alleryStart learning →For a gas phase decomposition, k is 1.66 L/mol/s at 650 K and 7.39 L/mol/s at 700 K. What is the activation energy?
AAbout 56,500 J/mol
BAbout 78,000 J/mol
CAbout 94,000 J/mol
DAbout 113,000 J/mol
Answer & Solution
Correct answer: D. About 113,000 J/mol
1. Use Ea = -R times (ln k2 minus ln k1) divided by (1/T2 minus 1/T1).
2. The ratio k2 over k1 is 7.39 divided by 1.66, which is 4.452.
3. The natural log of 4.452 is 1.4933, and that is the difference of the two logs.
4. The reciprocal temperatures are 1/700 K equal to 1.42857 x 10^-3 per K and 1/650 K equal to 1.53846 x 10^-3 per K.
5. Their difference is -1.0989 x 10^-4 per K.
6. So Ea = -8.314 times 1.4933 divided by -1.0989 x 10^-4, which is 1.13 x 10^5 J/mol.
7. Rounding an intermediate reciprocal temperature to two figures is what produces the smaller distractor values here.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 12 "Kinetics", section 12.5 Collision Theory_
Keep practising Kinetics
Browse all Kinetics questions for IMU CET, or explore more Chemistry topics.
Related questions
Which enzyme deficiency is described as the most common one in humans?Why are most catalytic converters preheated by an electric heater?Which catalyst coats the surface of most modern three way catalytic converters?Which international treaty began phasing out chemicals linked to ozone destruction?Which prize did Paul Crutzen, Mario Molina and Sherwood Rowland share for their work on ozNitric oxide takes part in the decomposition of ozone. Why is it called a catalyst?On a reaction diagram the reagents sit at 6 kJ and the transition state at 20 kJ. What is What effect does a catalyst have on the position of an equilibrium?