1. The half-life for the (first-order) radioactive decay of 14C is 5730 yr (it emits a β ray with an

Question

energy of 0.16 MeV). An archaeological sample contained wood that had only 72 percent of the 14C
found in living trees. What is its age?
I got 500years?

2. The temperature dependence of the acid-catalyzed hydrolysis of penicillin was investigated,
and the dependence of the rate constant on temperature is given below. What is the activation energy
and Arrhenius preexponential factor for this hydrolysis reaction?
Temperature (oC) k (s–1)
22.2 7.0 x 10–4
27.2 9.8 x 10–4
33.7 1.6 x 10–3
38.0 2.0 x 10–3

I found it to be 3.5........?

I'm pretty lost....I'd greatly appreciate any help!

Answer 1

.72=e^(-.692t/5730)

t== 5730/.692 ln .72 I don't get 500 years.

2)
I don't have time to solve it now, perhaps later.

ln rate=ln A - activationenergy/RT

You will need two points to find two unknowns, knowing T and rate.

Answer 2

see other post