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## Homework Statement

I need some help on these problems, i got most of the other problems right, but these ones im not sure what to do with. I dont even know if those are the right equations for it. Someone please help.

1. A cylinder-and-piston containing an ideal gas is placed in contact a thermal reservoir. The volume of the gas is very slowly changed from 50 liters to 12 liters as 50 J of work is done on it by an external agency. Determine the change in the internal energy of the gas.

The answer is in Joules

1.2. Determine the change in the amount of heat flowing into or out of the system. (For reference, a negative value of heat means it is flowing out of the system.)

the answer is in Joules

2. A gas in a thin plastic bag at atmospheric presure receives 10480 J of heat and, in the process, puffs up the bag, increasing its volume by 0.90 m3. By how much is the internal energy of the gas altered?

the answer is in kJ

3. Heat is added to 4.00 m3 of helium gas in an expandable chamber that thereupon increases its volume by 2.00 m3. If in the process 2.22 kJ of work are done by the gas, what was its original pressure?

the answer is in kPa

## Homework Equations

change in energy=W

change in energy=W+Q

change in energy=W+Q+Em

## The Attempt at a Solution

1. (50-12)+50

1.2. 88-50

2.(10480)(.9)

3.????

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