Year 12s: what will be the first way you research your future options? >>

Ideal gas equation n graph diff

Vadevalor

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Option 3 isnt correct cuz P proportional to T but why the graph shows constant?

Reply 1

Bradshaw

It's a graph of mass vs temp, not pressure vs temp.

But ..Read the qn

Original post by Vadevalor

But ..Read the qn

The pressure depends on the force being applied to the walls of the vessel. It goes up with temperature because the molecules have more energy. Remember the ideal gas law:

p = (nR/V)T

Above the indicated temperature, everything has been boiled, hence mass (and therefore n) is constant. The vessel has constant volume, so pressure varies linearly with temperature.

Reply 4

Vadevalor

Why isnt the pressure on the walls by the particles ( which is constant shown by graph to be constant after T) the same as pressure of the particles dictated by ideal gas equation? I know it should increase but that contradicts the graph data isnt it? Increased pressure of the vapour should increase pressure on the walls why is the graph linear after time t?

Qn says mass is determined by pressure

Reply 5

Bradshaw

It says that they work out the mass from the pressure measurements. This is not the same as saying that the two are directly linked.

In fact they are using the gas equation:
n=pV/RT. V and R are constants, we are varying T and measuring P.