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I've got these two questions. I think I've correctly worked them out however I'm currently stuck on the last part. How is density linked to mass and mols?

## Homework Statement

1 A gas cylinder contains 0.12 m3 of a gas at a pressure of 4545 kPa. What volume would it occupy if it was all released into a pressure of 101 kPa? Assume the temperature remains constant.

2 A car tyre of volume 1.0 * 10-2 m3 contains air at a pressure of 300 kPa and at a temperature of 17oC. The mass of one mole of air is 2.9 *10-2 kg. Assuming that the air behaves as an ideal gas, calculate;

i. the amount of air in moles,

ii. the mass of the air,

iii. the density of the air.

## Homework Equations

pV=k

pV=nRT

## The Attempt at a Solution

1) pV=k

4545kPa x 0.12m

^{3}=545.4

Therefore:

101Pa x V = 545.3

V = 5.4m

^{3}

2)i) Assuming ideal gas.

pV=nRT

n=[(4545x10

^{3}Pa)(1x10

^{-2}m

^{3})] / [(8.31Jmol

^{-1}K

^{-1})(290.15K)]

n=18.84995375mol

ii) mass of gas = 18.84995375mol x 2.9x10

^{-2}

=0.546648658

=0.547 (3dp) kg

iii) Please see above comments.

Thanks,