ET -- phase changes

The graph represents the heating of water in a pot. At 150 seconds, the water has just reached a boil. If the heat is left on, what will happen to the temperature and volume of water in the pot?

• The temperature will rise, and the water volume will decrease.

• The temperature will rise, and the water volume will remain constant.

• The temperature will remain constant, and the water volume will decrease.

• The temperature will remain constant, and the water volume will remain constant.

Which of the following statements is most accurate?

• When liquid water is heated, the molecules move faster.

• When liquid water is heated, the molecules collide more often.

• When liquid water is heated, collisions between molecules are more violent.

• All answers are correct.

In a pressure cooker, a lid is screwed tightly onto a pot so that the air pressure in the pot is increased. What effect, if any, will this have on the boiling point of water in the pot?

• The boiling point will be raised.

• The boiling point will be lowered.

• The boiling point will be unaffected.

• None of these answers is correct.

Which of the following descriptions explains the process of water freezing?

• Water molecules speed up until they escape into a different phase.

• Water molecules slow down until they begin to bond together.

• Water molecules are squeezed together by high pressure until they begin to stick to one another.

• As water molecules cool, their shape changes from rounded to irregular, making them more likely to link to one another.

The graph shows temperature changes as water reaches boiling point. Under what conditions would this situation occur?

• All conditions.

• Very high altitude.

• Very low altitude.

• Sea level.

Because heat is energy, the SI units for heat are ---

• Watts

• Celsius

• joules

• Newtons

 How much heat energy is needed to raise the temperature of 10.0 g of aluminum from 22°C to 55°C? The specific heat of aluminum is 0.90 J/g°C.    

• 297 J

• 0.003 J

• 297 J/g°C

• 0.003 J/g°C

What does the delta (triangle) T represent in the equation?

• the specific heat

• the temperature

• change in temperature

• the total heat energy