AP Chemistry Unit 7 Equilibrium

What happens at equilibrium?

• The rate of the forward reaction is faster than the rate of the reverse reaction

• The rate of the reverse reaction is faster than the rate of the forward reaction

• The rates of the forward and reverse reaction are equal

Tags

NGSS.HS-PS1-6

 $2NaOH\ +H_2SO_4\ \leftrightarrow\ Na_2SO_4\ +\ 2H_2O$  
What is the expression for the equilibrium constant of the above reaction? (Assume all compounds are gases)

•  $K=\frac{\left[Na_2SO_4\right]\left[H_2O\right]^2}{\left[NaOH\right]^2\left[H_2SO_4\right]}$ 
  

•  $K=\frac{\left[Na_2SO_4\right]\left[H_2O\right]}{\left[NaOH\right]\left[H_2SO_4\right]}$  

•  $K=\frac{\left[NaOH\right]^2\left[H_2SO_4\right]}{\left[Na_2SO_4\right]\left[H_2O\right]^2}$  

•  $K=\frac{\left[NaOH\right]\left[H_2SO_4\right]}{\left[Na_2SO_4\right]\left[H_2O\right]}$  

Tags

NGSS.HS-PS1-6

At a particular temperature 10.0 mol NH₃ gas is placed in a 1.0-L container. Over time the NH₃ decomposes to H₂ and N₂:

2NH₃(g) ↔ N₂(g) + 3H₂(g)

At equilibrium the concentration of N₂(g) was found to be 2.4 mol/L. Calculate the value of K for this reaction (using units of mol/L for the concentrations).

• K= 3.3

• K= 33

• K= .030

• K= .30

Tags

NGSS.HS-PS1-6

CO(g) + H₂O (g) ↔ CO₂(g) + H₂(g)

Determine the equilibrium concentration for H₂ if the equilibrium concentration of CO₂ was 3.4 mol/L.

• 3.4 mol/L

• 6.8 mol/L

• 2.1 mol/L

• 1.0 mol/L

Tags

NGSS.HS-PS1-6

A table showing Ksp values for several magnesium compounds is given above. A saturated solution of which of the compounds has the greatest molar concentration of Mg²⁺ (aq)?

• MgBr₂

• MgO

• MgF₂

• All the compounds have the same molar concentration

Tags

NGSS.HS-PS1-6

If the products are favored in a reaction, what is the value of K?

• K<1

• K>1

• K=1

• K=0

Tags

NGSS.HS-PS1-6

The equilibrium constant, K_c, for the following reaction is 23.1 at 300 K.

2Br₂(g) + 2H₂O(g) ↔ 4HBr(aq) + O₂(g)

Assuming that you start with equal concentrations of Br₂ and H₂O and no HBr or O₂ is initially present, describe the relative abundance of Br₂ at equilibrium.

• Lower than products

• Higher than products

• Same as products

• Can't tell

Tags

NGSS.HS-PS1-6

HCl(g) + H₂O(g) ↔ Cl^-(aq) + H₃O⁺(aq)

When 0.31 moles of HCl(g) are removed from the equilibrium system at constant temperature, the reaction must

• Run in the forward reaction to reestablish equilibrium

• Run in the reverse reaction to reestablish equilibrium

• Remain the same. It is already at equilibrium.

Tags

NGSS.HS-PS1-5

NGSS.HS-PS1-6

2SO₂(g) + O₂(g) ↔ 2SO₃(g) K_c = 22

The table lists the initial concentrations of each substance in the system represented by the equation above at a given temperature. Which of the following best predicts what will occur as the system approaches equilibrium?

• The rate of the reverse reaction will be greater than the rate of the forward reaction, because K_c < Q_c.

• The rate of the forward reaction will be greater than the rate of the reverse reaction, because K_c < Q_c.

• The rate of the reverse reaction will be greater than the rate of the forward reaction, because K_{c >} Q_c.

• The rate of the forward reaction will be greater than the rate of the reverse reaction, because K_{c >} Q_c.

Tags

NGSS.HS-PS1-5

NGSS.HS-PS1-6

At what time is equilibrium established in the graph?

• 2000

• 4000

• 6000

• 8000

Tags

NGSS.HS-PS1-6