Question

1A. For a first order reaction, the rate will double if

a.      Concentration of a reactant is doubled

b.     Concentration of a product is doubled

c.      Concentration of a reactant is squared

d.     Temperature is raised two degrees

e.    2 moles of catalyst are added

1B.     For a second order decomposition reaction (one reactant), if the concentration of the reactant is tripled, the rate:

a.      Triples

b.     Increases nine-fold

c.      Decreases by one third

d.     Stays the same

Answer 1

1. Let A B so rate(r) = k[A] this is first order reaction.where k is the rate constant of first order reaction ..........(1)

if the concentration is double then rate(r') = k[2A] = 2k[A] = 2r ( from (1) )

so if the concentration is double then rate is also double in case of first order reaction.so (a) correct matches.

2. A+A B so rate(r) = k[A]² where k is rate constant of second order reaction..........(2)

if the concentration of the reactant is tripled, the rate(r') = k[3A]² = k 9[A]²

So rate(r') = 9 k[A]² using equation (2)

r' = 9 r

it increase nine fold as option (b) matches.