AP Chemistry Entropy and Gibbs Free Energy

Which process is accompanied by a decrease in entropy?

• boiling of water

• condensing of water vapor

• subliming of iodine

• melting of ice

Systems in nature tend to undergo changes toward

• lower energy and less disorder

• lower energy and more disorder

• higher energy and less disorder

• higher energy and more disorder

Given the change of phase:

CO₂(g) —> CO₂(s)

As CO₂(g) changes to CO₂(s), the entropy of the system

• decreases

• increases

• remains the same

Which phase change represents a decrease in entropy?

• solid to liquid

• gas to liquid

• liquid to gas

• solid to gas

Which one of these would result in a decrease in entropy?

• A solid solute dissolves in water.
• A gas is released.
• A liquid freezes.
• A liquid boils.

Entropy always increases when

• enthalpy decreases.
• temperature decreases.
• temperature increases.
• volume increases.

Tags

NGSS.HS-PS3-4

Spontaneous reactions are driven by

• increasing enthalpy and increasing entropy.
• decreasing enthalpy and decreasing entropy.
• increasing enthalpy and decreasing entropy.
• decreasing enthalpy and increasing entropy.

Solid magnesium dissolves in a hydrochloric acid, releasing hydrogen gas and heat from a solution of magnesium chloride. What is the sign on ΔH for this reaction?

• Negative because it is exothermic
• Negative because it is endothermic
• Positive because it is exothermic
• Positive because it is endothermic

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

Solid magnesium dissolves in a hydrochloric acid, releasing hydrogen gas and heat from a solution of magnesium chloride. What is the sign on ΔS for this reaction?

• Negative because it is becoming more ordered.
• Negative because it is becoming more disordered.
• Positive because it is becoming more ordered.
• Positive because it is becoming more disordered.

A reaction has a positive ΔH and a positive ΔS. Which of the following is true?

• It will be spontaneous at all temperatures.
• It will be nonspontaneous at all temperatures.
• It will be spontaneous at low temperatures.
• It will be spontaneous at high temperatures.