In the equilibrium system CH3COOH(aq) + H2O(l) —> — H3O+ CH3COO-(aq)

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Which species is present in the highest concentrations at equilibrium?
A. CH3COOH
B. H3O
C. CH3COO-
D. Equal concentrations of CH3COOH, H3O+, And CH3COO- are present

Is A correct?

Yes, A is correct but do you know WHY it is correct or are you guessing?

hi

To determine which species is present in the highest concentrations at equilibrium, we need to examine the equilibrium expression for the reaction. The equilibrium expression describes the relationship between the concentrations of the reactants and products at equilibrium.

The equilibrium expression for the given reaction is:
Kc = [H3O+][CH3COO-] / [CH3COOH]

In this case, Kc is the equilibrium constant, and the concentrations of H3O+, CH3COO-, and CH3COOH are denoted in square brackets.

The equilibrium constant tells us the ratio of product concentrations to reactant concentrations at equilibrium. When the equilibrium constant is large, it means that the products are favored at equilibrium.

In this case, since the equilibrium expression includes both the product concentrations ([H3O+][CH3COO-]) and the reactant concentration ([CH3COOH]), we need to compare the value of Kc to determine which species is present in the highest concentration.

If Kc is large, it means that the product concentrations are much higher than the reactant concentration, and thus the species on the product side will be present in the highest concentrations.

If Kc is small, it means that the reactant concentration is much higher than the product concentrations, and thus the species on the reactant side will be present in the highest concentrations.

If Kc is approximately equal to 1, it means that the reactant and product concentrations are roughly similar, and the species present in the highest concentrations will depend on the initial conditions.

Therefore, we need to know the value of Kc to determine which species is present in the highest concentrations at equilibrium.

CH3COOH = HAc

HAc is a weak acid; therefore, it has an ionization constant, Ka. Look up that Ka value, write the Ka expression, and assuming a value of, say, 0.1M or HAc initially, you can calculate the three species and know the answer.
.........HAc + H2O <==> H3O^+ + Ac^-
I........0.1.............0.......0
C........-x..............x.......x
E......0.1-x.............x.......x

Where I is initial, C is change, and E is equilibrium.

Post your work if you get stuck.