KCET · Chemistry · Chemical Kinetics

For a chemical reaction,
\( \mathrm{mA} \rightarrow \mathrm{xB} \), the rate law is \( r=k[\mathrm{~A}]^{2} \).
If the concentration of \( A \) is doubled, the reaction rate will be,

A Doubled
B Quadrupled
C Increases by \( 8 \) times
D Unchanged

Verified Solution

Answer & Solution

Correct Answer

(B) Quadrupled

Step-by-step Solution

Detailed explanation

For the reaction \(m A \rightarrow x B\)
The given rate law is \(R=k[A]^{2}\)
If conc. of \(\mathrm{A}\) is doubled, the new rate is
\(R^{\prime}=k[2 A]^{2}\)
\(R^{\prime}=4 k\left[A^{2}\right]\)
Hence, the new rate will be quadrupled to the original rate, that is, \(R^{\prime}=4 R\)

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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For a chemical reaction,\( \mathrm{mA} \rightarrow \mathrm{xB} \), the rate law is \( r=k[\mathrm{~A}]^{2} \).If the concentration of \( A \) is doubled, the reaction rate will be,

Step-by-step Solution

For a chemical reaction,
\( \mathrm{mA} \rightarrow \mathrm{xB} \), the rate law is \( r=k[\mathrm{~A}]^{2} \).
If the concentration of \( A \) is doubled, the reaction rate will be,