A Substance Has a Melting Point Of $20 ^ { \circ } \mathrm { C }$

question 73

Multiple Choice

A substance has a melting point of $20 ^ { \circ } \mathrm { C }$ and a heat of fusion of $3.6 \times 10 ^ { 4 } \mathrm {~J} / \mathrm { kg }$ The boiling point is $150 ^ { \circ } \mathrm { C }$ and the heat of vaporization is $7.2 \times 10 ^ { 4 } \mathrm {~J} / \mathrm { kg }$ at a pressure of one atmosphere. The specific heats for the solid, liquid, and gaseous phases are $600 \mathrm {~J} / \mathrm { kg } \cdot \mathrm { K } \text { (solid) , } 1000 \mathrm {~J} / \mathrm { kg } \cdot \mathrm { K } \text { (liquid) , and } 400$ $\mathrm { J } / \mathrm { kg } \cdot \mathrm { K } \text { (gaseous) . }$ How much heat is given up by 2.80 kg of this substance when it is cooled from $170 ^ { \circ } \mathrm { C } \text { to } 86 ^ { \circ } \mathrm { C }$ at a pressure of one atmosphere?

• A) 640 kJ
• B) 300 kJ
• C) 200 kJ
• D) 400 kJ
• E) 440 kJ

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