Carbonic acid, H2CO3(aq), is a chemical substance which plays an important role in controlling the pH of body fluids. In aqueous solution it produces HCO3–(aq) and CO32–(aq) as shown below.
H2CO3(aq) + H2O(l) → H3O+(aq) + HCO3– (aq)
HCO3–(aq) + H2O(l) → H3O+(aq) + CO32– (aq)
The overall reaction can be written as the sum of the two reactions:
H2CO3 (aq) + 2H2O(l) → 2H3O+(aq) + CO32-(aq)
The concentration of the following substances involved in the reaction are:
[H3O+(aq)] = a mol/L
[CO32–(aq)] = b mol/L
[H2CO3(aq)] = c mol/L
The equilibrium constant for the overall reaction is:
K = [H3O+]^2[CO32-]/[H2CO3]
Since the reaction is in equilibrium, the concentrations of the species involved will be constant. Therefore, we can write:
K = (a^2)(b)/(c)
where:
K is the equilibrium constant
a is the concentration of H3O+ in mol/L
b is the concentration of CO32- in mol/L
c is the concentration of H2CO3 in mol/L
are you sure?
Apologies for the incorrect response. Let me correct myself.
The equilibrium constant for the overall reaction can be determined by multiplying the equilibrium constants of the individual reactions.
The equilibrium constant for the first reaction is:
K1 = [HCO3-][H3O+]/[H2CO3]
The equilibrium constant for the second reaction is:
K2 = [CO32-][H3O+]/[HCO3-]
Multiplying the two equilibrium constants together gives:
K = K1 * K2
Substituting the given concentrations, we have:
K = [HCO3-][H3O+]/[H2CO3] * [CO32-][H3O+]/[HCO3-]
Simplifying, we get:
K = [H3O+]^2 * [CO32-]/[H2CO3]
So, the correct equilibrium constant for the overall reaction is:
K = [H3O+]^2 * [CO32-]/[H2CO3]
To determine the equilibrium constant for the overall reaction, we need to write the equilibrium expression based on the stoichiometry of the reaction.
The balanced overall reaction is:
H2CO3(aq) + 2H2O(l) → 2H3O+(aq) + CO32-(aq)
The equilibrium constant expression can be written as:
K = [H3O+]^2 * [CO32-] / [H2CO3]
According to the concentrations given in the question:
[H3O+] = a mol/L (concentration of H3O+)
[CO32-] = b mol/L (concentration of CO32-)
[H2CO3] = c mol/L (concentration of H2CO3)
Therefore, the equilibrium constant expression becomes:
K = (a^2 * b) / c
So, the equilibrium constant for the overall reaction is K = (a^2 * b) / c.