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Using Graham's Law of Diffusion, determine the molar mass of an unknown gas if ethane (C2H6) diffuses at a rate of 3.6 imes 10⁻⁶ mol/h and the unknown gas diffuses at 1.3 imes 10⁻⁶ mol/h?
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2 partsStep-by-step solution
6 stepsStep 1: Calculate the molar mass of ethane ().
The molar mass of carbon (C) is approximately 12.01 g/mol.
The molar mass of hydrogen (H) is approximately 1.008 g/mol.
Step 2: Apply Graham's Law of Diffusion.
Graham's Law states that the ratio of the rates of diffusion of two gases is inversely proportional to the square root of the ratio of their molar masses:
Let gas 1 be ethane () and gas 2 be the unknown gas.
Given:
Rate mol/h
Rate mol/h
g/mol
Substitute the values into Graham's Law:
Step 3: Solve for the molar mass of the unknown gas ().
Square both sides of the equation:
Rounding to two significant figures (based on the given rates):
The molar mass of the unknown gas is .
Part a· 3 steps
Kr and O
Determine the molar masses of Kr and O.
Molar mass of Krypton (Kr) = 83.80 g/mol
Molar mass of Oxygen () =Identify which gas diffuses more rapidly.
The gas with the lower molar mass diffuses more rapidly. Since (32.00 g/mol) is less than (83.80 g/mol), oxygen () diffuses more rapidly.
Calculate the relative rates of diffusion.
Using Graham's Law:
Oxygen () diffuses more rapidly. The relative rate is .
Part b
N and acetylene (CH)
Determine the molar masses of N and CH.
Molar mass of Nitrogen () =
Molar mass of Acetylene () =Identify which gas diffuses more rapidly.
The gas with the lower molar mass diffuses more rapidly. Since (26.036 g/mol) is less than (28.02 g/mol), acetylene () diffuses more rapidly.
Calculate the relative rates of diffusion.
Using Graham's Law:
Acetylene () diffuses more rapidly. The relative rate is .
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