Equilibrium Constant (Kc or Keq)

Consider the following reaction. What would be the equilibrium constant expression?
4Br₂(g) + CH₄(g) ⇋  4HBr(g) + CBr₄(g)

• [Br₂]⁴  [CH₄]/ [HBr]⁴  [CBr₄]
• [HBr]⁴ [CBr₄]/ [Br₂]⁴ [CH₄]
• [HBr ]/ [Br₂]⁴ [CH₄]
• [HBr]⁴ [CBr₄]/ [Br₂]⁴ [CH]⁴

At what time (in seconds) is equilibrium established?

• 0 seconds
• 1 second
• 5 seconds
• 10 seconds

What is the proper K_eq for the following reaction? 
   2 NO_(g)  +  O_2(g) ⇋ 2 NO_2(g)

• K = [NO₂]² / [NO]²[O₂]
• K =  [NO]²[O₂] / [NO₂]²
• K = [NO]²[O₂][NO₂]²
• K = 2[NO][O₂] / 2[NO₂]

Tags

NGSS.HS-PS1-6

What is the correct equilibrium expression for the following reaction:
2H₂O₂(aq) ⇋ 2H₂O(l) + O₂(g)

• [H₂O]²[O₂] / [H₂O₂]²
• [H₂O₂]² / [H₂O]²[O₂]
• [O₂] / [H₂O₂]²
• [H₂O]² / [H₂O₂]²

Tags

NGSS.HS-PS1-7

What factor would prevent equilibrium from being reached

• constant temperature
• closed system
• presence of both reactants and products 
• irreversible reaction

Tags

NGSS.HS-PS1-6

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.

An equilibrium constant with a large magnitude indicates…

• A very fast reaction
• More products at equilibrium
• More reactants at equilibrium
• nothing, without considering the stoichiometry of the reaction

Identify the incorrect statement about achieving equilibrium.

• achieved when product and reactant concentrations are equal

• achieved when forward and reverse reaction rates are same

• achieved when concentration of reactants is stable/constant

• achieved when concentration ratio of reactants to products becomes stable, thus fixing the equilibrium constant (equilibrium position)

Tags

NGSS.HS-PS1-7

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

  What is the correct equilibrium expression for the following equation
4CuO_(s)+CH_4(g)  ⇋  CO_2(g)+4Cu_(s) +2H₂O_(g)

• [CO_2(g)][Cu_(s)][2H₂O_(g)] _/ [CuO_(s)][CH_4(g)]
• [CO_2(g)][2H₂O_(g)] _/ [CH_4(g)]
• [CO_2(g)][H₂O_(g)]² _/ [CH_4(g)]
• [CO_2(g)][H₂O_(g)]² _/ [CH_4(g)][CuO_(s)]⁴

Tags

NGSS.HS-PS1-6