Warm Up
1-19-16
1. Write a scenario where energy is transferred
(ex. making popcorn)
2. A hot frying pan is immersed in water.
Describe how heat is being transfer.
3. Turning gas to liquid a _____thermic reaction,
because ________
Agenda
Ice Melting Activity
Notes Unit 6-2
WS Specific heat
Homework
Finish WS
Ice Melting
•Place a small ice cube in a plastic beaker,
glass beaker, and metal rectangle
•Retry the experiment with different
amount of ice
•Were the temperature of the plastic, glass
and metal the same? (before you put ice on
them)
•How fast do ice melt on each material?
•Why do you think this happen?
Unit 6 - 2
Specific Heat
Heat vs. Temperature
•Heat is energy in transit
– Measured in joules (J) and calories (cal)
Heat vs. Temperature
Kinetic Energy: energy of
an object due to the
object’s motion
-Temperature - the measure of the average
kinetic energy of the random motion of
particles in a substance
– The hotter the substance, the faster the
particles are moving
Heat vs. Temperature
• Measured in 3 different temperature scales:
Fahrenheit, Celsius, and Kelvin
• Kelvin is based on absolute zero scale.
At zero °Kelvin, all molecules freeze &
stop moving
°K = °C + 273
°C = °K – 273
°C = (°F – 32) x 5⁄9
Heat vs. Temperature
• Celsius Scale
– 0o C - water freezes/melts
– 100o C - water boils
• Kelvin Scale
– 0 K- molecular motion stops,
also known as absolute zero
– 0 Kelvin = –273o C
Specific Heat
• Specific heat – the amount of energy
required to raise 1 gram of a substance by one
degree of temperature
• Water has a specific heat of 4.18 J/g·C
UNIT
• Transfer of heat does not always result in a
temperature change (ΔT)
CHECK IN
Which beaker will require
more heat to boil?
A
B
CHECK IN
The beaker with water and iron pan both
have the same mass. Which will get hotter
if the same amount of heat is applied to
both?
Calculating Specific Heat
• Different substances respond to heat transfer
differently
m x ΔT x Csp = Q
Symbol
Unit
Mass
m
g
Change in temperature
(Tfinal – Tinitial)
Specific heat
Heat energy
ΔT
K or C
Csp
Q
J/g·C
Joule
Calculating Specific Heat Problems
4 gram sample of glass was heated from
274 ° K to 314 °K and required 32 J of
energy. Find the specific heat of this glass
m x ΔT x Csp = Q
Calculating Specific Heat Problems
You are boiling 100 gram of water from room
temperature at 25°C to 100°C. How much
heat is required?
m x ΔT x Csp = Q
Calculating Specific Heat Problems
Determine the mass of a material its specific
heat is 2 J/g·K sample absorbed 48.0 J as it
was heated from 293 °K to 313 °K
m x ΔT x Csp = Q
Calculating Specific Heat Problems
The specific heat of aluminum is 0.89
J/goC. If 435 J of energy is added to
100g of aluminum. What is the ΔT?
ASSIGNMENTS
• Notes Summary
• Worksheet Specific Heat
Answers:
1. Specific heat
2. O Kelvin
3. Endothermic
4. Exothermic
5. 4.18
6. Delta T
7. O oCelcius
8. 0.416
9. 63,536 Joules
10. 7.974 g
11. 0.2
12. 13,794 joules
13. 0.031
Answers:
14. 27, 912 joules
15. 58,050 joules
16. 12.096 grams
17. 15.01818 Celsius
18. Object B, lower
specific heat means it
requires less heat for
temperature to
increase