Question

When 25.0 grams of water are cooled from 20.0 degrees Celsius to 10.0 degrees Celsius the number of joules of heat energy released is?

Answer 1

Answer: 1045 J of energy was released on cooling the down the water from 20 °C to 10 °C.

Explanation:

Specific heat of water : 4.18J/g °C(standard value)

$Q=mc\Delta T=$

Q= Energy released

m = mass of the substance

c = specific heat value of a substance

$\Delta T$ = Change in temperature

For 25 g of water the Q released when cooled down to 20 °C to 10 °C will be:

$Q=mc\Delta T=25 g\times 4.18J/g ^oC\times (10^oC-20^oC)=-1045 J$

Q = -1045 J (negative sign indicates that energy is released)

1045 J of energy was released on cooling the down the water from 20 °C to 10 °C.