Question

When $150$ g sample of water cools from ${25}^{\circ }C$ to $5^{\circ }C$, the amount of heat released is :

(c for $H_{2}O$ is $4.18J/gK$)

• A. $720joules$
• B. $98joules$
• C. $78,375joules$
• D. $627joules$
• E. $12,540joules$

Answer 1

The correct option is E $12,540joules$

heat energy $=$ (mass) $\times$ (heat capacity) $\times$ (change in temperature)

$Q=m\times C\times \Delta T$

$Q=150g\times 4.18J/gK\times (25-5)K=12540J$