Question

Heat produced on burning 6.3 g of a fule raises the temperature of 1.5 kg of water from 30⁰C to 60⁰C.Given that the specific heat of water is 4.2 J/g ⁰C.Calculate the calorific value of the fuel.

Answer 1

QUESTION

• Heat produced on burning 6.3 g of a fule raises the temperature of 1.5 kg of water from 30⁰C to 60⁰C. Given that the specific heat of water is 4.2 J/g ⁰C. Calculate the calorific value of the fuel.

EXPLANATION

Q = msΔt

Q = 1.5 x 4.2 x (60-30) x 1000

Q = 189 x 10³ J

Calorific value = 189 x 10³ / 6.3

= 30 kJ/g

Answer 2

Given: Heat produced on burning 6.3 g of a fuel raises the temperature of 1.5 kg of water from 30⁰ C to 60⁰ C. The specific heat of water is 4.2 J/g ⁰C.

To find: The calorific value of the fuel.

Solution:

• Heat produced on burning the fuel can be given by the formula,

        $Q = mc \delta T$

• Here, Q is the heat produced on burning the fuel, m is the mass of the water, c is the specific heat capacity of water and δT is the change in the temperature of the water due to the heat produced.
• The change in the temperature is calculated as,

        $60 - 30 = 30$

• On replacing the terms in the formula,

        $Q = 1.5 * 1000 g * 4.2 * 30$

            $= 189 * 10^{3} J$

• The calorific value can be found using the formula,

        $Calorific = \frac{Q}{(m)_{fuel}}$

• Here, m is the mass of the fuel.

        $Calorific = \frac{189 *10^{3}J} { 6.3 g}$

                         $= 30000 J/g$

                         $= 30 kJ/g$

Therefore, the calorific value of the fuel is 30 kJ/g.