SPECIFIC HEAT LAB
INTRODUCTION
Determining an unknown substance in chemistry is similar to police officers
determining weather a substance is a real drug or not. In chemistry, several different tests
are run just to determine what the unknown substance is. Police officers do the same
thing; such as finding a drug, putting drops of some sort of solution in it, and if it turns a
certain color they know if it’s fake or not. In chemistry you would do the same thing to
determine an unknown. Different tests that can be run in a lab are determining weather
the unknown is endothermic or exothermic. If the substance mixes with another
substance and lets off heat, it is exothermic. If the two substances mixed together feel
cold to the touch, it means that heat is being absorbed making it endothermic. Another
test would be to find the specific heat. Specific heat means the amount of heat nessesary
to raise the temperature of 1g of a substance 1 degree. So if the specific heat of an
unknown object can be calculated, then the identity of the unknown subject can be
determined.
MATERIALS AND METHODS
The lab was started out by getting a metal sample out of a little bucket. By the
looks of it, it appeared to be a piece of aluminum. The sample was weighed and
recorded. A stopwatch and thermometer were also retrieved and put on the lab station.
The metal was then placed in a boiling beaker of water that was set up before the lab.
The metal was then put in the water to heat for three minutes. While that took place, a
200mL beaker was retrieved and filled with 200mL of water. A foam soup bowl and lid
was brought back to the lab and made into a calorimeter. The 200mL of water was then
poured into the calorimeter. Two minutes after the water sat in the calorimeter; the
temperature was taken and recorded. After the metal had sat for three minutes, crucible
tongs were used to get it out. The sample was quickly shaken off, and set in the
calorimeter. The thermometer was then put through the lid, and the temperature was
taken every thirty seconds. The recordings were taken every thirty seconds until there
were four consecutive numbers in a row.
RESULTS
Mass of metal
Volume of water
Mass of water
57.99G
200 mL
200 g
T I metal (Boiling water)
94.55 oC
T I water/calorimeter
18.24 oC
T f system
19.02 oC
T metal
-73.53oC
T water/calorimeter
0.78 oC
s water
1 cal/goC
q water
119.89 cal
q metal
-119.89 cal
Equation 1) Heat = Mass x Specific Heat x Change in Temperature
Specific Heat of Metal = 94.55oC / 57.99 * 73.53oC
Temp (Celsius)
20
19.5
19
18.5
Temp
18
17.5
17
0
0.5
1
1.5
2
Time
2.5
3
3.5
CONCLUSION
If the specific heat of an unknown object can be calculated, then the identity of
the unknown can be determined. This hypothesis was proven correct because the specific
heat of the unknown in the lab was close to the specific heat of aluminum. The metal
was the only source of energy other than the boiling water because it was the only thing
warming up in the calorimeter. There wasn’t anything else in there but the piece of
aluminum. The water did absorb all of the metals heat because after three and a half
minutes of it being in the calorimeter, there were four consecutive temperatures in a row.
The metal was not the same temperature as the water the whole time. In the beginning it
was warmer when put in the water, but in the end did end up the same as the water. To
be honest, the only way the mass of the water was found was because of others in the
classroom. They said it was the same as how many mL there were. There weren’t many
problems with the lab, but the results were a little tricky. It was difficult until the chart
on the wiki was used and looked at. People have to find unknowns everyday. Not just
chemistry students or police officers, but everyday human people.