Let's Calculate Heat Release When Water Freezes!

How do we solve for the KJ of heat that would be released?

When something in a liquid or semi-liquid freezes, it undergoes a phase change to a solid state, and this process involves a release of heat.

For example, when water freezes, it releases 333.5 kJ of heat per kg of water that freezes.

To be able to calculate the heat released, we need to use the formula:

q = m x Lf

But first, we must convert grams to kg:

Now, let's calculate the heat released:

The total KJ of heat that would be released is

B. -83.5 kJ

When a liquid or semi-liquid freezes, it goes through a phase change to become a solid, and during this transition, heat is released. In the case of water, it releases 333.5 kJ of heat for every kilogram (kg) that freezes.

To calculate the heat released (q), we use the formula q = m x Lf, where q is the heat released, m is the mass of the substance, and Lf is the heat of fusion (in this case, 333.5 kJ/kg).

By converting 250 grams (g) to kilograms (kg), we get 0.25 kg. Substituting this value into the formula, we find that the heat released when 250g of water freezes is 83.375 kJ. Since heat is being released, the answer is represented as -83.5 kJ.

Understanding how heat is released during phase changes like freezing is crucial in various fields of science and engineering. By mastering these concepts, we can better comprehend the behavior of different substances under different conditions.