Question

steel diving canisters can withstand internal pressures of 300.0 atm, but for safety are regulated to working limits of 220 - 250 atm. what is the pressure exerted on the walls of the diving cylinder which has a capacity of 6.0 L and contains 250.0 g of oxygen and 500.0g of Nitrogen at the 25°C?

Is it corrected to use The Ideal Gas Law? Also as there are two molar mass provided, is it correct to add them together (after the molar mass conversion) or to multiply?

Can I please have the working out.

Thanks in advance.

Answer 1

Molar mass of oxygen (O₂) = 16*2 = 32g

Given mass of oxygen =250g

Moles = Given mass/Molar mass

Moles of oxygen = 250/32 = 7.81

Mass of nitrogen (N₂) = 14*2 = 28g

Given mass of nitrogen = 500g

Moles of nitrogen = 500/28 =17.86

Now apply ideal gas equation -

PV = nRT

P = Pressure exerted by the gases

V = Volume of the container = 6.0L

n = Total number of moles of gases present = 7.81 + 17.86 =25.67

R = Gas constant = 0.082 L atm K^-1 mol^-1

T = temperature = 25^oC = (273 + 25)K = 298K

P*6 = 25.67*0.082*298 =104.54atm

Pressure exerted on the walls of container by oxygen and nitrogen is 104.54atm.

For the two gases given you add their number of moles not the molar masses.