Given above is the concentration vs time plot for a dissociation reaction : A→ nB.
Based on the data of the initial phase of the reaction (initial 10 min ), the value of n is ____ .

Solution

Chemistry ma’am · 3 steps

Compare what A lost with what B gained in the same 10 minutes; that ratio is n.

1. Stoichiometry link. For A → nB, every 1 mol of A that reacts gives n mol of B. So in any time interval, n = Δ[B]/-Δ[A].
2. Read the graph. The falling curve is A: it drops from 0.05 M at t = 0 to 0.04 M at 10 min, a loss of 0.01 M. The rising curve is B: it climbs from 0 to 0.03 M in the same 10 min.

   n = (0.03 - 0)/(0.05 - 0.04) = 0.03/0.01 = 3

3. So. Each A gives three B, so n = 3, which is option (d).

The idea to keep. In a concentration vs time plot, the changes in reactant and product over the same interval are in the ratio of their coefficients. Always use changes, never the values left over.

Answer from the NTA final answer key. Solution by PrepWiser.