# Thermodynamics first law closed system

1. Nov 12, 2013

### jordan2delta

1) A rigid walled tank 5m3 contains helium at 10 bar. The cylinder is heated from 10 °C to 50 ° C. What is the work done during the heating cycle.

2. Nov 12, 2013

### jordan2delta

how can determinate the work done during the heating cycle?
W=integral of pDV

which expression can I use to get the work done during the heating cycle?any advice?

1) A rigid walled tank 5m3 contains helium at 10 bar. The cylinder is heated from 10 °C to 50 ° C. What is the work done during the heating cycle.

3. Nov 12, 2013

### jordan2delta

2) An expanding gas storage vessel contains 5 m3 of methane at 1.1 bar. On a hot day the gas is heated from 20 °C to 35 °C. What work is done by the gas on its surroundings

expression to calculate the work by the gas on the surroundings?
knowing that V=5m^3
p=1.1bar
t1=20 degree Celsius
t2= 35 degree Celsius
t2=

4. Nov 12, 2013

### jordan2delta

3)One mole of CO2 is charged to a piston at 10 bar pressure 293K. The piston is allowed to expand to 4 times its volume isothermally. What work is done on the surroundings? The gas behaves ideally

A more complicated example using a polyatomic gas
Part1
– CO2 is charged at 2 bar to a piston at 298 K volume 0.5 m3. It is known to vary as polytonic gas PV2=C. The gas is allowed to expand isothermally to twice its volume what work is done by the system

Part 2
– A Spring force (5 kN/m extension) is added to retain the piston what work is done this time if the expansion is the same and how much work is done against the spring the piston area is 0.1 m2

please help me! I really need formulas to determinate work done by the system, and the work against the spring