Phase Changes

Which best describes the energy change that takes place during deposition?

Heat energy is released by the substance.

In which phase transition do molecules directly move from a state involving vibration of particles in a fixed position to a state involving random movement of high-speed particles?

Sublimation

Consider the heating curve for water. At what temperature does the solid start melting?

0°C

Consider the temperature versus time graph below. In which region is the substance in both the solid phase and the liquid phase?

2

Consider the heating curve. In which region are most particles moving the fastest?

5

Consider the temperature versus time graph below. At what temperature is the substance a heated gas?

Above 100°C

Consider the temperature versus time graph below. At what temperature is the boiling point of this substance?

At 120°C

Given below is the heating curve for iron. A company that manufactures iron spikes uses molds in which molten iron is poured. Based on the graph, which temperature range is best for pouring the iron?

Between 1600°C and 2600°C

Water is initially present in a state where its molecules are far apart. During a change of state, its molecules slow down. Which change of state has most likely taken place?

From a gas to a liquid.

Consider the following statement. "If a glass that contains ice is heated, the temperature of the water will most likely decrease while the ice melts." Is the statement true or false?

It is false because the heat that is added changes the phase and the temperature stays the same.

The diagram below shows the different phase transitions that occur in matter. Which arrow represents the transition in which dew is formed?

4

Substance X is present in a beaker. Its volume is not definite. Initially, the temperature of substance X rises. Later, its temperature suddenly decreases until another state of matter is formed. Which statement best describes this event?

Energy is first gained by substance X when it boils, and energy is then lost when it freezes.

In the diagram below, particles of the substance are moving from the liquid phase to the gas phase at the same rate as they move from the gas phase to the liquid phase.

Equilibrium

Jean has a sample of a liquid. If he changes the liquid's phase by _________ it, the molecules will spread out, allowing the sample to expand and to fill a container of any shape or volume.

Evaporating

The diagram below shows the different phase transitions that occur in matter. Which best describes the process that arrow 1 represents?

Molecules are speeding up during boiling.

The diagram below shows the different phase transitions that occur in matter. Which arrow would most likely represent the phase change that occurs when silver is poured into a mold and cools to become a solid bar?

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