11th grade states of matter

Question 1

How much energy is needed to boil away 1.5 kg of water at 100 °C, in kJ? (Specific latent heat of vaporisation of water = 2260 kJ/kg)

Answer kJ

Question 2

Why does sweating cool you down, in terms of latent heat?

• A. Sweat is colder than blood
• B. Evaporating sweat takes the latent heat it needs from your skin
• C. Sweat releases latent heat into the skin
• D. Sweat reflects sunlight

Question 3

133.6 kJ of energy melts or boils 0.4 kg of a substance with no change in temperature. What is its specific latent heat, in kJ/kg?

Answer kJ/kg

Question 4

How much energy is needed to melt 2 kg of ice at 0 °C, in kJ? (Specific latent heat of fusion of water = 334 kJ/kg)

Answer kJ

Question 5

On a heating curve for ice, why does the temperature stay at 0 °C for a while?

• A. Ice cannot be heated
• B. The heater has turned off
• C. Energy is destroyed while melting
• D. Energy is breaking bonds between particles to melt the ice, not raising their kinetic energy

Question 6

904 kJ of energy melts or boils 0.4 kg of a substance with no change in temperature. What is its specific latent heat, in kJ/kg?

Answer kJ/kg

Question 7

How much energy is needed to melt 0.2 kg of ice at 0 °C, in kJ? (Specific latent heat of fusion of water = 334 kJ/kg)

Answer kJ

Question 8

Why does sweating cool you down, in terms of latent heat?

• A. Sweat is colder than blood
• B. Sweat reflects sunlight
• C. Sweat releases latent heat into the skin
• D. Evaporating sweat takes the latent heat it needs from your skin

Question 9

1130 kJ of energy melts or boils 0.5 kg of a substance with no change in temperature. What is its specific latent heat, in kJ/kg?

Answer kJ/kg

Question 10

How much energy is needed to boil away 0.25 kg of water at 100 °C, in kJ? (Specific latent heat of vaporisation of water = 2260 kJ/kg)

Answer kJ

Question 11

Why is the latent heat of vaporisation of water much larger than its latent heat of fusion?

• A. Boiling happens at a lower temperature
• B. Boiling separates particles completely; melting only loosens them
• C. Melting needs more energy
• D. Water vapour has no particles

Question 12

41 kJ of energy melts or boils 0.2 kg of a substance with no change in temperature. What is its specific latent heat, in kJ/kg?

Answer kJ/kg

Question 13

How much energy is needed to boil away 0.1 kg of water at 100 °C, in kJ? (Specific latent heat of vaporisation of water = 2260 kJ/kg)

Answer kJ

Question 14

On a heating curve for ice, why does the temperature stay at 0 °C for a while?

• A. Energy is breaking bonds between particles to melt the ice, not raising their kinetic energy
• B. Ice cannot be heated
• C. The heater has turned off
• D. Energy is destroyed while melting

Question 15

267.2 kJ of energy melts or boils 0.8 kg of a substance with no change in temperature. What is its specific latent heat, in kJ/kg?

Answer kJ/kg

Question 16

How much energy is needed to boil away 0.5 kg of water at 100 °C, in kJ? (Specific latent heat of vaporisation of water = 2260 kJ/kg)

Answer kJ