# B Heat transferred into a closed system

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1. May 6, 2016

### Axe199

So i am making a simple demonstration of ideal gas law using a cylinder piston system, heating the system so the piston is pushed up, i wanted to calculate the heat transferred into the system, will it be Cp(Tf-Ti) or Cp(Tf-Ti)+ work done by the system ?

2. May 6, 2016

### Staff: Mentor

Using the first law of thermodynamics, how would you answer this question?

3. May 6, 2016

### abdo799

well using the first law Q-W=ΔU, Q will equal to to ΔU+ W but i dont know how to calculate ΔU

4. May 6, 2016

### Staff: Mentor

For one mole of an ideal gas, $\Delta U =C_v(T_f-T_i)$. Now what?

5. May 6, 2016

### abdo799

why use Cv not Cp the system has constant pressure and variable volume

6. May 6, 2016

### Staff: Mentor

The internal energy of an ideal gas is (a) a function of temperature only or (b) a function of temperature and volume (per unit mass)?

For constant pressure, what is the amount of work that is done?

Last edited: May 6, 2016