Minnesota Boiler License Practice Exam

What is the latent heat of water from solid (ice) to liquid (water) and from liquid to gas (steam) in BTUs?

1. 144, 970

2. 320, 244

3. 1, 1000

4. 50, 800

The correct answer is: 144, 970

The transformation of water from solid to liquid and then from liquid to gas involves significant energy changes, measured in British Thermal Units (BTUs). When ice melts into liquid water, the energy required to overcome the molecular forces holding the ice together is known as the latent heat of fusion. This latent heat is approximately 144 BTUs for each pound of ice. Following this, when liquid water is converted into steam, a second phase change occurs that requires even more energy, referred to as the latent heat of vaporization. The latent heat of vaporization for water is around 970 BTUs for each pound of water. When you add these two values together, it totals roughly 1,114 BTUs (144 + 970), which can sometimes be approximated or rounded. The provided answer lists 144 BTUs for the ice to water transition and 970 BTUs for the water to steam transition, making the choice accurate for both latent heat processes combined. It’s important to note that the other options may refer to different phase changes or simply incorrect values for the latent heat of water transitions. The principle of latent heat is critical in thermodynamics and boiler operations, where understanding the amount of energy required for these changes directly impacts water and