If the heat given off by 300 g of an alloy as it cools through 50 Cº is sufficient to raise the temperature of 300 g of water from 30º to 40ºC,the specific heat of the alloy must be approximately
A)0.015 cal/g · Cº
B)0.10 cal/g · Cº
C)0.15 cal/g · Cº
D)0.20 cal/g · Cº
E)0.50 cal/g · Cº

Question

Quizplus · Accepted Answer

The heat lost by the alloy is equal to the heat gained by the water. Using the formula $Q = mc\Delta T$, where $m$ is mass, $c$ is specific heat, and $\Delta T$ is the temperature change, we equate the heat lost by the alloy to the heat gained by the water. For water, $Q = 300 \times 1 \times 10 = 3000$ cal. For the alloy, $300 \times c \times 50 = 3000$. Solving for $c$, we get $c = 0.20$ cal/g·Cº.

If the Heat Given Off by 300 G of an Alloy