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(1) The observed half life for this reaction when the starting concentration is

ID: 556973 • Letter: #

Question

(1)
The observed half life for this reaction when the starting concentration is 5.25×10-3 M is s and when the starting concentration is 2.63×10-3 M is___ s.

(2)
The average rate of disappearance of NH3 from t = 0 s to t = 998 s is  M s-1.

(3)
The average rate of disappearance of NH3 from t = 998 s to t = 1.50×103 s is  M s-1.

(4)
Based on these data, the rate constant for this _______zerofirstsecond order reaction is M s-1.

[NH3], M 5.25×10-3 2.63×10-3 1.32×10-3 6.60×10-4 seconds 0 998 1.50×103 1.75×103

Explanation / Answer

Q1

half life from 5.25*10^-3 to 2.63*10^-3

t = 998 seconds required

Q2.

average rate of reaciton for NH3

dC/dt = (2.63*10^-3 - 5.25*10^-3)/(998-0) = -0.00000262 M/s

Q3

the rate from 998s to 1.5*103

dC/dt = (Cf-Ci)/(tf-ti) = (1.32*10^-3 - 2.63*10^-3)/(1500-998) = -0.00000260 M/s

Q4

based on this data

the rate will NOT change as concentration changes

therefore, this must be ZERO order

with k = constnat value or

RAte = k

Rate = k = 0.00000260 M/s