Question

problem 3 of 28
a (blue) ⇌ b (red)
the equilibrium constant (k) for this reaction is 0.8. at which point does the reaction reach equilibrium?
before
after
a) b) c) d)

Explanation:

Step1: Recall equilibrium constant formula

The equilibrium constant $K = \frac{[B]}{[A]}$, where $[B]$ and $[A]$ are the molar - concentrations of $B$ and $A$ at equilibrium. Given $K = 0.8=\frac{4}{5}$, which means at equilibrium, the ratio of the number of $B$ molecules to $A$ molecules is $4:5$.

Step2: Analyze each option

Count the number of blue ($A$) and red ($B$) molecules in each of the "AFTER" boxes.

• In option A: Count the number of $A$ and $B$ molecules. Let the number of $A$ be $n_A$ and number of $B$ be $n_B$. If we assume each small square represents a unit of concentration. Calculate the ratio $\frac{n_B}{n_A}$.
• In option B: Do the same for option B.
• In option C: Do the same for option C.
• In option D: Do the same for option D.

After counting, we find that in option C, if we count the number of blue ($A$) and red ($B$) molecules, we get a ratio close to $\frac{4}{5}$.

Answer:

C