Question

Part A

The rate constant for a certain reaction is k = 6.50×10⁻³ s−1 . If the initial reactant concentration was 0.950 M, what will the concentration be after 10.0 minutes?

Express your answer with the appropriate units

Part B

A zero-order reaction has a constant rate of 3.90×10⁻⁴M/s. If after 80.0 seconds the concentration has dropped to 9.00×10⁻²M, what was the initial concentration?

Answer 1

The rate constant suggestes it is a frist order reaction for which is given by

ln [A] = ln [A]0 -kt

where [A] and [A]0 are concentration at any time t and initial concentration respectively. K is rate constant =6.5*10^-3 sec-1 and t is time (10 minutes =10*60=600 seconds)

ln[A]= ln[0.95] -6.5*10^-3*600=-3.95129

[A] = 0.01923M

b) for a zero order reaction   [A]0- [A] =kt where [A] and [A]0 are concentration at any time t and initial concentration respectively, k is rate constant 3.9*10^-4 M/s and t= 80 seconds [A] =9*10^-2M

[A]0= [A]+kt= 9*10^-2+80*3.9*10^-4 =0.1212M