Question

# 1) A first order reaction has an activation energy of 66.6 kJ/mol and a frequency factor...

1) A first order reaction has an activation energy of 66.6 kJ/mol and a frequency factor (Arrhenius constant) of 8.78 x 1010 sec -1. Calculate the rate constant at 19 oC. Use 4 decimal places for your answer.

2) A first order reaction has a rate constant of 0.988 at 25 oC and 9.6 at 33 oC. Calculate the value of the activation energy in KILOJOULES (enter answer to one decimal place)

Arhenius equation is lnK= lnKo-Ea/RT

where Ea= activation energy= 66.6 Kj/mole= 66.6*1000J/mole, R= gas constant= 8.314 J/mole.K, T= 19+273= 292K

K0= frequency factor= 8.78*1010/sec

lnK= ln(8.78*1010)- 66.6*1000/(8.314*292)

K=0.1069/sec

when Arheius equation is written for two diffeent temperatures T1, T2 where rate constants are K1 and K2

ln (K2/K1)= (Ea/R)*(1/T1-1/T2)

T1= 25+273= 298K, K1= 0.988, T2= 33+273= 306K, K2= 9.6

hecne ln(9.6/0.988)= (Ea/8.314)*(1/298-1/306)

Ea= 215485 Joules= 215.48 KJ

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