Reaction Rates and Equilibrium

When a spark is applied to a mixture of hydrogen and oxygen, the gases react explosively. Which potential energy diagram best represents the reaction?

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Tags

NGSS.HS-PS1-4

Which statement BEST describes how a catalyst affects a chemical reaction?

• the temperature of a reaction will increase

• the activation energy of a reaction will decrease

• the activation energy of a reaction will increase

• it will decrease the frequency of molecular collisions in the reaction

Tags

NGSS.HS-PS1-4

As collisions increase between reactants, the rate of reaction also increases. Which of the following does not cause an increase in collisions between reactants?

• Increase in temperature

• Decrease in surface area

• Increase in pressure

• Addition of a catalyst

Tags

NGSS.HS-PS1-5

Which of the options below would result in an increased rate of reaction?

• using a larger piece of a reactant

• storing reactants in the refrigerator

• increasing concentration of reactant

• diluting the reactant before the reaction

Tags

NGSS.HS-PS1-5

When a system has reached equilibrium, the reverse reaction rate is

• faster than the forward reaction rate.

• equal to the forward reaction rate.

• equal to zero.

• slower than the forward reaction rate.

Tags

NGSS.HS-PS1-5

NGSS.HS-PS1-6

The rates of reaction for both the reverse and the forward reaction of a reversible reaction are shown in the graph on the left. Which of the following statements is true when the reaction reaches an equilibrium state?

• The rates of the reverse and forward reactions are equal at equilibrium.

• The forward reaction rate is higher than the reverse reaction rate at equilibrium.

• Both the reverse and forward reactions stop when equilibrium is reached.

• The amount of product formed decreases when equilibrium is reached.

Le Chatelier's principle can be used to predict how changes in ________ affect a system in chemical equilibrium.

• concentration and temperature

• concentration, temperature, particle size, and catalysts

• concentration, temperature, and pressure

• concentration, temperature, and catalysts

Tags

NGSS.HS-PS1-5

Why are solids eliminated from equilibrium expressions?

• Pressure does not affect them.

• Their concentrations are always zero.

• Their concentrations do not change.

• Their concentrations are always one.

This is a balanced chemical equation. CO(g) + H2(g) ⇌ CO(g) + H2O(g) These are the molecular concentrations for each substance: [CO2] = 0.0954 M, [H2] = 0.0454 M, [CO] = 0.0046 M, [H2O] = 0.0046 M. What is the equilibrium constant (Kc) for this reaction?

• 99306.31

• 0.0049

• 2.10

• 204.69

Tags

NGSS.HS-PS1-7

Nitrogen gas (N2) and hydrogen gas (H2) are in a state of equilibrium with ammonia (NH3) as described in the reaction system below. N_2(g) + 3H_2(g) ⇌ 2NH_3(g) Which expression represents the equilibrium constant for this reaction?

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Tags

NGSS.HS-PS1-7