Heat Lab

Specific Heat Lab

Purpose: The purpose of this lab is to use what we know about energy and heat to determine an unknown block of metal given to us. The metal will either be aluminum, brass, copper, lead, stainless steel, or zinc. To determine which metal it is, I will place it in water, heat up the water, take the temperature of the water, and then place the metal in room temperature water and find the temperature difference. I will also use the weight of the metal to use it in an equation to find the temperature lost in the metal.

Background: As part of my some of background knowledge, I looked back to a food lab that I had done previously where we worked with calories. 1 calorie is the amount of heat needed to raise 1 gram of water. 1 °C of water is equal to 4.186 joules/gram. To find the heat of the metal and identify it, we will use the following equations:

 

 Qw=MwCw△Tw

Qw = heat water gained

Mw = mass of water

Cw = specific heat of water

△Tw = water after metal-before

 Qm=MmCm△Tm

Qw = heat water gained

Mm = mass of metal

Cm = specific heat of metal

△Tm = hot metal-cold metal

Specific Heats J

                      g(k)

Water = 4.184

Aluminum = 0.897

Brass = 0.385

Copper = 0.385

Lead = 0.385

Stainless Steel = 0.490

Zinc = 0.390

When the water reaches its boiling point with the metal in it, they will reach an equilibrium where the temperatures of both the water and metal will be the same. This is because the heat from the metal transfers to the water.

Materials:

• Two styrofoam cups. One will be cut shorter with a hole at the bottom to insulate the room temperature water
• Two beakers
• Metal Sample
• Water
• Hot Plate
• Metal Tongs
• Thermometer

Procedure:

1. Weigh cup and then weigh it with 150 ml water inside. This will be the room temperature water. Take the temperature of it and record

2. Weigh beaker and then weigh it with 150 ml of water in it. Record

3. Weigh metal. Record

4. Place metal in the water in the beaker, turn on hot plate, and place beaker on the hot plate

5. Wait until the water starts boiling. This indicates that they have reached an equilibrium. To make sure it is equal, wait 1 minute to take the temperature of the water.

6. Once the temperature has been taken, using the tongs, take the metal out of the beaker and place it in the room temperature water

7. Place the thermometer inside the cup until the temperature has stopped fluctuating. Record data

8. Clean up

Data:

Temp of room temperature water: 20.9 °C

Temp of hot water: 100 °C

Temp of hot metal: 100 °C

Temp of cold metal: 24.1 °C

Temp change of water: 3.2 °C

Temp change of metal: 75.9 °C

Weight of styrofoam cup: 2.026 g

Weight of cup w/150 ml water: 147.291 g

Weight of metal: 68.015 g

Calculations:

Qw=MwCw(△T)w

     (Mass of water)(Specific heat of water)(Room Temp water after-before)

Qw=(150)(4.184)(3.2)

Qw=2008.32 degrees Celcius

Qm=MmCm(△T)m

     (Mass of metal)(Cm)(Hot metal-cold metal)

2008.32 °C =(68.015)(Cm)(75.9)

2008.32 °C =(5162.34)(Cm)

2008.32 °C =(Cm)

5162.34

0.3890 = Cm

Conclusion:

The purpose of this experiment was to identify an unknown block of metal given to us using what we know about energy and heat. From my results, I concluded that my metal is zinc because the heat of zinc is 0.390 joules and my metal was 0.389 joules. I unfortunately did not have enough time to do any other trials for this lab to make sure my results were more accurate. Thankfully there was no major mistakes made in this lab except I probably could have been more accurate in my measurements such as when weighing things. I think I succeeded at fulfilling the purpose of this lab by how I was able to identify the metal.