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Please help me with this problem.

A Volume – Temperature diagram was obtained when a gas was heated at a constant pressure. During the heating process from state 1 to state 2 how does its mass vary?

Sometimes the diagram may not clear, so I will try to describe how it looks like. It is a straight line graph with an inclination of around 30 degrees. It has a positive slope. The volume is along the Y axis and the temperature is along the X axis.

I solved it the following way:

From the graph it is clear that at any point on the graph V/T < 1

But according to gas law,

PV = wRT/m

Where w = mass of gas and m = Molecular weight of gas

i.e. V/T proportional to w ( Since P is constant)

i.e. w < 1

Hence the mass of the gas decreases. Though it agrees with the answer in my book, I don’t know whether it is right. Please say whether its right or not?

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# Homework Help: Heating a gas at constant pressure

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