BioPHYSICAL chemistry

2.14q=nCVΔT =(1.5 mol)(25 J/(Kmol))(35 K) =1.31 J

Since there is no work performed, the heat equals the change in

internal energy.

2.15

For an isothermal ideal gas, the change in internal energy is zero

when the temperature is fixed. Since the change in internal energy

is the sum of the heat and work, the heat is equal and opposite to

the work.

2.16 C 12 H 12 O 11 (solid) +12O 2 (gas) →12CO 2 (gas) +11H 2 O (liquid)

ΔH=12(−393.5 kJ mol−^1 ) +11(−285.8 kJ mol−^1 ) −1(−2222 kJ mol−^1 )

=−5644 kJ mol−^1

2.17 The temperature of the Earth is not uniform and so the overall

temperature increase represents a sum between decreasing and

increasing contributions.

2.18The amount of carbon dioxide in the atmosphere represents a balance

among the many different natural processes. With the introduction of

carbon dioxide by human activity, the balance is no longer main-

tained and the amount in the atmosphere has increased significantly.

2.19

or T 2 =1.03Tor 3%

2.20

Setting T 2 =1.1T 1 yields a 20% increase in the amount of solar

radiation.

CHAPTER 3

3.1 The entropy change of the system will always increase.

3.2 (a)

(b)

ΔS

q

T

.

()

==.

×

+

= −

25 10

273 200

52 8

4

J 1

K

JK

ΔS

q

T

.

()

==.

×

+

= −

25 10

273 20

85 3

4

J 1

K

JK

R

T

T

R

T

T

22 2 RR

4

1

4 1

2 1

4

1

4 1

2

1

==(. )^11 = → 146.^2 →=RR.

21121

T

SR A

d

T

R

T

es

4

2

2

1

4

1

2

=()constant ()^1 − →=^2

44

2

R^2

T

SR A

d

T

d

es d

4

2

2 2

4 1

2

2

1

()

()

=

−

constant →= 22 14 1

2

1

2 1

4

1

4

095

T 111

d

d

TT

(. )

==.

wnRT

V

V

nal

initial

=− ln^3 =−( 1 )( .8 314mol mmol) J/(KK

L

L

)( ) ln. 293kJ

30

10

=− 536

ANSWERS TO PROBLEMS 443

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