August 26 - Temperature Scales, Methane Fire Bubble, Aluminum Can, Heat vs Temperature

Temperature Scales

Finding Relationship Between Fahrenheit and Celsius

The relationship between Fahrenheit and Celsius was found by graphing the boiling and freezing points of both and drawing a line between the two.  The slope of the line was found to be m=9/5 °C/°F, the y intercept was found to be +32°C and the relationship between the two was linear

  

 Methane Fire Bubble

Prediction of Methane Bubble

We began the experiment by blowing a bubble and observed that even though the hot air inside the bubble was probably lighter than the air outside the bubble, the bubble still sank due to the weight of the bubble.  Then the bubble was going to be filled with methane and we predicted that the bubble would rise due to the methane being so much lighter than the air that it would overcome the weight of the bubble.  The weight of the bubble can be seen by the small arrow below the bubble in the right hand corner of the picture and the methane pulling the bubble up can be seen by the much larger arrow above the bubble. 

Methane Bubble Sheet of Fire

We then caught the bubble on fire, which we predicted the bubble would float up at a faster rate, but it can be seen in the video that the bubble expanded into a sheet of fire.  The reason this happened is because when the heat approached the bubble it caused the kinetic energy of the particles in the bubble to move faster and bounce around the walls of the bubble so when the bubble burst the particles went out to the side in the sheet formation.  The particles also had an initial upward momentum so the sheet of fire also rose up.

 Aluminum Can

Testing how heat flow worked with water

Before we began the Aluminum Can experiment we first tested how heat flow worked.  We tested with by adding 50 grams of water that was at 65 °C and 50 grams of water that was at 25 °C that hit equilibrium at 45 °C.  We then did another test by adding 100 grams of water at 25°C to 50 grams of water at 65°C, the temperature dropped to 38.3°C due to the extra cold water.  

Aluminum Can Molecules

Logger Pro Graph of Temperature Change

 We then began the test with the aluminum can.  We added 50 grams of hot water that was around 68 °C into a mug that was holding 100 grams of cold water that was around 23°C and measured the two temperature changed using logger pro and two temperature probes, one which was placed into the hot water and one that was placed into the cold water.  It can be seen that it took much longer for the water to reach equilibrium because of the aluminum can insulating the hot water within it.                                                                                                                                                 Even though the can was insulating the hot water within the can, the molecules in the hot water were moving fast which made the molecules in the can begin to move fast which in turn made the molecules within the mug begin to move faster until the whole system was moving at the same rate (this is when it reached equilibrium at about 34°C).  

Cooling Water Faster

We then brainstormed and found five different ways we cold make the heat transfer faster.  

 Heat vs Temperature

Graphs drawn from Logger Pro

A 300 Watt immersion heater was used in this part of the lab to study heat transfer.  If no heat is lost to surroundings, then a 300 Watt immersion heater should produce 6000 J of power in 20 s.  All of this information was then tested.  First we tested the immersion heater and found that it only produces 294.4 Watts instead of 300.  We then placed the immersion heater into 200 mL of water for 20 seconds and measured the initial and final temperatures using logger pro and the temperature probes.  The graph was initially set up to measure temperature vs time and within our 20 seconds with the probe in the water, the temperature of the water jumped from about 22 °C to 28 °C.                        

Logger Pro Temp vs Heat

We then modified the graph to measure temperature vs heat instead of temperature vs time and we made the heat column by multiplying the 294.4 Watts of our immersion heater to the "time" column and it could be seen that the heat jumped from 4000 J to about 11000 J within those 20 seconds.                                                                                                                                                            

Logger Pro Heat vs Temp

After, the graph was again changed to measure Heat vs Temperature and it could be seen that there is a linear relationship between heat and temperature.  A best fit linear line was plotted and the slope was found to be 1069 J/°C.  

Logger Pro Heat Per Unit Mass vs Temp

The graph was then changed one last time to now measure heat per unit mass vs temperature.  This was obtained by dividing our heat that we calculated by the mass of the water (200 grams of water).  A linear line could be seen after the graph was made and a best fit linear line was placed on the graph and the slope was 5.316 J/g°C.  The heat per unit mass vs temperature slope was actually how they were able to come up with the number 4.18 J/g°C of the specific heat of water, and our value was not far off from the actual value.  

Descriptions of heat per unit mass vs temp graph