Latent Heat and Specific Heat Capacity

Latent heat is

• the heat absorbed or released at a boiling process during a change of phase

• the heat absorbed or released at a constant temperature during a change of phase

• the heat absorbed or released at a constant temperature during a change of phase of 1 kg object

• the heat absorbed or released by an object to increase or decrease its temperature by 1 degree Celcius

The heat absorbed by melting a solid is known as

• latent heat of fusion

• latent heat of solid

• latent heat of liquid

• latent heat of vaporisation

The amount of heat required to change the phase of a substance depends on two factors which are

• surrounding temperature

• temperature change

• material

• the mass

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

specific latent heat of vaporisation is

• the amount of heat required to change 1 kg of the substance from the solid to liquid phase without change in temperature

• the amount of heat required to change 1 kg of the substance from the liquid to gaseous phase without change in temperature

• the amount of heat required to change the temperature 1 kg of the substance by 1 degree Celcius

Tags

NGSS.HS-PS3-4

What is the formula to calculate specific latent heat of vaporisation?

• L = Q/m

• c = Q/(mΔƟ)

• Q = mcΔƟ

• Q = mL

Tags

NGSS.HS-PS3-4

The graph shows the cooling curve of a substance. At which stages the specific latent heat released?

• AB and CD

• BC and DE

• AB and EF

• BC and CD

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

Calculate the energy absorbed by 30 g of 100 ⁰C water that is turned into steam at100 ⁰C.

Specific latent heat of fusion = 3.34 x10⁵ Jkg^-1,

Specific latent heat of vaporization = 2.26 x 10⁶ Jkg^-1.

• 67 800 J

• 6 7800 J

• 678 J

• 67.8 J

Tags

NGSS.HS-PS3-1

Find the energy released by a copper block when it is cooled from 100^°C to 20^°C. Given that the heat capacity of the block is 770 J^°C^-1.

• 7.70x10⁴ J

• 8.61x10⁴ J

• 6.16x10⁴ J

• 5.02x10⁴ J

Tags

NGSS.HS-PS3-4

When an electric heater is supplied with an electric power of 2.0 kW to heat 4.0 kg of water for 1 minute, calculate the increase in temperature of the water. Assume that the specific heat capacity of water is 4200 J kg^{-1 0}C^-1 and there is no heat loss to the surroundings.

• 3.05⁰C

• 7.1⁰C

• 14⁰C

• 30⁰C

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

Danny pours some 95°C water into a cup of instant noodles. The final temperature of the mixture is 85°C. If the masses of the hot water and noodles are 500 g and 150 g respectively, find the specific heat capacity of the noodles.

Give that the original temperature of the noodles is 25°C and the specific heat capacity of the water is 4200 J kg^-1 °C^-1.

• 500 J kg^-1 °C^-1

• 1.08 x 10³ J kg^-1 °C^-1

• 2.33 x 10³ J kg^-1 °C^-1

• 6.00 x 10³ J kg^-1 °C^-1

Tags

NGSS.HS-PS3-4