Question

The half life of N2O5 at
0°C is 24 minutes. How long will it take for sample of N2O5 to decay to 25% of its original concentration?
A) 24 minutes
B) 120 minutes
C) 72 minutes
D) 48 minutes
plz plz solve this...​

Answer 1

ANSWER

For a 1st order reaction,

t1/2= 0.693/k (k=rate constant)

Therefore, k = 0.693/t1/2 = 0.693/24= 0.0289 hr-1

kt= 2.303*log(a/(a-x)) {a= initial amount, a-x= amount left}

0.0289*96 = 2.303*log(10/(10-x))

log(10/(10-x))= 1.2

10/(10-x) = antilog1.2

10/(10-x) = 15.85

10 = 158.5-15.85x

15.85x = 148.5

x= 9.36g

a-x = 10-9.36= 0.63g

Hence, option 2 is correct

Answer 2

Go through the attachment

Hope it will helps you