Equilibrium and acids and bases

Which is the correct equilibrium constant expression for the following reaction?

Fe₂O_3(s) + H_2(g) —> Fe_(s) + H₂O_(g)

• K = [H₂O]3 / [H₂]³

• K = [Fe₂O₃] [H₂]³ / [Fe]²[H₂O]³

• K = [Fe]²[H₂O]³ / [Fe_2O₃] [H₂]³

• K= [Fe] [H₂O] / [Fe₂O₃] [H₂]

• K = [H₂] / [H₂O]

The equilibrium between carbon dioxide gas and carbonic acid is very important in biology and environmental science. CO_2(g) + H₂O_(l) —> H₂CO3(aq)

Which one of the following is the correct equilibrium constant expression (Kc) for this reaction?

• Kc= 1/ [H₂CO₃]

• Kc= [CO₂]/ [H₂CO₃]

• Kc= [H₂CO₃] / [CO₂]

• Kc= [CO₂] [H₂O] / [H₂CO₃]

• Kc= [H₂CO₃] / [CO₂] [H₂O]

At 400 °C, K = 64 for the equilibrium H₂(_g) + I_{2 (g)}—> HI_(g). If 3.00 mol H₂ and 3.00 mol I₂ are introduced into an empty 4.0 L vessel, find the equilibrium concentration of HI at 400ºC.

• 0.15 M

• 2.4 M

• 4.8 M

• 5.8 M

• 36 M

Calculate Kc for the reaction HI_(g) —> H_2(g) + I_2(g) given that the concentrations of each species at equilibrium are as follows: [HI] = 0.85 mol/L, [I₂] = 0.60 mol/L, [H₂] = 0.27mol/L.

• 0.19

• 0.22

• 4.5

• 5.25

• 160

Calculate Kp for the reaction 2NOCl(g)  $\leftrightarrow$  2NO(g) + Cl2(g) at 400°C if Kc at 400°C for this reaction is 2.1 x10–2.

•   2.1 x10–2   

• 1.7 x 10–3  

• .70

• 1.2

•  3.8 x 10–4

For the reaction H₂(g) + I₂(g) --> 2HI(g), K_P = K_c.

• True

• False

A chemical reaction in which products can react to re-form reactants is known as a(n)

• reforming reaction

• reversible reaction.

• buffered reaction

• stoichiometric reaction.

For any reaction at chemical equilibrium, the concentrations of products and reactants

• are equal.

• change

• remain unchanged

• decrease

A very high value for K indicates that

• reactants are favored.

• products are favored.

• equilibrium is reached slowly.

• equilibrium has been reached

What does a pH scale do?

• Tells you if a substance is an acid.
• Tells you if a substance is a base.
• Measures the strength or weakness of an acid or base.
• All of these are true.