Phase Change Problems

A sample of water is cooled from 45°C to 25°C by the removal of 20. calories of heat. What is the mass of the water?

• 10 g

• 1.0 g

• 20 g

• 200 g

The number of calories needed to raise the temperature of 10 grams of water from 20°C to 30°C is

• 10

• 20

• 100

• 40

A 5.0-gram sample of water is heated and the temperature rises from 10.°C to 15°C. The total amount of heat energy absorbed by the water is

• 25 cal

• 20 cal

• 15 cal

• 5 cal

The graph represents the uniform heating of a water sample at standard pressure, starting at a temperature below 0°C. If 5 grams of water undergoes a temperature change from C to D, the total energy absorbed is (a)   .

• 80 calories

• 100 calories

• 180 calories

• 500 calories

How many calories of heat energy are released when 50 grams of water are cooled from 70°C to 60°C?

• 10 calories

• 50 calories

• 500 calories

• 1,000 calories

How many calories of heat are absorbed when 50. grams of water at 100.°C are completely vaporized?

(Heat of vaporization = 540 cal/g)

• 590

• 5400

• 27000

• 54000

The heat of fusion of water is 80 calories per gram. How many calories of heat would be required to completely melt 5 grams of H₂O(s) at 0°C to H₂O(ℓ) at 0°C?

• 5

• 40

• 80

• 400

The heat given off by an acid solution as it is neutralized by a base solution could be measured by using a (a)   .

• eudiometer
• pH meter
• calorimeter
• colorimeter

What is the maximum number of grams of water at 10.°C that can be heated to 30.°C by the addition of 40.0 calories of heat?

• 1.0 g

• 2.0 g

• 20 g

• 30 g

The temperature of 100 grams of water changes from 16°C to 20°C. What is the total number of calories of heat energy absorbed by the water?

• 25

• 40

• 100

• 400