Unit 3 Heat

Energy is transferred to water in a flask at a rate P. The water reaches boiling point and then P is increased. What are the changes to the temperature of the water and to the rate of vaporization of the water after the change?

• A

• B

• C

• D

Tags

NGSS.HS-PS3-4

Boiling water is heated in a 2 kW electric kettle. The initial mass of water is 0.4 kg. Assume the specific latent heat of vaporization of water is 2 MJ kg^–1.

What is the time taken for all the water to vaporize?

• 250 s

• 400 s

• 2500 s

• 4000 s

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

• 10 MPa

• 15 MPa

• 30 MPa

• 40 MPa

A substance changes from the solid phase to the gas phase without becoming a liquid and without a change in temperature.

What is true about the internal energy of the substance and the total intermolecular potential energy of the substance when this phase change occurs?

• A

• B

• C

• D

• 0.50

• 0.70

• 1.4

• 2.0

Tags

NGSS.HS-PS3-4

A liquid of mass m and specific heat capacity c cools. The rate of change of the temperature of the liquid is k. What is the rate at which thermal energy is transferred from the liquid?

Tags

NGSS.HS-PS3-4

A 700 W electric heater is used to heat 1 kg of water without energy losses. The specific heat capacity of water is 4.2 kJ kg^–1 K^–1. What is the time taken to heat the water from 25 °C to 95 °C?

• 7 s

• 30 s

• 7 minutes

• 420 minutes

Tags

NGSS.HS-PS3-1

Tags

NGSS.HS-PS3-2

• 1

• 2

A solid substance has just reached its melting point. Thermal energy is supplied to the substance at a constant rate. Which graph shows the variation of the temperature T of the substance with energy E supplied?

• A

• B

• C

• D

Tags

NGSS.HS-PS3-2

NGSS.HS-PS3-4