Heat Capacity

  • Home
  • Heat Capacity
Shape Image One
  • No Comments
  • Admin
  • April 10, 2023
9th Physics Ch#09 Thermal Properties Of Matter Heat Capacity

Heat Capacity

advanced divider

Heat Capacity:

Heat capacity, also known as thermal capacity, is the measure of the amount of heat energy required to raise the temperature of an object by a certain degree. It is expressed in units of energy per unit of temperature change, typically in joules per kelvin (J/K) or calorie

s per degree Celsius (cal/°C). The heat capacity of an object depends on its mass, composition, and temperature, as well as the specific heat of its components.

Heat capacity is an important concept in thermodynamics, as it determines how much energy must be added or removed from an object in order to change its temperature.

Mathematically, 

C= ΔQ / ΔT 

Where  Q  = Amount of heat absorbed and (ΔT) is change in temperature.

Heat capacity depends upon the nature of material.

Example:

Two breakers contain equal masses of water and oil is heated by the same gas burner for three minutes. Then it is observed that the temperature of oil may rise twice than water.

Specific Heat Capacity:

When comparing the heat capacity of different substances, we are actually talking about their specific heat capacity.
Hence specific heat capacity can be defined as:

(C =ma) c = C/m = 1/m(ΔQ / ΔT )

C= ΔQ / ΔT………….

Where “c’’ is constant which depends upon the nature of material of the body.this constant is called specific heat capacity or specific heat. Its SI unit is joule per kilogram per Kelvin (J kg-1– K-1).

Effect Due to Large Specific Heat of Water

We know that water has a large specific heat, due to this quality it plays an important role in everyday life.This property of water has several important effects:

  1. Water helps regulate the temperature of the environment: The high specific heat of water allows it to absorb a large amount of heat from the environment without a significant rise in temperature. This property of water helps regulate the temperature of the environment, which is important for the survival of many organisms.
  2. Water moderates temperature changes in organisms: The high specific heat of water also helps moderate temperature changes in organisms. Organisms that live in water, such as fish, can maintain a relatively stable internal temperature despite changes in the temperature of the surrounding water.
  3. Water helps regulate the Earth’s climate: The high specific heat of water plays an important role in regulating the Earth’s climate. The oceans absorb a large amount of heat from the sun, which helps to moderate temperature changes in the atmosphere. This property of water helps prevent extreme temperature changes and helps to maintain a relatively stable climate.
  4. Water is important for cooking: The high specific heat of water makes it an ideal substance for cooking. Water can absorb a large amount of heat energy without rapidly increasing in temperature, which allows food to be cooked at a relatively constant temperature.

Worked Example

The thermal energy required to raise  the temperature of 50g of water from 40oC to 70oC is 6300 Joules. Calculate the specific heat capacity of water.

Step 1:

T1 = 40°C

T2 = 70°C

ΔT = T2 – T1 = 70°C – 40°C = 30°C = 30K

ΔQ = 6300 J

m = 50 g = 0.05 kg

c = ?

Step 2: Write down the formula and rearrange if necessary

C = ΔQ / (m × ΔT)

Step 3: Put the values in formula and calculate

c = 6300 J / (0.05 kg × 30 K) = 4200 J kg-1 K-1

Hence, specific heat of water is c = 4200 Jkg-1 K-1.

Quiz

advanced divider
Previous Topic
Back to Lesson
Next Topic