Question

# 8]] a) the number of moles of O2 in 56.4 L of O2 gas b) the...

8]] a) the number of moles of O2 in 56.4 L of O2 gas

b) the volume, in liters, occupied by 0.170 mole of He gas

1.24 If the partial pressures are oxygen 440 torr and helium 40 torr , what is the partial pressure (torr) of the nitrogen in the mixture?

1.25 . If the partial pressure of oxygen drops below 110 mmHg , passengers become drowsy. If this happens, oxygen masks are released. What is the total cabin pressure at which oxygen masks are dropped?

Since there is no information about Temperature and Pressure, it is assumed that O2 and He are at STP.

At STP, P = 1 atm , T = 273 K

8) a) It is assumed that O2 gas is at STP

At STP,

P = 1 atm

T = 273 K

Given that Volume of O2 gas V = 56.4 L

number of moles of O2 gas , n = ?

Ideal gas equation is

PV = nRT R = universal gas constant = 0.0821 L.atm/K/mol

n = PV/RT

= 1 atm x 56.4 L / ( 0.0821 L.atm/K/mol x 273 K)

= 2.52 moles

Therefore,

number of moles of O2 in 56.4 L of O2 gas = 2.52 moles

b)

It is assumed that He gas is at STP.

At STP,

P = 1 atm

T = 273 K

Given that number of moles of He gas, n = 0.17 moles

volume of He gas, V = ?

Ideal gas equation is

PV = nRT R = universal gas constant = 0.0821 L.atm/K/mol

V = nRT/P

= 0.17 moles x 0.0821 L.atm/K/mol x 273 K / 1 atm

= 3.81 L

Therefore,

volume occupied by 0.170 mole of He gas = 3.81 L

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