Chems101 experiment 7

Experiment 8: DETERMINING THE MOLAR MASS OF A GAS
Name : Musherah Moqbel Ali
Group number: 2
ID:
202002276
Sec:
18
Aim : the aim of this experiment is to determine the molar mass and density of a gas
using ideal gas law
1- Mass of flask filled with air
m1 = 36.0413
2- Mass of flask filled with gas
m2
g
= 36.1146 g
3- Mass of flask filled with water m3 = 139.1000 g
4- Room temperature = 23°C + 273 = 296 K
5 – Atmospheric pressure = 760 mmHg = 1 atm
6- Density of air under conditions of experiment = 0.00116 g / cm3
7- Mass of water = m3 – m1 = 139.1000 – 36.0413
= 103.0587 g
8- Density of water = 1.0 g / cm3
9- Volume of water = mH2O / dH2O = step 7 / step 8 =
10- V.H2O = V. flask = V.gas = V. air = 𝟏𝟎𝟑. 𝟎𝟓𝟖𝟕
𝟏𝟎𝟑.𝟎𝟓𝟖𝟕
𝟏.𝟎
= 𝟏𝟎𝟑. 𝟎𝟓𝟖𝟕 cm3
cm3
11- Mass of air m air = d air x Vair =step 6 x step 10 =
𝟎. 𝟎𝟎𝟏𝟏𝟔 × 𝟏𝟎𝟑. 𝟎𝟓𝟖𝟕 = 𝟎. 𝟏𝟏𝟗 g
12- Mass of empty flask = m1 – m air = step 1 – step 11 =
36.0413 – 𝟎. 𝟏𝟏𝟗 = 35.922 g
13- Mass of gas = m2 – m flask = step 2 – step 12 = 36.1146 – 35.922 = 0.192 g
14- Molar mass of a gas = m .gas x R x T / P x V
15- MM = step. 13 g x (0.0821 L .atm / K.mol ) x 296 K
1atm x step. 10 x 10-3 L
𝟎.𝟏𝟗𝟐 × 𝟎.𝟎𝟖𝟐𝟏 × 𝟐𝟗𝟔
16 – MM of the gas = 𝟏 × (𝟏𝟎𝟑.𝟎𝟓𝟖𝟕 × 𝟏𝟎−𝟑 ) = 45.2 g / mol
17 – The gas is CO2
18- The theoretical Molar Mass from periodic table = 44.0 g / mol
19- % Error = (Actual MM – Theoretical MM ) / Theoretical MM x 100 =
𝟒𝟓.𝟐−𝟒𝟒.𝟎
𝟒𝟒.𝟎
× 𝟏𝟎𝟎 = 𝟐. 𝟕 %
Conclusion :
At the end of the experiment, the molar mass and density of the gas was found and
the molar mass equaled 45.2 g/mol, and then from the molar mass, it was concluded
that the gas is CO2 because the molar mass of the gas which was calculated, was the
nearest to the molar mass of CO2 .And from the periodic table, the theoretical molar
mass of CO2 was found and equaled 44.0 g/mol , then the percentage error was
calculated and it was equal to 𝟐. 𝟕 % .
…