Transcript No Slide Title

Point of Today
Name: __________________
Date: _________ Period: ___
o
1. Review
. Heating Curves
2. Introduce Heat
3. Introduce
. Specific Heat
4. Change in
. Temperature
Substance Specific Heat (J/g C)
Water
4.18
Grain Alcohol
2.4
Ice
2.1
Wood
1.8
Steam
1.7
Chloroform
0.96
Aluminum
0.9
Iron
0.46
Silver
0.24
Mercury
0.14
Q = Heat in joules (J)
m = mass in grams (g)
c = specific heat (J/goC)
T = Change in
Temperature(oC)
1gram
1
Specific heat “c” is the amount of heat
needed to increase 1 gram of a
substance 1oC
15.0o C
Heat
1. How much heat is given off by 55 g of water as it cools from 87o C to 25oC?
2. Calculate the amount of heat that must be absorbed to raise the temperature of a
4.75 g aluminum sample from 25.0oC to 26.8oC
3. A. Calculate the amount of joules needed to raise a 15.0 g sample of water from 25o C
to 100.0oC.
Water Calculation:
B. Now calculate the amount of joules needed to raise a 15.0g sample of grain
alcohol from 25oC to 100.0oC.
Grain Alcohol Calculation:
5. Solve Problems
. Using Q = mc∆T
16.0oC
C. Explain why there is a difference in the heat required preform A and B?
Heating Curve
100o------------------------------------------
Boiling Water
Heating
Steam from
100o - ???
Heating water from 0o - 100oC
0o ----------- Melting Ice
Heating Ice to 0oC
Thermodynamics
Q = mc T
Heat
Mass
Specific
Heat
Change
in Temp
Q is measured in Joules
Joules = J
Kilojoules = kJ (1000 J)
4.18 calories = 1 kJ
Substance Specific Heat (J/g oC)
Water
4.18
Grain Alcohol
2.4
Ice
2.1
Wood
1.8
Steam
1.7
Chloroform
0.96
Aluminum
0.9
Iron
0.46
Silver
0.24
Specific Heat Capacity = c
The amount of heat needed to
o
raise 1.0 g of a substance 1.0 C
1 gram
16.0oC
15.0o C
Specific Heat = c
Substance Specific Heat (J/g oC)
Water
4.18
Grain Alcohol
2.4
Ice
2.1
Wood
1.8
Steam
1.7
Chloroform
0.96
Aluminum
0.9
Iron
0.46
Silver
0.24
∆ = Change
Change in Temperature: ∆T
∆T = (Tfinal - Tinitial)
Initial
Final
The temperature changed from 10oC to 50oC.
T=
o
(50 C
-
o
10 C)
Change in Temperature =
o
40
C
1. How much heat is given off by 55 g of water as it
cools from 87o C to 25oC?
Substance Specific Heat (J/g oC)
Water
4.18
Grain Alcohol
2.4
Ice
2.1
Wood
1.8
Steam
1.7
Chloroform
0.96
Aluminum
0.9
Iron
0.46
Silver
0.24
Tfinal - Tinitial
Q = mcT
Q = (55g)(4.18J/goC)(25oC - 87oC)
Q = - 14253.8 J 1 kJ = -14 kJ
1000 J
2. Calculate the amount of heat that must be absorbed to raise the
temperature of a 4.75 g aluminum sample from 25.0oC to 26.8oC
Substance Specific Heat (J/g oC)
Water
4.18
Grain Alcohol
2.4
Ice
2.1
Wood
1.8
Steam
1.7
Chloroform
0.96
Aluminum
0.9
Iron
0.46
Silver
0.24
Q = mcT
Tfinal - Tinitial
Q = (4.75g)(0.9 J/goC) (26.8oC - 25.0oC)
Q = 7.695 J 1 kJ = 0.00770 kJ
1000 J
Different Specific Heats
Qsteam= mc T
100o------------------------------------------
Qwater= mc T
0o -----------
Use the Chart
Qice= mc T
Time