The heat of fusion of a substance is 42.5 J/g. How much energy is released when 40 g of this substance

Question

at its freezing point completely changes into a solid?
answers:
2.5 J
1.06 J
0J
1,700 J

Answer 1

To calculate the energy released when 40 g of the substance changes from a liquid to a solid at its freezing point, we can use the heat of fusion formula:

\[ \text{Energy} = \text{mass} \times \text{heat of fusion} \]

Given:

• Heat of fusion = 42.5 J/g
• Mass = 40 g

Now, substitute these values into the formula:

\[ \text{Energy} = 40 , \text{g} \times 42.5 , \text{J/g} = 1700 , \text{J} \]

Therefore, the energy released is 1,700 J.