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1)You have a flask of liquid nitrogen at a temperature of -243°C. You then heat

ID: 1329852 • Letter: 1

Question

1)You have a flask of liquid nitrogen at a temperature of -243°C. You then heat the nitrogen until its temperature is doubled. What is the new temperature?

a)-486°C
b) -213°C
c)486°C
d)None of the above

2) An ideal gas in a balloon is kept in thermal equilibrium with its constant-temperature surroundings. How much work is done if the pressure is slowly reduced and the balloon expands to five times its original size? The balloon initially has a pressure of 815.0 Pa and has a volume of 0.70 m3.

-8.0 J
       -920 J
       -1,000 J
       -2,900 J

Explanation / Answer

1)
b) -213 degrees celsius

T1 = -243 + 273 = 30 k

T2 = 2*T1

= 2*30

= 60 k

= 60 - 273

= -213 degrees celsius

2) 920 J

Workdone in an isolthermal process, W = n*R*T*ln(V2/V1)

= P1*V1*ln(V2/V1)

= 815*0.7*ln(5)

= 920 J