The heat produced on complete combustion of 20 g of a fuel could raise the temperature of 1.5 kg of water form 25^(@)C to 75^(@)C. Calculate the calorific value of the fuel if the specific heat capacity of water is 4.2 J g^(-1).^(@)C^(-1). Assume that the heat absorbed by the container is negligible.

The heat produced on complete combustion of 20 g of a fuel could raise

1.	The heat produced on complete combustion of 20 g of a fuel could raise the temperature of 1.5 kg of water form 25^(@)C to 75^(@)C. Calculate the calorific value of the fuel if the specific heat capacity of water is 4.2 J g^(-1).^(@)C^(-1). Assume that the heat absorbed by the container is negligible.
Answer» Solution :(i) Formula for calorfic value, Q=`msDeltatheta`. (ii) Find the amount of heat energy required to INCREASES the temperature of 1.5 `mug` of water from `25^(@)C` to `75^(@)C` using the formula Q=ms ...(i) Let 's' denote specific heat capacity of water and `'Delta theta'` denote change in the temperature. Is this heat energy RELEASED due to COMPLETE combustion of 20 g of a fuel ? Then, the formula related to combustion of fuel is Q=m.K. ....(2) Q=m.k =mwst, since heat released in combustion is absorbed by water. Thus, find the value of 'k' (iii) `15.75 kJ g^(-1)`