Phase changes and Latent Heat

The graph shows the temperature of 1kg samples of three materials, A, B, and C, as they are heated. Heating occurs at a constant rate.

If material A starts to melt at 60 ^oC. At that point, the line on the graph will __________.

• continue on as before

• begin to curve upward

• become steeper

• become horizontal

The graph shows the temperature of 1kg samples of three materials, A, B, and C, as they are heated. Heating occurs at a constant rate.

Which material has molecules with the highest average kinetic energy after 40 s of heating?

• Material A

• Material B

• Material C

• Impossible to determine from the graph

A 45.0-kg sample of ice is at 0.00 ^oC. How much heat is needed to melt it? For water L_f =334,000 J/kg and Lv =2.256×10⁶ J/kg.

• 1.50×10⁴ kJ

• 4.10×10⁶ kJ

• 0.00 kJ

• 1.02×10⁵ kJ

A system consists of an ice cube floating in a glass of water. The entire system is at 0 ^oC. Thermal energy is then added slowly to the system, causing half of the ice to melt. What can be said about the resulting temperature of the system?

• Greater than 0 ^oC

• Less than 0 ^oC

• Equal to 0 ^oC

• Equal to 100 ^oC

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

The heat energy required to change 1 kg of a substance from a solid to a liquid state at the same temperature is called ____

• specific heat capacity

• specific latent heat of vaporization

• sensible heat

• specific latent heat of fusion

What is the thermal energy removed to convert 0.5 kg of water at 0 ^oC to ice at 0 ^oC ?

• 0 J

• 1.5 × 10⁵ J

• 3.0 × 10⁵ J

• 6.0 × 10⁵ J

Consider the following temperature-time graph when a solid is heated. which part of the graph involves latent heat of vaporization?

• Part I

• Part II

• Part III

• Part IV

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

This formula is used to find the amount of heat (energy) neccesary when there's a phase change

• Q= (h)(ΔT)

• Q=(m)(L)

• Q=(m)(c)(ΔT)

• Q=(k)(A)(dT)

How much energy is required to freeze 150 g of water? ( L_V=2260 and L_F=334)

• 50 100 cal

• 339 000 J

• 339 000 cal

• 50 100 J

How much energy is required to heat up a 25 kg jug of water from 10°C to 15°C? (c_s=2.11 and c_L=4.18)

• 522.5 J

• 263.75 J

• 263 750 J

• 522 500 J