3 The conversion of cyclobutane to ethylene C4H8 g 2C2H4 g i

3. The conversion of cyclobutane to ethylene C4H8 (g) 2C2H4 (g) is a first order reaction with a half-life of 17 minutes. If 1.2 mol of cyclobutane is palced in 1 2.00L reaction vessel at 800K, what will its concentration be after 45 min? Determine how long it will take for 75% of eoriginal cyclobutane sample to be consumed. Nk

Solution

1) first order kinetics

k1 = (1/t)ln(a0/a)

a0 = initial concentration = 1.2/12 = 0.1 M

a = concentration remains after 45 min = x M

t = 45 min

K1 = 0.693/t1/2

   = 0.693/17

   = 0.0408 min-1

0.0408 = (1/45)ln(0.1/x)

x = 0.016 M

2)

k1 = (1/t)ln(a0/a)

a0 = initial concentration = 100%

a = concentration remains after 45 min = 100-75 = 25%

t = x min

0.0408 = (1/t)ln(100/75)

t = 7.05 min