JEE Advanced levelOne or more correct optionsDifficulty 3 of 3ck163
Reaction 1 has Ea=40kJmol−1 and A=1010s−1; reaction 2 has Ea=80kJmol−1 and A=1015s−1. Use R=8.314Jmol−1K−1 and ln105=11.51. Which statements are correct?
AAbove 418 K reaction 2 is faster
BBelow 418 K reaction 1 is faster
CThe two rate constants are equal at 300 K
DThe two lnk against 1/T lines cross at about 418 K
Answer: A, B, D
Setting lnA1−E1/RT=lnA2−E2/RT gives T=Rln(A2/A1)E2−E1=8.314×11.5140000=418 K. Reaction 2 has the steeper line, so it is slower at low T and faster above the crossing. At 300 K k1/k2=10−5e40000/(8.314×300)=92.2=1.