When a catalyst is added to a reaction, a decrease occurs in the

• activation energy

• heat of reaction

• potential energy of the reactants

• potential energy of the products

Which statement describes characteristics of an endothermic reaction?

• The sign of △H is positive and the products have less potential energy then the reactants

• The sign of △H is negative, and the products have less potential energy than the reactants

• The sign of △H is positive and the products have more potential energy then the reactants

• The sign of △H is positive, and the products have more potential energy than the reactants

Tags

NGSS.HS-PS1-4

Given the change of phase: CO₂(g) changes to CO₂(s), the entropy of the system

• remains the same

• You cannot determine the answer with the given information.

• increases

• decreases

Which tendencies favor a spontaneous reaction?

• decreasing enthalpy and decreasing entropy

• increasing enthalpy and increasing entropy

• increasing enthalpy, and decreasing entropy

• decreasing enthalpy and increasing entropy

Which phrase best describe the following reaction 2H₂ + O₂ --> H₂O + energy?

• endothermic, absorbing energy

• endothermic, releasing energy

• exothermic, releasing energy

• exothermic, absorbing energy

Tags

NGSS.HS-PS1-4

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

• △H

• △G

• △T

• △S

A 0.20 kilogram sample of lead at 120⁰C is put in to a calorimeter containing 0.30 kg of water at 18⁰C. The equilibrium temperature of the mixture is 20.⁰C. Compared to the heat lost by the lead, the heat gained by the water is

• the same

• less

• more

Tags

NGSS.HS-PS3-4

The changes in ice to water involve

• and absorption of heat and an increase in entropy

• a release of heat and an increase in entropy

• a release of heat and a decrease in entropy

• an absorption of heat and a decrease in entropy

Two metals of equal mass but different specific heats absorb the same amount of heat. Which metal undergoes the smaller change in temperature?

• You cannot determine from the information given.

• Both undergo the same change in temperature.

• The metal with the higher specific heat.

• The metal with the lower specific heat.

Tags

NGSS.MS-PS3-4

NGSS.MS-PS3-5

A substance that changes the rate of a reaction but is neither consumed nor changed is

• a catalyst.

• an activated complex.

• an intermediate.

• a reaction.