Answer
The molecular formula for the compound is C₂H₂
Step-by-step explanation
Given:
% composition: 92.3% carbon, 7.7% hydrogen.
Molecular mass = 26 amu
What to find:
The molecular formula for the compound.
Step-by-step solution:
Assume we have 100 grams total of the substance.
Grams C: 92.3/100 x 100 = 92.3 g
Grams H: 7.7/100 x 100 = 7.7 g
The next step is to convert the number of grams of each element into moles as shown below using the molar masses of H = 1.00784 g/mol and C = 12.011 g/mol.
Note: Mole = Mass/Molar mass.
Moles C = 92.3g/12.011 g/mol = 7.68 mol
Mole H = 7.7g/1.00784 g/mol = 7.64 mol
Now, let's divide the number of moles of each element by the smallest number obtained:
C = 7.68/7.64 = 1
H = 7.64/7.64 = 1
The empirical formula for this compound is CH
Using the molecular mass of 26 amu, the molecular formula is calculated as follows:
(Empirical mass)n = (Molecular mass)
(CH)n = 26
(12.011 + 1.00784)n = 26
(13.01884)n = 26
Divide both sides by 13.01884
n = 26/13.01884
n = 2
Moleculare formula = (CH)₂ = C₂H₂
Therefore, the molecular formula for the compound is C₂H₂