Question Detail
Question
Nitric oxide reacts with chlorine to form nitrosyl chloride, NOCl. Use the following data to determine the rate equation for the reaction: 2NO + Cl₂ → 2NOCl. Data: Expt 1: [NO]=0.22, [Cl₂]=0.065, Rate=0.96 M/min; Expt 2: [NO]=0.66, [Cl₂]=0.065, Rate=8.6 M/min; Expt 3: [NO]=0.44, [Cl₂]=0.032, Rate=1.9 M/min.
Correct Answer
Option B is the correct answer.
Detailed Explanation
Compare Expt 1 and 2: [Cl₂] constant, [NO] triples, rate increases by factor of 8.96/0.96 ≈ 9, so order in NO is 2 (since 3² = 9). Compare Expt 1 and 3: [NO] doubles (0.22 to 0.44), [Cl₂] halves (0.065 to 0.032). Rate increases from 0.96 to 1.9 (factor ~2). The effect of NO doubling alone would be 4×; to get overall 2×, the Cl₂ change must reduce rate by 0.5×, so order in Cl₂ is 1. Rate = k[NO]²[Cl₂].
Hint
Determine the order by comparing experiments where one concentration changes at a time.