b) get smaller.
• (c) remain the same size. 

The process of heating the metal ring using a blow torch fueled by propane.

The heating process continues and it almost seemed no difference to naked eye but it can now let the metal bball go through the hoop.
Analytical learning points: linear thermal expansion is demonstrated here by the brass hoop enlarging as it gets higher temperature. Also, this indicates that metal or other solid material expands when heated, in particular brass, will expand at such a distance between any two points on the metal plate increases by the same ratio. The distance between two adjacent corners, or two diagonal corners, or diameter across the hole. However, there is one expansion especially excluded is that the brass does not expand into the hole, which is supported by the demonstration.

Differences in Thermal Expansion
Furthermore, professor Mason demonstrated the properties of Thermal Expansion difference of different materials, with the help of bimetallic strip: one side with invar(alloy of nickel and iron) and other side with brass.
Heating up of Bimetallic strip. 3 tests performed by professor Mason.

Picture showing prediction bimetallic strip when it was heated from the invar side and heated from brass side. Our prediction was that it will bend toward invar side on both demonstrations because of invar's lower linear and volumetric coefficient. 

This is the video shows that the curvature is happening toward the invar side when heat is applied

Bend toward Invar side by heating from brass side.

on both the brass side and invar side.

Bimetallic strip heating on Invar

Bimetallic Strip Cooling Demonstration

Analysis:

During the course of this video, we have learned that the bimetallic strip will indeed bend toward the invar side because the invar has a much lower linear and volumetric coefficient. From the three events we see three effects supporting the importance of volumetric coefficient of materials reacting to heat and cold.

In this picture, we calculated the alpha of steel from the given values. and drew a prediction graph.

Below (2) are more pictures showing the setup for melting ice.

The three pictures above are demostrated by Professor Mason to see the expected shape of the graph according to real time experiment.

This picture is the setup for experiment.

Another example of thermal expansion

This picture is for the final value from our measurement. This graph is similar to the graph Professor mason have except with fluctuations in the graph during the initial setup with the uneven stirring force applied.

From doing the experiment above of testing the fusion of water, ice's specific heat, and water's specific heat, we find that we were close but not that accurate, And the values we find are Cw=4.22J/g, Lf=421.6J/g, and Lv=1408J/g

This is the Q
Overall

Expected Lf, Cw, Lv	Accepted kj/(kgK)	Percent discrepancy
421.6	334	27%
4.22	4.186	0.012%
1908	2256	15%

Expected Lf, Cw, Lv

Accepted kj/(kgK)

Percent discrepancy

421.6

334

27%

4.22

4.186

0.012%

1908

2256

15%

As one can see, for the latent heat of fusion and the specific heat of water calculated, the values were larger than the accepted values. This is due to many factors. Error could have been present in the tools used such as LoggerPro itself and the device used to measure the temperature. 

This was the graph teacher's experiment

Below are uncertainty calculations for Lf, Cw, Lv

Uncertainty:

Ulv=234.34J/g

Ulf=15.35J/g

Ucw=0.2734J/g/K

The water did not boil at 100ºC, instead it boiled at 96.2ºC. There could have been error in the experiment as well. The lab was done in a glass beaker, a material that does not insulate heat as well as styrofoam or another material and so accurate data could have been lost through glass absorbing some of that heat. For the latent heat of vaporization, the calculated value was higher than the actual. This could be due to using the calculated value of the specific heat of water. We used a calculated value to calculate another and this added to the error. Overall, the percent error as not large for Lf and Lv. and this is most likely due to error in reading the graph from LoggerPro. It was difficult to find the right spot on the graph for the times and temperature that the system no longer had anymore ice and so this could be a reason to such a high amount of error of 27% and and 15% compared to a good error amount from specific heat of 0.012%. From knowing the uncertainty and comparing to the percent discrepancy, one can see only the Cw is inside the uncertainty range. 

Interesting Things learned: Don’t make floors out of brass!