Reaction Rates and Order
Reaction Rate
Learning Objectives:
- State what rate of reaction is
- Identify observable changes to reactants or products for determining the rate of reaction
- Dtermine average rate of reaction
- Determine average rate of reaction at any given time from a graph
- Solve numerical problems involving average rate of reaction
- Solve numerical problems involving rate of reaction at any given time
The rate of reaction is the speed at which the reactants are converted into products in a chemical reaction.
As the reaction proceeds,- The amount of reactants decreases
- The amount of products increases
- Volume of gas liberated
- Time taken for precipitate formed
- Change of mass during reaction
- Color, temperature or pressure change
Solved Example: 9168-02
Rate constant for first order reaction is 6.93 $\times$ 10$^{-3}$s$^{-1}$. The half life of the reaction will be: (RPSC Grade II Science July 2019)
A. 10 s
B. 1000 s
C. 1 s
D. 100 s
Correct Answer: D
Solved Example: 9168-03
The rate of a chemical reaction doubles for every 10$^\circ$C rise of temperature. If the temperature is raised by 60$^\circ$C , then the rate of reaction increases by: (PNST July 2019 Shift II)
A. 10 times
B. 24 times
C. 64 times
D. 32 times
Correct Answer: C
Solved Example: 9168-04
For the reaction system \[2 NO(g) + O_2(g) \rightarrow 2NO_2 (g)\] the volume is suddenly reduced to half its value by increasing the pressure on it. lf the reaction is first order with respect to O$_2$, and second order with respect to NO, the rate of reaction will
A. Increase to four times of its initial value
B. Decrease to one-fourth of its initial value
C. Decrease to one-sight of its initial value
D. Increase to eight times of its initial value
Correct Answer: D
Reaction Order
Solved Example: 9168-01
In a batch reactor a homogenous reaction R → P occurs. The conversion of reactant R is 67% after to minutes and 80% after 20 minutes. Find the order of reaction up to nearest integer.
A. 1
B. 1.5
C. 2
D. 0
Correct Answer: C