Question

a.) The rate constant for the reaction is 0.460 M–1·s–1 at 200 °C. A--> products. If the initial concentration of A is 0.00680 M. what is the concentration after 315 s?
b.)The rate constant for this zero-order reaction is 0.0190 M·s–1 at 300 °C. A--> products. How long (in seconds) would it take for the concentration of A to decrease from 0.800 M to 0.240 M?
c.)The rate constant for this second-order reaction is 0.520 M–1·s–1 at 300 °C. A--> products .How long (in seconds) would it take for the concentration of A to decrease from 0.630 M to 0.390 M?
d.)The rate constant for this first-order reaction is 0.970 s–1 at 400 °C. A--> products. How long (in seconds) would it take for the concentration of A to decrease from 0.840 M to 0.210 M?

Answer 1

Equations and importants tips

1) Order zero reactions.

Units of k=M/s

2)First order reactions

k units= s^-1

3) Second order Reactions

k units= M^-1.s^-1

PART A

the statement does not indicate which is the order of the reaction, but for the units of the rate constant (M^-1.s^-1), we can conclude that reaction is of second order. For calculus use equation for second order reactions

After 315s concentration is 3,42.10^-3M

PART B

Rate=k=0,0190M/s

when concentration decrease from 0,800M to 0,240M involves a change of 0,56M

Would take 29,5s for the concentration of A decreases of 0,800M a 0,240M.

PART C

t=1,88s

Would take 1,88s for the concentration of A decreases of 0,630M a 0,390M.

PART D

t=1,43s

Would take 1,43s for the concentration of A decreases of 0,840M a 0,210M.