Question

14. What is the total number of kilojoules of heat needed to change 150. G of

Answer 1

Answer:

$\boxed {\boxed {\sf 50.1 \ kJ}}$

Explanation:

When water changes from ice (solid) to water (liquid), it is melting or fusion. Therefore, we can use the following formula to find energy:

$q=mH_f$

where q is the energy, m is the mass, and Hf is the heat of fusion.

1. Define Values

The mass is 150 grams. The heat of fusion for water is 334 Joules per gram.

$m= 150 \ g \\H_f=334 \ J/g$

2. Calculate Energy

Substitute the values into the formula.

$q=150 \ g * 334 \ J/g$

Multiply. Note that the grams (g) will cancel each other out and leave Joules as our units.

$q=150 *334 \ J$

$q=50100 \ J$

3. Convert Units

We found the answer in joules, but the question asks for kilojoules, so we must convert.

There are 1000 Joules in 1 kilojoule. Therefore, we can divide the joules calculated by 1000.

$50100 \ J *\frac{1 \ kJ}{1000 \ J}$

$\frac{50100 \ kJ}{1000 \ }$

$50.1 \ kJ$

50.1 kilojoules are needed to change 150 grams of ice to water.