Chemical EquilibriummediumMCQ SINGLE⭐ Must-Do

A reaction has an equilibrium constant . If the initial concentration of all four species is artificChemical Equilibrium Chemistry Question

Question

A reaction $A + B \rightleftharpoons C + D$ has an equilibrium constant $K_c = 100$. If the initial concentration of all four species is artificially set to $1\text{ M}$ each, what will be the equilibrium concentration of $D$?

Answer: B

💡 Solution & Explanation

Initially $Q_c = \frac{(1)(1)}{(1)(1)} = 1$. Since $Q_c < K_c$ ($1 < 100$), the reaction proceeds forward. Let $x$ moles react. At equilibrium: $[A] = 1-x$, $[B] = 1-x$, $[C] = 1+x$, $[D] = 1+x$. $K_c = \frac{(1+x)^2}{(1-x)^2} = 100$. Taking the square root: $\frac{1+x}{1-x} = 10 \Rightarrow 1+x = 10 - 10x \Rightarrow 11x = 9 \Rightarrow x = 0.818$. Thus, $[D] = 1 + x = 1.818\text{ M}$.

💬
Still have doubts about this question?
Send it to our AI chemistry tutor on WhatsApp — gets answered in minutes
Ask on WhatsApp →

Practice 22,000+ questions like this

AI-adaptive practice, video lectures, and full IChO (Chemistry Olympiad) content — all in one place.

JEE Advanced · JEE Mains · NEET · IChO · AP Chemistry