Chemistry · Chemical Equilibrium | MDCAT MCQ

Question

If the equilibrium expression of a reversible reaction is [C]²/[A][B].The balanced chemical equation should be

Options

A
C⇌A+B
B
2C⇌A+B
C
A+B⇌C
D
A+B⇌2C

Explanation

The correct balanced chemical equation is

A+B⇌2C

. This reflects the stoichiometry needed to yield the equilibrium expression [C]²/[A][B]. Each mole of A and B produces two moles of C, which is consistent with the squared term in the expression. The other options do not yield the correct relationship between the concentrations of reactants and products as stated in the equilibrium expression. For example,

C⇌A+B

would give a different equilibrium expression, and similarly for

2C⇌A+B

and

A+B⇌C

, which also do not satisfy the required form. This equation suggests that one mole of C decomposes into one mole of A and one mole of B. The equilibrium expression would be [A][B]/[C], which does not match the given expression. This equation indicates that two moles of C decompose into one mole of A and one mole of B. The equilibrium expression would be [A][B]/[C]², which is also not correct. This equation shows that one mole of A and one mole of B react to form one mole of C. The equilibrium expression would be [C]/[A][B], which is not the same as the given expression. This balanced equation indicates that one mole of A and one mole of B react to form two moles of C. The equilibrium expression is [C]²/[A][B], which matches the given expression, making this the correct option.