Question

7. A compound has the empirical formula CH and a molar mass of 78.11 g/mol. What is its molecular formula?

8. Upon combustion, a compound containing only carbon and hydrogen produces 1.83 g CO₂ and 0.901 g H₂O. Find the empirical formula of the compound.

9. Write a balanced equation for the reaction between solid cobalt(III) oxide and solid carbon to produce solid cobalt and carbon dioxide gas.

Answer 1

7)

molar mass = 78.11 g/mol

emperical formula = CH

emperical formula mass = 12 + 1 = 13 g/mol

n = molar mass / emperical formula mass

= 78.11 / 13

= 5.85

= 6

molecular formula = C6H6

8)

moles of CO2 = 1.83 / 44 = 0.0416

moles of C =0.0416

moles of H2O = 0.901 / 18 = 0.05

moles of H = 0.100

   C             H

0.0416     0.100

1               2.5

emperical formula = C2H5