basketane is a hydrocarbon that is 90.8% carbon. If the molar mass is between 130-140 g/mol find the molecular formula of the compound.

C₁₀H₁₂

Explanation:

90.8% of basketane (Hydrocarbon, contains only C and H) is Carbon, and 100-90.8 = 9.2% of the mass is hydrogen.

The molar mass is between 130-140g/mol, That means the moles of Carbon (Using its molar mass, 12.01g/mol) that are in basketane are between:

140g/mol /12.01g/mol *90.8%= 10.58 moles of C.

130g/mol / 12.01g/mol *90.8%= 9.83 moles of C.

As the moles of carbon must be given in a whole number, There are 10 moles of Carbon.

10 moles C * (12.01g / mol) = 120.1g/mol that are 90.8% of the molar mass. Molar mass of basketane is:

100% * (120.1g/mol / 90.8%) =

132.3g/mol.

The part of the molar mass due hydrogen must be:

132.3 g/mol - 120.1g/mol = 12.2 g/mol

As molar mass of hydrogen is 1g/mol, the moles of hydrogen are 12

And molecular formula is: