A sample of nitrogen gas kept in a container of volume 216 L

A sample of nitrogen gas kept in a container of volume 2.16 L and at a temperature of 21°C exerts a pressure of 4.67 atm. Calculate the number of moles of gas present. mol

Solution

1)
Given:
P = 4.67 atm
V = 2.16 L
T = 21.0 oC
= (21.0+273) K
= 294 K

find number of moles using:
P * V = n*R*T
4.67 atm * 2.16 L = n * 0.08206 atm.L/mol.K * 294 K
n = 0.418 mol
Answer: 0.418 mol

2)
Given:
V = 32.2 L
n = 7.10 mol
T = 62.0 oC
= (62.0+273) K
= 335 K

use:
P * V = n*R*T
P * 32.2 L = 7.1 mol* 0.08206 atm.L/mol.K * 335 K
P = 6.06 atm
Answer: 6.06 atm

3)
P= 703.0 mm Hg
= (703.0/760) atm
= 0.925 atm
T= 45.0 oC
= (45.0+273) K
= 318 K

Molar mass of HBr,
MM = 1*MM(H) + 1*MM(Br)
= 1*1.008 + 1*79.9
= 80.908 g/mol

Lets derive the equation to be used
use:
p*V=n*R*T
p*V=(mass/molar mass)*R*T
p*molar mass=(mass/V)*R*T
p*molar mass=density*R*T

Put Values:
0.925 atm *80.908 g/mol = density * 0.08206 atm.L/mol.K *318.0 K
density = 2.87 g/L
Answer: 2.87 g/L

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