Unit 7 Post Assessment Remediation (PAR)

Which phase change results in an increase in entropy?

• I₂(g) → I₂(s)

• CH₄(g) → CH₄(l)

• Br₂(l) → Br₂(g)

• H₂O(l) → H₂O(s)

During which two processes does a substance release energy?

• freezing and condensation

• freezing and melting

• evaporation and condensation

• evaporation and melting

The graph represents the uniform heating of a sample of a substance starting as a solid below its melting point.

Which statement describes what happens to the energy of the particles of the sample during time interval DE?

• Average kinetic energy increases, and potential energy remains the same.

• Average kinetic energy decreases, and potential energy remains the same.

• Average kinetic energy remains the same, and potential energy increases.

• Average kinetic energy remains the same, and potential energy decreases.

The graph represents the uniform cooling of a sample of a substance, starting with the substance as a gas above its boiling point.

Which segment of the curve represents a time when both the liquid and the solid phases are present?

• EF

• BC

• CD

• DE

In the heating curve, heat is applied to a solid substance at a constant rate.

What accounts for the fact that segment CD is longer than segment AB?

• Boiling occurs at a higher temperature than melting.

• The heat of vaporization is greater than the heat of fusion.

• The average kinetic energy increases at a greater rate during boiling than during melting.

• Potential energy is being released during boiling.

Solid aluminum has a specific heat capacity of 0.90 J/g•K. How many joules of heat are absorbed to raise the temperature of 24.0 grams of aluminum from 300. K to 350. K?

• 22 J

• 45 J

• 1100 J

• 1200 J

At standard pressure, the total amount of heat required to completely vaporize a 100.-gram sample of water at its boiling point is

• 2.26 × 10 J

• 2.26 × 10² J

• 2.26 × 10³ J

• 2.26 × 10⁵ J

What is the vapor pressure of propanone at 45°C?

• 21 kPa

• 60. kPa

• 70. kPa

• 79 kPa

At 50.°C and standard pressure, intermolecular forces of attraction are strongest in a sample of:

• ethanoic acid

• ethanol

• propanone

• water 

Which graph best represents the pressure-volume relationship for an ideal gas at constant temperature?

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