Entropy and Thermodynamics Regents Level Quiz

Even though melting an ice cube requires heat, it can still melt at room temperature. Which natural tendency accounts for this phase change?

• a tendency toward greater entropy

• a tendency toward greater energy

• a tendency toward less entropy

• a tendency toward less energy

Imagine you are making a homemade cold pack using potassium nitrate (KNO3). When KNO3 dissolves in water, it absorbs 34.89 kJ of heat from the surroundings. What can you say about this process?

• It is endothermic and entropy increases.

• It is endothermic and entropy decreases.

• It is exothermic and entropy increases.

• It is exothermic and entropy decreases.

As the temperature of a cup of coffee increases, the entropy of the coffee

• decreases

• increases

• remains the same

In a chemical factory, a certain reaction is taking place: N2(g) + 3 H2(g) ⟶ 2 NH3(g) + heat. This is known as the Haber process. If you were to categorize this reaction, how would you describe it?

• It's like a bonfire that burns brightly and causes the surrounding air to become more chaotic (exothermic, with an increase in entropy)

• It's like a bonfire that burns brightly but makes the surrounding air more ordered (exothermic, with a decrease in entropy)

• It's like ice melting on a hot day, causing the surrounding air to become more chaotic (endothermic, with an increase in entropy)

• It's like ice melting on a hot day but makes the surrounding air more ordered (endothermic, with a decrease in entropy)

Which list of the phases of H2O is arranged in order of increasing entropy?

In a campfire, when a piece of charcoal burns in the presence of oxygen to produce carbon dioxide and release heat, which phrase best describes this reaction?

• exothermic with an increase in entropy

• exothermic with a decrease in entropy

• endothermic with an increase in entropy

• endothermic with a decrease in entropy

The entropy change (ΔS) in a refrigerator is equal to the

• entropy of the food items after cooling minus the entropy of the food items before cooling

• entropy of the food items before cooling minus the entropy of the food items after cooling

• heat content of the food items after cooling minus the heat content of the food items before cooling

• heat content of the food items before cooling minus the heat content of the food items after cooling

Answer explanation

The entropy change (ΔS) in a refrigerator is equal to the entropy of the food items before cooling minus the entropy of the food items after cooling.

A cup of hot coffee is left on a table in a room. Over time, it is most likely to undergo a change so that in its final state, as compared to its initial state, the cup of coffee has

• cooled down and its heat has spread throughout the room (increased entropy)

• cooled down and its heat has remained within the cup (decreased entropy)

• heated up and its heat has remained within the cup (decreased entropy)

• heated up and its heat has spread throughout the room (increased entropy)

What happens when a room full of scattered toys is tidied up?

• The room has greater entropy and less order.

• The room has greater entropy and more order.

• The room has less entropy and less order.

• The room has less entropy and more order.

In which scenario will a process always occur naturally?

• A hot coffee cooling down and becoming less disordered

• A hot coffee cooling down and becoming more disordered

• A cold coffee heating up and becoming less disordered

• A cold coffee heating up and becoming more disordered