• Skip to main content
  • Skip to secondary menu
  • Skip to primary sidebar
  • Skip to footer
  • NCERT Solutions
    • NCERT Books
  • Class 10
  • Class 9
  • Class 8
  • Class 7
  • Class 6
  • Class 11
  • Class 12
  • MCQ Questions
    • CBSE MCQ

Learn Insta

RD Sharma Solutions , RS Aggarwal Solutions and NCERT Solutions

  • Extra Questions
  • CBSE Notes
  • RD Sharma Solutions
    • RD Sharma Class 12 Solutions
    • RD Sharma Class 11 Solutions
    • RD Sharma Class 10 Solutions
    • RD Sharma Class 9 Solutions
    • RD Sharma Class 8 Solutions
  • RS Aggarwal Solutions
    • RS Aggarwal Solutions Class 10
    • RS Aggarwal Solutions Class 9
    • RS Aggarwal Solutions Class 8
    • RS Aggarwal Solutions Class 7
    • RS Aggarwal Solutions Class 6
  • ML Aggarwal Solutions
    • ML Aggarwal Class 10 Solutions
    • ML Aggarwal Class 9 Solutions
    • ML Aggarwal Class 8 Solutions
    • ML Aggarwal Class 7 Solutions
    • ML Aggarwal Class 6 Solutions
  • English Grammar
    • Words with Letters
    • English Summaries
    • Unseen Passages

Arrhenius Equation – The Effect of Temperature on Reaction Rate

July 1, 2021 by Prasanna

Find free online Chemistry Topics covering a broad range of concepts from research institutes around the world.

Arrhenius Equation – The Effect of Temperature on Reaction Rate

Generally, the rate of a reaction increase with increasing temperature. However, there are very few exceptions. The magnitude of this increase in rate is different for different reactions. As a rough rule, for many reactions near room temperature, reaction rate tends to double when the temperature is increased by 10°C.

A large number of reactions are known which do not take place at room temperature but occur readily at higher temperatures. Example: Reaction between H2 and O2 to form H2O takes place only when an electric spark is passed.

Arrhenius suggested that the rates of most reactions vary with temperature in such a way that the rate constant is directly proportional to e-(Ea/RT) and he proposed a relation between the rate constant and temperature.

k = Ae-(Ea/RT) …………. (1)

Where A the frequency factor,
R the gas constant,
Ea the activation energy of the reaction and,

T the absolute temperature (in K)

The frequency factor (A) is related to the frequency of collisions (number of collisions per second) between the reactant molecules. The factor A does not vary significantly with temperature and hence it may be taken as a constant.

Ea is the activation energy of the reaction, which Arrhenius considered as the minimum energy that a molecule must have to posses to react.

Taking logarithm on both side of the equation (1)

Arrhenius Equation - The Effect of Temperature on Reaction Rate img 1

y = c + mx

The above equation is of the form of a straight line y = mx + c.

A plot of ln k Vs 1/T gives a straight line with a negative slope – \(\frac{\mathrm{E}_{\mathrm{a}}}{\mathrm{R}}\) line with a negative slope –\(\frac{\mathrm{E}_{\mathrm{a}}}{\mathrm{R}}\). If the rate constant for a reaction at two different temperatures is known, we can calculate the activation energy as follows.

At temperature T = T1; the rate constant k = k1

Arrhenius Equation - The Effect of Temperature on Reaction Rate img 2

This equation can be used to caluculate Ea from rate constants K1 and k2 at temperatures
T1 and T2.

Example 1

The rate constant of a reaction at 400 and 200K are 0.04 and 0.02 s-1 respectively. Caluculate the value of activation energy.
Solution:
According to Arrhenius equation
Arrhenius Equation - The Effect of Temperature on Reaction Rate img 3
Ea = log(2) × 2.303 × 8.314 JK-1mol-1 × 400K
Ea = 2.305 J mol-1

Example 2

Rate constant k of a reaction varies with temperature T according to the following Arrhenius equation log k = log A – \(\frac{\mathrm{E}_{\mathrm{a}}}{2.303 \mathrm{R}}\)(\(\frac{1}{T}\)) Where Ea is the activation energy. When a graph is plotted for log K Vs \(\frac{1}{T}\) a straight line with a slope of – 4000k is obtained. Caluculate the activation energy.
Solution:
log k = logA – \(\frac{\mathrm{E}_{\mathrm{a}}}{2.303 \mathrm{R}}\)(\(\frac{1}{T}\))
y = c + mx
m = – \(\frac{\mathrm{E}_{\mathrm{a}}}{2.303 \mathrm{R}}\)
Ea = – 2.303 R m
Ea = – 2.303 × 8.314 JK-1 mol-1 × (-4000K)
Ea = 76, 589 J mol-1
Ea = 76.589 kJ mol-1

Filed Under: Chemistry

Primary Sidebar

  • Maths NCERT Solutions
  • Science NCERT Solutions
  • Social Science NCERT Solutions
  • English NCERT Solutions
  • Hindi NCERT Solutions
  • Physics NCERT Solutions
  • Chemistry NCERT Solutions
  • Biology NCERT Solutions
RS Aggarwal Solutions RD Sharma Solutions
RS Aggarwal Class 10 RD Sharma Class 10
RS Aggarwal Class 9 RD Sharma Class 9
RS Aggarwal Class 8 RD Sharma Class 8
RS Aggarwal Class 7 RD Sharma Class 11
RS Aggarwal Class 6 RD Sharma Class 12

Recent Posts

  • Mechanical Properties of Solids Class 11 Important Extra Questions Physics Chapter 9
  • Selina Concise Mathematics Class 10 ICSE Solutions Chapter 8 Remainder and Factor Theorems Ex 8A
  • MCQ Questions for Class 9 Maths Chapter 2 Polynomials with Answers
  • MCQ Questions for Class 7 Maths Chapter 2 Fractions and Decimals with Answers
  • English Grammar for Class 6, 7, 8, 9, 10, 11 and 12
  • Unscramble Words With Letters | Make Words with These Letters
  • Fractions and Decimals Class 7 Notes Maths Chapter 2
  • MCQ Questions for Class 6 Maths Chapter 8 Decimals with Answers
  • MCQ Questions for Class 6 Maths Chapter 1 Knowing Our Numbers with Answers
  • RD Sharma Class 10 Solutions Chapter 12 Heights and Distances Ex 12.1
DMCA.com Protection Status

Footer

CBSE Library
NCERT Library
NCERT Solutions for Class 12
NCERT Solutions for Class 11
NCERT Solutions for Class 10
NCERT Solutions for Class 9
NCERT Solutions for Class 8
NCERT Solutions for Class 7
NCERT Solutions for Class 6
ML Aggarwal Class 10 ICSE Solutions
Concise Mathematics Class 10 ICSE Solutions
CBSE Sample Papers
cbse
ncert
English Summaries
English Grammar
Biology Topics
Microbiology Topics
Chemistry Topics
Like us on Facebook Follow us on Twitter
Watch Youtube Videos Follow us on Google Plus
Follow us on Pinterest Follow us on Tumblr
Percentage Calculator

Copyright © 2022 Learn Insta