AP Chemistry Spontaneity Entropy and Free Energy

True/False: The rate of a chemical reaction is unrelated to the spontaneity of the reaction.

• True

• False

A spontaneous reaction is more profitable to a company.

• True

• False

Tags

NGSS.HS-PS1-4

In a chemistry experiment, Liam, Maya, and Mason are trying to make a reaction happen between two chemicals to create a new compound. What factor can influence the reaction to occur?

• Enthalpy

• Entropy

• Both enthalpy and entropy

• Neither enthalpy nor entropy

Answer explanation

In a chemical reaction, both enthalpy and entropy play significant roles. Enthalpy is the heat content in a system and its change can drive a reaction. Entropy, on the other hand, is a measure of disorder or randomness. A reaction tends to occur if it leads to an increase in entropy. Therefore, both factors can influence the reaction to create a new compound in the chemistry experiment conducted by Liam, Maya, and Mason.

Tags

NGSS.HS-PS1-5

In a chemistry experiment, Noah, Daniel, and Luna are trying to determine the entropy of a substance in a real-world scenario. They are analyzing the melting of ice in a glass of water. What does entropy measure in this context?

• The randomness of a chemical

• The stability of a chemical

• The energy flow in a reaction

• The heat released in a reaction

Answer explanation

In this chemistry experiment, entropy refers to the degree of randomness or disorder in a system. As ice melts in a glass of water, it transitions from a more ordered state (solid) to a less ordered state (liquid), increasing the system's entropy. Therefore, the correct answer is 'The randomness of a chemical'.

Anika, Hannah, and William are helping Zoe in her science lab. They noticed that when Zoe increased the entropy of a system, something happened. What does Zoe observe when she increases the entropy in a real-world scenario like making a cup of hot chocolate?

• The reactions in her experiment start to happen

• The reactions in her experiment stop

• The reactions in her experiment become more stable

• The reactions in her experiment start to release energy

Answer explanation

In a real-world scenario like making a cup of hot chocolate, when Zoe increases the entropy of a system, the reactions in her experiment start to happen. Entropy is a measure of disorder, and an increase in entropy typically leads to a higher likelihood of reactions occurring, as the system becomes more disordered and less stable.

Tags

NGSS.HS-PS3-4

In a science class, Ethan, Isla, and Mason are discussing the concept of entropy. They want to know what entropy measures in the context of determining the entropy of a substance. Can you help them?

• Degree of disorder or randomness

• Pressure of the substance

• Temperature of the substance

• Amount of energy

Answer explanation

Entropy, in the context of science, measures the degree of disorder or randomness in a system. When determining the entropy of a substance, we are essentially quantifying how disordered or random the particles within that substance are. Therefore, the correct answer is 'Degree of disorder or randomness'.

Grace, Noah, and Abigail were baking a cake together. They noticed a change in the energy of the system during the chemical reaction between the ingredients. What is this change called?

• A decrease in energy during a chemical reaction

• An increase in energy during a chemical reaction

• The randomness of a chemical

• The stability of a chemical

Answer explanation

The change in energy during a chemical reaction, as observed by Grace, Noah, and Abigail, is called an increase in energy. This occurs when the energy of the system increases as the ingredients interact and form new bonds, resulting in the formation of the cake.

Tags

NGSS.HS-PS1-4

Benjamin and Charlotte are working on a chemistry project together. They observe an endothermic reaction when they mix two chemicals. What is the result of this endothermic reaction?

• An increase in energy

• A decrease in energy

• An explosion

• An increase in randomness

Answer explanation

In an endothermic reaction, energy is absorbed from the surroundings, causing an increase in energy. When Benjamin and Charlotte mix the two chemicals, they observe this type of reaction, which results in an increase in energy, making it the correct choice.

Tags

NGSS.HS-PS1-4

Emma, Hannah, and Samuel are conducting a chemistry experiment. They want to speed up the reaction. What factor can they manipulate to influence the reaction to occur faster?

• Adding a catalyst

• Increasing the temperature

• Increasing the pressure

• Increasing the volume

Answer explanation

In the given question, Emma, Hannah, and Samuel want to speed up a chemical reaction. Adding a catalyst is the correct choice because catalysts are substances that increase the rate of a reaction without being consumed. They work by lowering the activation energy required for the reaction to occur, thus making it happen faster.

Tags

NGSS.HS-PS1-5

The change in free energy of a chemical equation is represented by a

• △H

• △G

• △T

• △S