1. Specific Heat
Specific heat – the quantity of energy needed to increase the temperature of one gram of a substance by 1 K or 1 ºC
Every substance has its own unique specific heat.
Ex) Specific heat of liquid water is 4.18 J/(g·K)

2. Specific Heat Formula for Heat: Q = heat/energy m = mass
Cp = specific heat (of a substance)
∆T = Tfinal — Tinitial = change in temperature

3. Specific Heat Units: Q= calories, cal, or joules, J m = grams, g
∆T = degrees Celsius, ⁰C, or Kelvin, K
Cp = a derived unit, so may be different
Example:
J/(g•ºC)

4. Example #1: Conversions needed? No. Intermediates needed? Yes.
An unknown substance with a mass of 50. g is heated from 298 K to 373 K. While heating, the substance absorbs 750. J of energy. What is the specific heat of the unknown substance?
I. Given and unknown
Conversions needed? No.
Intermediates needed? Yes.
VI. Solve
II. Formula

5. Example #2:
How much heat is required to raise the temperature of 109 g of Tin from 27⁰C to 61⁰C? (Cp of Tin =
0.228 J/g• ºC)

6. Example #3:
If 5.0 g of H2O at 298 K absorbs 830 J of heat, what is the final temperature of the H2O? (Hint: Find the specific heat of water somewhere in your notes!)

7. Calorimetry Energy is conserved.
During an exothermic process, the water in the
calorimeter will gain any heat lost by the system.
During an endothermic process, the water in the
calorimeter will lose any heat gained by the system.
At constant pressure, Q = ∆H

8. Example #1:
A calorimeter contains g of water. When 2.80 g of gasoline is combusted, it changes the temperature of the water in the calorimeter from 298 K to 330. K. How much heat does this chemical process release?
I. Given and unknown
Conversions needed? No.
Intermediates needed? Yes.
VI. Solve
II. Formula

9. Example #2:
A 28.4 g sample of aluminum is heated to 39.4 oC, then is placed in a calorimeter containing 50.0 g of water. Temperature of water increases from oC to oC. What is the specific heat of aluminum? (Hint: Specific Heat of water is 4.18 J / (g oC)

10. Example #3:
A lump of chromium (Cr) has a mass of 95.3 grams and a temperature of 90.5⁰C. It is placed into a calorimeter with 75.2 mL of water at 20.5⁰C. After stirring, the final temperature of the water, Chromium metal, and calorimeter is 28.6⁰C. What is the specific heat of Cr metal?