Arkansas Boiler Operator Practice Exam

What happens to water when it reaches 212 degrees F at atmospheric pressure?

1. It freezes

2. It boils and turns to steam

3. It remains liquid

4. It evaporates without boiling

The correct answer is: It boils and turns to steam

At atmospheric pressure, water boils and turns to steam when it reaches 212 degrees Fahrenheit. This temperature is known as the boiling point of water at sea level, where the atmospheric pressure is approximately 14.7 psi. At this point, the thermal energy supplied to the water causes the molecules to move faster, breaking the intermolecular bonds that keep them in the liquid state. As a result, water transitions from its liquid form to a gaseous form (steam). This phase change occurs without a change in temperature; the water will continue to absorb heat until all of it has changed into steam. The boiling point can vary with changes in pressure. For example, in higher altitudes where atmospheric pressure is lower, water will boil at a temperature lower than 212 degrees Fahrenheit. Nonetheless, at standard atmospheric pressure, boiling occurs at this specific temperature. Other scenarios such as freezing, remaining liquid, or evaporating without boiling do not take place at this boiling point under normal atmospheric conditions.