Question

the gas in the piston is being heated, and the piston has moved upward. the observation will be summarized in a row of the incomplete table below.

row | name | observation | variables
1 | boyles law | volume increases when pressure decreases | ?
2 | charless law | ? | ?
3 | gay-lussacs law | ? | temperature, pressure
4 | combined gas law | ? | ?

what are the variables for this piston?

Explanation:

Identify the physical process

Using the Gas Laws knowledge point

The problem states: "The gas in the piston is being heated, and the piston has moved upward."

• Heating the gas increases its temperature (\(T\)).
• The upward movement of the piston increases the volume (\(V\)) of the gas.
• The piston is free to move, meaning the internal pressure remains constant and equal to the external pressure.
• The amount of gas (number of moles, \(n\)) inside the sealed piston remains constant.

Relate to the gas laws

Using the Gas Laws knowledge point

• The process involves changes in temperature (\(T\)) and volume (\(V\)) at constant pressure (\(P\)) and amount of gas (\(n\)).
• This relationship is described by Charles's law, which states that volume is directly proportional to absolute temperature (\(V \propto T\)) when pressure and amount of gas are held constant.
• Therefore, the variables changing in this specific piston experiment are temperature and volume.

Answer:

• temperature and volume (Correct answer)
• pressure and number of molecules
• volume and number of molecules
• temperature only