AP Chemistry Review: Unit 7

At equilibrium, concentrations of reactants and products are

• equal

• constant

Tags

NGSS.HS-PS1-6

At what time does the system first reach equilibrium?

• 24s

• 40s

• 60s

• 80s

Tags

NGSS.HS-PS1-6

H₂ gas and N₂ gas were placed in a rigid vessel and allowed to reach equilibrium in the presence of a catalyst according to the following equation.

3 H₂(g) + N₂(g) ⇄ 2 NH₃(g)         ΔH^o = -92 kJ/mol_rxn

The diagram below shows how the concentrations of H₂ , N₂ , and NH₃ in this system changed over time. What occurs from t1 to t2?

• The concentration of N₂ decreased.

• The number of effective collisions between H₂ and N₂ was zero.

• The rates of the forward and reverse reactions were equal.

• The rate of formation of NH₃ molecules was equal to the rate of disappearance of H₂ molecules.

Tags

NGSS.HS-PS1-6

NGSS.HS-PS1-5

H₂(g)+I₂(g)⇄2HI(g)

Hydrogen gas reacts with iodine gas at constant temperature in a sealed rigid container. The gases are allowed to reach equilibrium according to the equation above. Which of the following best describes what will happen to the reaction immediately after additional iodine gas is added to the system?

• The rates of both the forward and reverse reactions decrease.

• The rates of both the forward and reverse reactions do not change.

• The rate of the forward reaction becomes greater than the rate of the reverse reaction.

• The rate of the forward reaction becomes less than the rate of the reverse reaction.

Tags

NGSS.HS-PS1-5

H₂(g) + I₂(g) ⇄ 2HI(g)

A 1.0mol sample of H₂(g) and a 1.0mol sample of I₂(g) are placed in a previously evacuated 1.0L container and allowed to reach the equilibrium shown above. If the equilibrium concentration of HI(g) is 0.40M, which of the following is the value of the equilibrium constant?

• 0.16

• 0.25

• 0.44

• 1.0

Tags

NGSS.HS-PS1-6

Given the K_c for a forward reaction, how can you find K_c for the reverse reaction?

• Divide K_c by 1

• Divide 1 by K_c

• Square K_c

• Take the square root of K_c

For the reaction...

SO₂ + O₂ <−> SO₃

If the concentration of SO₂ is increased, the system will shift ___________.

• left

• right

• left and right

• neither left nor right

Tags

NGSS.HS-PS1-6

NGSS.HS-PS1-5

For the reaction...

heat + N₂ + O₂ ↔ 2NO

If heat is added to the chemical system, the system will shift _______.

• left

• right

• left and right

• neither left nor right

Tags

NGSS.HS-PS1-6

NGSS.HS-PS1-5

2SO₂ (g) + O₂ (g) ⇌ 2SO₃ (g)

Decreasing the volume of container will

• shift the system right

• shift the system left

• change K

• have no effect

Tags

NGSS.HS-PS1-6

An equilibrium constant with a large value, e.g. K_c = 1000, indicates…

• A very fast reaction
• Mostly products at equilibrium
• Mostly reactants at equilibrium
• Nothing useful at all

Tags

NGSS.HS-PS1-6