Respuesta :
Answer:
1.293 kg/m³
Explanation:
Density: this can be defined as the ratio of the mass of a body and its volume.
The S.I unit of density is kg/m³
D = m/v............................ Equation 1
D = density of air, m = mass of air, v = volume of air.
Note: Since the air is made up of nitrogen, oxygen and argon. the mass and volume of air will be the sum of the mass and sum of the volume of nitrogen, oxygen, and argon respectively.
(i) Mass of one mole of N₂ = 28 g
Therefore, mass of 0.78 mole of N₂ = 28×0.78 = 21.84 g.
(ii) Mass of one mole of O₂ = 32 g
Therefore, mass of 0.21 mole of O₂ = 32×0.21 = 6.72 g
(iii) Mass of one mole of Ar = 40 g
Therefore mass of 0.01 mole of Ar = 0.01×40 = 0.4 g
m = 21.84 + 6.72 + 0.4 = 28.96 g
Also Note: One mole of every gas at standard temperature and pressure = 22.4 dm³
Therefore,
(i) volume of 0.78 mole of N₂ = 22.4×0.78 = 17.47 dm³
(ii) volume of 0.21 mole of O₂ = 0.21×22.4 = 4.704 dm³
(iii) volume of 0.01 mole of Ar = 0.01×22.4 = 0.224 dm³
Therefore,
v = 17.47+4.704+0.224
v = 22.398 dm³
Substituting the value of v and m into equation 1
D = 28.96/22.398
D = 1.293 g/dm³
D = 1.293 kg/m³
Answer:
The density is 1.29g/L
Explanation:
Step 1: Data given
Mol fraction of N2 = 0.78
Mol fraction of O2 = 0.21
Mol fraction of Ar = 0.010
Molar mass N2 = 28 g/mol
Molar mass O2 = 32 g/mol
Molar mass of Ar = 39.95 g/mol
Volume = 22.4 Lat STP
Molar volume = 22.4mol/L at STP
Step 2: Calculate moles
Total moles of sample = 1.00 moles
N2 = 0.78 mol
O2 = 0.21 mol
Ar = 0.01 mol
Step 3: Calculate mass
Mass = moles * molar mass
Mass N2 = 0.78 mol * 28 g/mol = 21.84 grams
Mass O2 = 0.21 mol * 32 g/mol = 6.72 grams
Mass Ar = 0.01 mol * 39.95 g/mol = 0.3995 grams
Total mass in 1 mol of gas = 28.9595 grams
Step 4: Calculate density
Density = mass / volume
Density 28.9595 grams / 22.4 L
Density = 1.29 g/L
The density is 1.29g/L
