Endothermic and Exothermic Reactions

Which statement describes this phase change in terms of energy and entropy? Given the equation representing a phase change for carbon dioxide, CO₂(s): CO₂(s) + energy → CO₂(g)

• The phase change is endothermic and entropy increases.

• The phase change is endothermic and entropy decreases.

• The phase change is exothermic and entropy increases.

• The phase change is exothermic and entropy decreases.

Given the potential energy diagram for a reaction: Which interval on this diagram represents the difference between the potential energy of the products and the potential energy of the reactants?

• 1

• 2

• 3

• 4

Tags

NGSS.HS-PS1-4

Which statement correctly describes the energy changes that occur in the forward reaction?

• The activation energy is 10. kJ and the reaction is endothermic.

• The activation energy is 10. kJ and the reaction is exothermic.

• The activation energy is 50. kJ and the reaction is endothermic.

• The activation energy is 50. kJ and the reaction is exothermic.

Tags

NGSS.HS-PS1-4

Which information about a chemical reaction is provided by a potential energy diagram?

• the oxidation states of the reactants and products

• the average kinetic energy of the reactants and products

• the change in solubility of the reacting substances

• the energy released or absorbed during the reaction

Tags

NGSS.HS-PS1-4

Which arrow represents the potential energy of the reactants?

• A

• B

• C

• D

Tags

NGSS.HS-PS1-4

The activation energy required for a chemical reaction can be decreased by

• increasing the surface area of the reactant

• increasing the temperature of the reactant

• adding a catalyst to the reaction

• adding more reactant

A catalyst will

• lower the activation energy

• increase the activation energy

An example of a catalyst is a

• carbohydrate

• protein, specifically an enzyme

• lipid

• nucleic acid

What is the approximate change in enthalpy (H) for the formation of 1 mole of water? 2 H₂(g) + O₂(g) → 2 H₂O(ℓ) + 571.6 kJ

• -285.8 kJ

• +285.8 kJ

• -571.6 kJ

• +571.6 kJ

Tags

NGSS.HS-PS3-1

According to Reference Table I, which statement best describes the formation of HI(g)? H₂(g) + I₂(g) → 2HI(g)

• It is exothermic, and heat is released.

• It is exothermic, and heat is absorbed.

• It is endothermic, and heat is released.

• It is endothermic, and heat is absorbed.

Tags

NGSS.HS-PS1-4