Water and changes of state

If you want to change liquid water into a gas you must:

• remove heat from the water
• apply pressure to the water
• add heat to the water
• add chemicals to the water

Suppose you pour a glass of ice water and set it on the kitchen table. After a few minutes, the outside of the glass will be covered with drops of water. Why did this happen?

• Oxygen in the air cooled and condensed onto the cold glass.
• Water vapor in the air cooled and condensed onto the cold glass.
• Water vapor in the air cooled and evaporated onto the cold glass.
• Water seeped through pores in the glass.

What is the opposite of melting?

• condensation
• evaporization
• freezing
• sublimation

Which is needed for both boiling and melting to occur?

• solids
• gases
• heat
• pressure

 The process where water vapor changes from a gas to a liquid is called:

• sublimation
• precipitation
• evaporation
• condensation

During which of the following processes does water gain heat?

A Freezing

B Condensation

C Boiling

D Evaporation

• A and B only

• A and D only

• B and C only

• C and D only

A beaker of ice was heated over a period of time. The changes in temperature are shown in the graph.

Which of the following correctly matches the processes to the parts of the graph?

• Melting: AB Boiling: BC

• Melting: AB Boiling: CD

• Melting: BC Boiling: AB

• Melting: BC Boiling: CD

Jed filled a beaker with water and left it in a room at 27^oC. After a few minutes, Jed observed water droplets on the outer surface of the beaker.

Which of the following is most likely the temperature of the water in the beaker?

• 10^oC

• 37^oC

• 50^oC

• 100^oC

Ameera wants to conduct an experiment to find out if ice melts faster when more heat is applied to it. Which of the following variable(s) should she keep the same?

A Amount of ice used

B Amount of heat applied

C Shape of container used

D Location at which the experiment is conducted

• B only

• A and C only

• A, C and D only

• A, B, C and D

Which of the following statements describe the similarities between melting of ice and the freezing of water?

A Heat is gained in both processes.

B Both processes take place at 0^oC.

C Both processes involve a change of state.

• A and B only

• A and C only

• B and C only

• A, B and C