The Equilibrium Constant

Define chemical equilibrium.

• A reaction is reversible.
• The concentration of the reactants is equal to the concentration of the products.
• The rate of a forward reaction is equal to the rate of the reverse reaction.
• The reaction stops and no further change in concentration occurs.

Tags

NGSS.HS-PS1-6

Which of the following is NOT true at equilibrium?

• The forward and reverse reactions proceed at the same rate.
• The concentrations of reactants and products do not change.
• The concentration of the reactants is equal to the concentration of the products.
• The forward and reverse reactions continue to occur.

Tags

NGSS.HS-PS1-6

If the equilibrium constant is much greater than one (K >> 1) then

• Equilibrium is not established.
• Equilibrium lies to the right (products are favored)
• Equilibrium lies to the left (reactants are favored)
• Neither products or reactants are favored.

In the equation K_c = K_p(RT)^Δn , the Δn means

• The sum of all the moles.
• moles of products - moles of reactants
• moles of reactants - moles of product
• reaction order

Tags

NGSS.HS-PS1-7

N₂O₄(g) ↔ 2 NO₂(g)
What is the concentration equilibrium constant expression?

• K_c = [NO₂]²/[N₂O₄]
• K_c = [N₂O₄]/[NO₂]²
• K_c = [N₂O₄]²/[NO₂]
• K_c = [NO₂]/[N₂O₄]²

Tags

NGSS.HS-PS1-6

What is the equilibrium-constant expression for 
CO₂(g) + H₂(g) ↔ CO(g) + H₂O(l)

• K_c= [CO][H₂O] / [CO₂][H₂]  
• K_c= [CO₂][H₂] / [CO]
• K_c= [CO₂][H₂] / [CO][H₂O]
• K_c= [CO] / [CO₂][H₂]  

Tags

NGSS.HS-PS1-6

Find the K_c for
2NOBr(g) + Cl₂(g) ↔ 2NO(g) + 2BrCl(g)
 if 
2NOBr(g) ↔ 2NO(g) + Br₂(g)
has a K_c = 0.014
Br2(g) + Cl2(g) ↔ 2BrCl(g)
has a K_c = 7.2

• 0.10
• 10
• 1.0 x 10^-3
• 1.0 x 10^-2

Tags

NGSS.HS-PS1-6

What is the equilibrium expression for:
Fe₃O₄(s) + 4H₂(g) <--> 3Fe(s) + 4H₂O(g)

• ([Fe]³[H₂O]⁴ ) / ([Fe₃O₄][H₂]⁴)
• ([Fe₃O₄][H₂]⁴)/ ([Fe]³[H₂O]⁴)
• [H₂O]⁴ / [H₂]⁴
• ([Fe][H₂O]) / ([Fe₃O₄][H₂])

Tags

NGSS.HS-PS1-6

NGSS.HS-PS1-7

Keq < 1

• There are more products than reactants when the reaction reached equilibrium.
• There are more reactant than products when the reaction reached equilibrium.
  
• The amount of reactants is equal to the amount of products.

What kind of equilibrium does the reaction below show?
CaCO_{3 (s)} ↔ CaO _(s) + CO_{2 (g)}

• Heterogeneous equilibrium, all the reactants and products are in the same physical state.
• Homogeneous equilibrium, all the reactants and products are in the same physical state.
• Heterogeneous equilibrium, the reactants and products are present in more than one physical state
• Homogeneous equilibrium, the reactants and products are present in more than one physical state