Heat Capacity And Specific Heat Capacity

• Heat capacity
• Specific heat capacity

MEASUREMENT OF HEAT ENERGY

In order to assess the quantity of heat energy possessed by a body, three quantities are needed.  They are:

• the change in temperature (θ)
• the specific heat capacity of the body (C)
• mass of the body (m)

It is measured in Joules

Heat capacity

This is the quantity of heat required to raise the temperature of a substance by one degree.  It is measured in Joules/K.

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Specific heat capacity

Specific heat capacity of a substance is the heat required to raise the temperature of a unit mass of the substance through one degree change in temperature

The quantity of heat Q received by a body is proportional to its mass (m), and temperature change  and on the nature of the material the body is made of.

DETERMINATION OF SPECIFIC HEAT CAPACITY BY MIXTURE METHOD (PRACTICAL)

DETERMINATION OF SPECIFIC HEAT CAPACITY BY ELECTRICAL METHOD (PRACTICAL)

Specific Heat Capacity Problems & Calculations – Chemistry Tutorial

CLASSWORK 2 & 3

1. Define is heat capacity?
2. A metal of mass 0.5kg is heated to 100⁰C, transferred to a well lagged calorimeter of heat capacity 80 J/k containing water of heat capacity 420 J/k at 15⁰C.  If the final steady temperature of the mixture is 25⁰C, find the specific heat capacity of the metal
3. Explain the meaning of the statement, the specific heat capacity of a substance is 777JKg^-1K^-1

ASSIGNMENT 2 & 3

SECTION A

1. A waterfall is 630m high. What is the change in temperature of a quantity of water that falls from the top to the bottom of the waterfall? [Neglect heat lost to the surroundings, take acceleration due to gravity as 10ms^-2 and Specific capacity of water as 4200 JKg^-1K^-1] (a) 0.15⁰C (b) 1.50⁰C (c) 15.0⁰C (d) 21.0⁰C (e) 150.0⁰C
2. An electric heater rated 12V is used to heat 450g of water when a current of 5A was passed through it. What is the final temperature after 30minutes?  [Specific capacity of water = 4200 JKg^-1K^-1] (a) 57k (b) 20k (c) 57k (d) 80k (e) 40k
3. If 60g of water at 90⁰C is poured into a calorimeter containing 20g of water at 30⁰C, calculate the final steady temperature of the mixture (a) 90⁰C (b) 75⁰C (c) 68⁰C (d) 25⁰C (e) 101⁰C
4. How much heat is required to change 10kg of an object from 20^OC to 70^OC? [Specific heat capacity of the object is 200JKg^-1K^-1](a) 1×10⁵J    (b) 1×10⁴J    (c) 40J (d) 10⁵J (e) 40×10⁵J
5. Which of the following is not used to determine the heat content of a body? (a) mass of the body (b) volume of the body (c) specific heat capacity of the body (d) temperature of the body (e) all of the above

SECTION B

1. A piece of copper of mass 120g is heated in an enclosure to a temperature of 125⁰C.  It is then taken and held in the air for 30 seconds and dropped carefully into a copper calorimeter of mass 105g containing 200g of water at 20⁰C.  The temperature of the water rises to 25⁰C. Calculate the rate at which heat is being lost from the copper when it is held in the air. [Specific heat capacity of copper = 400 JKg^-1K^-1, Specific capacity of water = 4200 JKg^-1K^-1]
2. An immersion heater supplies heat at the rate of 500Js^-1 (i) what is quantity of heat produced in 24 minutes (ii) if there is no heat loss, calculate the rise in temperature if a brass of 3kg initially at 30⁰C absorbed all the heat produced by the heater