What are the empirical and molecular formulas of a hydrocarbon if combustion of 2.10 g of the compound yields 6.59 g co2 and 2.70 g h2o and its molar mass is about 84 g/mol?

The empirical formula of hydrocarbon is CH2

The molecular formula of the hydrocarbon is C6H12

Explanation

Hydrocarbon is made up of carbon and hydrogen

Empirical formula calculation

Step 1: find the moles CO2 and H2O

moles = mass/molar mass

moles of CO2 = 6.59 g / 44 g/mol = 0.15 moles

moles of H2O = 2.70 g / 18 g/mol = 0.15 moles

Step 2: Find the moles ratio of Co2:H2O by diving each mole by smallest mole (0.15)

that is for CO2 = 0.15/0.15 = 1

For H2O = 0.15/0.15 = 1

therefore the mole ratio of Co2 : H2O = 1:1 which implies that 1 mole of Co2 and 1 mole of H2O is formed during combustion reaction.

From the the law of mass conservation the number of atoms in reactant side must be equal to number of atoms in product side

therefore since there 1 atom of C in product side there must be 1 atom of C in reactant side.

In addition there is 2 H atom in product side which should be the same in reactant side.

From information above the empirical formula is therefore = CH2

Molecular formula calculation

[CH2}n = 84 g/mol

[12 + (1x2) ] n = 84 g/mol

14 n = 84 g/mol

n = 6

multiply the each subscript in CH2 by 6

Therefore the molecular formula = C6H12