6. Which of the following chemical reactions is most likely to have the largest equilibrium constant K?
CH3COO- (aq) + H2O(l) = CH3COOH(aq) + OH-(aq)
HCl(aq) + H2O(l) = H3O+(aq) + Cl-(aq)
CH3COOH(aq) + H2O(l) = CH3COO- (aq) + H3O+(aq)
H3PO4(aq) + NH3(aq) = H2PO4-(aq) + NH4+(aq)
B. HCl(aq) + H2O(l) = H3O+(aq) + Cl-(aq)
The equilibrium constant, K, is a measure of the extent to which a chemical reaction proceeds to form products. The larger the value of K, the greater the extent of product formation.
To determine which of the given reactions is most likely to have the largest equilibrium constant, we can compare the strengths of the acids and bases involved. Acids and bases that are stronger tend to form products to a greater extent, resulting in a larger equilibrium constant.
In the given reactions, HCl and H3PO4 are both strong acids, while CH3COOH is a weak acid. NH3 is a weak base, while OH- is a strong base.
Comparing the reactions:
1. CH3COO- (aq) + H2O(l) = CH3COOH(aq) + OH-(aq): This is a weak acid-strong base reaction, which tends to have a moderate equilibrium constant.
2. HCl(aq) + H2O(l) = H3O+(aq) + Cl-(aq): This is a strong acid-strong base reaction, which tends to have a large equilibrium constant.
3. CH3COOH(aq) + H2O(l) = CH3COO- (aq) + H3O+(aq): This is a weak acid-strong acid reaction, which tends to have a moderate equilibrium constant.
4. H3PO4(aq) + NH3(aq) = H2PO4-(aq) + NH4+(aq): This is a weak acid-weak base reaction, which tends to have a small equilibrium constant.
Based on the strengths of the acids and bases involved, the reaction with the largest equilibrium constant, K, is:
HCl(aq) + H2O(l) = H3O+(aq) + Cl-(aq)
To determine which of the given chemical reactions is most likely to have the largest equilibrium constant, we need to analyze the reaction equation and consider the factors that can influence the equilibrium constant.
The equilibrium constant, K, is a measure of the extent to which a chemical reaction proceeds towards completion. It relates the concentrations of the products to the concentrations of the reactants at equilibrium.
In general, a larger equilibrium constant indicates a greater concentration of products compared to reactants at equilibrium, suggesting that the reaction goes to completion.
To calculate the equilibrium constant for a reaction, you need to know the balanced chemical equation and the concentrations of the reactants and products at equilibrium.
Let's analyze each reaction and consider the factors that can affect the equilibrium constant:
1. CH3COO- (aq) + H2O(l) = CH3COOH (aq) + OH- (aq):
In this reaction, water reacts with acetate ion to produce acetic acid and hydroxide ion. This is an example of a hydrolysis reaction of a salt. The concentration of hydroxide ions (OH-) would depend on the concentration of water, and hence the equilibrium constant will not be very high.
2. HCl (aq) + H2O (l) = H3O+ (aq) + Cl- (aq):
This is the reaction of hydrochloric acid with water to form hydronium ion and chloride ion. Hydronium ion concentration is relatively high in water due to the strong acid HCl. Therefore, this reaction is likely to have a relatively large equilibrium constant.
3. CH3COOH (aq) + H2O (l) = CH3COO- (aq) + H3O+ (aq):
This reaction involves the ionization of acetic acid in water, leading to acetate ion and hydronium ion formation. The concentration of hydronium ions (H3O+) depends on the acidity of acetic acid, which is relatively weak. Consequently, the equilibrium constant for this reaction is likely to be lower compared to the reaction in which a stronger acid is involved.
4. H3PO4 (aq) + NH3 (aq) = H2PO4- (aq) + NH4+ (aq):
This reaction involves the reaction of phosphoric acid and ammonia to form dihydrogen phosphate ion and ammonium ion. The equilibrium constant depends on the extent to which H3PO4 and NH3 react. Since phosphoric acid is a stronger acid compared to acetic acid, the equilibrium constant is likely to be relatively large.
Based on the considerations above, the second reaction, HCl (aq) + H2O (l) = H3O+ (aq) + Cl- (aq), is most likely to have the largest equilibrium constant, K, among the given reactions.