Isothermal process involving changes in Volume and Pressure

[dbag123]

Homework Statement

Equipped diver is at the depth of 21 m, where the pressure is 2,1 bar. The diver breathes air that is pressurized to 2 bar. What would the final lung capacity be if the diver held their breath while ascending to the surface? diver lung capacity is 5.1 L and temperature is constant

Relevant Equations

p1v1=p2v2

P1 = 2 bar V1 = 5.1L P2= 1bar

V2 = V1P1/P2 = 10,2L, so the volume of gas would double?

or should the absolute pressure be taken into account

P1= 2bar (3bar absolute), V1=5.1L P2= 1 bar

V2 = 15,3L?

 

[Orodruin]

Homework Statement:: Equipped diver is at the depth of 21 m, where the pressure is 2,1 bar.

This is incorrect. Each 10 m adds roughly one bar. Since pressure at the surface is 1 bar, pressure at 21 m would be around 3.1 bar, not 2.1.

 

[dbag123]

but what about the solution? air in lungs 2bar. diver swims to surface where the pressure is 1bar, the lungs would expand from 5.1 to 10.2L. is it wrong?

 

[berkeman]

or should the absolute pressure be taken into account

but what about the solution? air in lungs 2bar. diver swims to surface where the pressure is 1bar, the lungs would expand from 5.1 to 10.2L. is it wrong?

Can you work the problem using absolute pressures? What do you get for a solution then?

 

[dbag123]

Can you work the problem using absolute pressures? What do you get for a solution then?

P1= 2 bar (3 bar absolute), V1=5.1L P2= 1 bar

V2 = 15,3L

the problem i am having is if the pressure of air in lungs (2 bar) is important or the pressure outside of the diver 3,1 bar(abs)