Answer to Question #141641 in General Chemistry for Elyza

Question

1. How much heat does it take to increase 100g of water 17K?

2. How much heat does it take to melt 150g of water?

3. How much heat does it take to melt 150g of water?

4. If a substance has a heat of fusion that is 500J/g and a heat of vaporization that is 1000J/g how much heat would it take to melt a 10g sample?

Answer 1

1.

$\begin{aligned} H &= mc\triangle \theta\\ \\ m &= 100g\\ \triangle \theta &= 17K\\ c &= 4.184\ J/gcm^3\\ \\ H &= 100 × 4.184 × 17\\ H &= 7,112.8J \end{aligned}$

2.

$\textsf{I assume you meant melt 150g of ice}\\ m = 150g\\ \\ \textsf{To melt 150g of ice to water, we use; }\\ H = mL\\ where\ L = 334\ J/g\\ H = 150 × 334\\ H = 50,100J$

3.

$\textsf{I assume you meant melt 150g of ice}\\ m = 150g\\ \\ \textsf{To melt 150g of ice to water, we use; }\\ H = mL\\ where\ L = 334\ J/g\\ H = 150 × 334\\ H = 50,100J$

4.

$L_f = 500\ J/g\\ L_v = 1000\ J/g\\ m = 10g\\ \textsf{To melt, we use } H = mL_f\\ H = 10 × 500\\ H = 5000J$

$\therefore$ 5000J is needed to melt 10g of the sample.