1. Specific Heat
4/28/17

2. Heat is the ___Transfer___ of energy due to a change in temperature
OUCH! Why can you still burn your fingers by touching the metal handle of a pot on the stove even when the water is only lukewarm? The heat is still there…in the water. It holds 10x’s more heat than the iron pot!
The __Specific Heat __ of water is very high; it takes a lot of energy to raise one gram of water 1 degree Celsius.

3. Calories to Joules
_1_calorie = Joules 1 kilocalorie = ___1000____ calories. ( a kilocalorie is the same thing as “big C” Calorie)

4. SPECIFIC HEAT CAPACITY
The amount of heat (in calories or Joules) that must be added or removed from a __gram___ of that substance to change its temperature by ____1˚C__.
WHEN THERE IS HEAT/ENERGY INVOLVED: 
Q (heat energy) = m (mass) x Δt (temp.) x cp (specific heat capacity) (cal/Joules) (g) (°C) (cal/g °C) or (Joule/g °C)

5. Problem 1
How much heat energy is needed to raise the temperature of 100 grams of water from 0 degrees to 30° C? (the specific heat of water is J/(g°C)
Find your variables:
Q=?
m= 100 g
ΔT= 30° C - 0° C = 30° C
Cp = 4.18 J/(g°C)
Solve for Q… 12,540 J or KJ

6. Problem 2
A calorimeter contains 300 grams of water at 10° C. After a food sample is burned in the calorimeter the water temperature changes to 15° C. How much heat was given off by the food sample?
Can you recall the specific heat of water from the last problem?? You’re going to need it.

7. Problem 3
What amount of heat is required to raise the temperature of 85.9 g of water by 7C? The specific heat of water is J/gC.

8. Problem 4
What amount of heat is required to increase the temperature of 75.0 g of water from 22.3C to 36.1C? The specific heat of water is J/gC.

9. Problem 5
How much energy is required to increase the temperature of 100 grams of water from 25 C to 85 C?

10. Problem 6
How much water can absorb calories of heat if the temperature changes 5 degrees?
Can we use the specific heat value for water we have been using (4.18 J/gC.) ?
No we cannot! The Problem asks for calories not Joules. We must use 1 c/g °C

11. Problem 7 q(water) = m c (T-22.3) q(silver) = m c (T-100)
You place g of water in a coffee-cup calorimeter and the temperature of the water is 22.3C. A 94.5 g piece of silver metal is heated to 100.0C and added to the water in the calorimeter. What will the final temperature of the silver and the water be? The specific heat of silver is J/gC.
q(water) = m c (T-22.3)
q(silver) = m c (T-100)
set the two equations equal to each other
q(water)= -q(silver)