Heat of Vaporization

The video explains how matter changes states, focusing on the transition between solid, liquid, and gas. It introduces the concept of heat of vaporization, which is the energy required for a substance to change from liquid to gas. The video also discusses phase changes at a molecular level, highlighting the role of hydrogen bonds in water. It covers the significant volume change during vaporization, which is the principle behind steam engines. Finally, it explains how boiling and condensation occur at constant temperatures, with energy used for state changes rather than temperature changes.

What is the term for the energy required to change a substance from liquid to gas?

• Heat of fusion

• Heat of vaporization

• Heat of condensation

• Heat of sublimation

What happens to hydrogen bonds in water as it heats up?

• They transform into ionic bonds

• They become stronger

• They remain unchanged

• They weaken

What is the main reason water turns into steam?

• Increase in atmospheric pressure

• Addition of salt

• Decrease in temperature

• Complete breaking of hydrogen bonds

By how much does the volume of water increase when it changes from liquid to gas?

• 700-fold

• 1000-fold

• 100-fold

• 500-fold

What remains constant when water boils at 100 degrees Celsius?

• The mass

• The pressure

• The temperature

• The volume