Question

Phosphine decomposes in a first order process.

a) If an initial concentration of 0.716 M PH₃ decreases to 0.0273 M in 165 seconds, what is the half-life?

ln[PH₃]_t = -kt + ln[PH₃]_o

b) How many half-lives have passed during this time?

t_TOTAL = nt_1/2

c) Using the 2ⁿ form of the first order decay equation, what was the original concentration of phosphine if 0.120 M remain after 2.00 minutes?

Q_t = Q_i/2ⁿ

Answer 1