BioPHYSICAL chemistry

7.6 They are both equal to 0.05 M.

7.7 [B]/[C] =10 and [B] +[C] =0.1 M

10[C] +[C] =11[C] =0.1 M →[C] =0.009 M and [B] =0.09

7.8 (a)

(b) =−(2.0 M−^1 s−^1 )(0.1 M)(0.1 M) =−0.02 Ms−^1

=−(2.0 M−^1 s−^1 )(0.1 M)(0.1 M) =−0.02 Ms−^1

=(2.0 M−^1 s−^1 )(0.1 M)(0.1 M) −(1.0 s−^1 )(0.1 M)

+(5.0 s−^1 )(0.1 M) =0.42 Ms−^1

=(1.0 s−^1 )(0.1 M) −(5.0 s−^1 )(0.1 M) =−0.40 Ms−^1

(c) At equilibrium the concentrations of A and B are zero since the

reactions are irreversible. The sum of the concentrations must

be equal to 0.4 M and the ratio of the amounts of C and D is

given by the ratio of the two rate constants:

[C] +[D] =[C] +0.2[C] =0.4 M →[C] =1/3 M

[D] =0.2[C] =1/15 M

7.9

7.10 (a)

(b)

(c) Since the reaction is irreversible, the final concentration of A is

zero and that of B is 0.2 M.

dB

d

As M Ms

[]

[] ( )(. ).

t

=+kf =101 01−−^11 =

dA

d

AsM Ms

[]

[] ( )(. ).

t

=−kf =− 101 −−^11 =− 01

dA

d

A

dB

d

A

[]

[]

[]

[]

t

k

t

=−ff=+k

AAekt. ek s k

() ln.

=→= 0 −− 05 10 =−

05

10

Mor

s

=0 0693. s−^1

K

k

k

f

b

[]

[]

===→=.[].[]

D

C

(^2) D C and
2

02 02 [[] [ ] .CD+= 04 M

dD

d

[]

t

dC

d

[]

t

dB

d

[]

t

dA

d

[]

t

dC

d

AB C D

dD

d

[]

[][] [] []

[]

t

kkk

ffbt

=−+ 122 ==−kkfb 22 []CD[ ]

dA

d

AB

dB

d

AB

[]

[][]

[]

[][]

t

k

t

=−ff 11 =−k

450 ANSWERS TO PROBLEMS

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