Question

A) A bubble of 5 moles of Argon gas (Monatomic) is submerged underwater, and undergoes a temperature increase of 25° C. How much heat was required in Joules?
J

B) 5 moles of Argon gas (Monatomic) undergoes a temperature increase of 25° C in a glass box with fixed volume? How much heat was required in Joules?

C) A heat engine is operating between 367 C and 37 C. If the engine extracted 100 MJ of energy from fuel, how many MJ of energy could be used as mechanical energy?

Answer 1

A) heat required = nCp*T

Cp for monoatomic gas = 5R/2

Q = 5*5*8.314*25 / 2

= 2598.13 J

B) since this is a constant volume process

Q = nCv*T

Cv for monoatomic gas = 3R/2

Q = 5*3*8.314*25 / 2

= 1558.88 J

C)efficieny = 1 - T(cold) / T(hot)

the temperatures are in kelvin

= 1 - (273 + 37) / ( 273 + 367)

= 0.515

= work done / heat supplied

0.515 = W/100

W = 0.515*100 = 51.5 MJ

so 51.5 MJ can be used as Mechanical energy