A 1.8 mole sample of a compound weighs 195 g and is found to be 11.18% H and 88.82% C. What is the molecular formula for the compound?

C8H12

Explanation:

First find the molar mass

195/1.8 × 1 = 108.3 gmol-1

Then the molecular formula

Mass of C in 1 mole of compound = 88.82×108.3/100

= 96.2 g

Mass of H in 1 mol of.the compound = 108.3×11.18/100 = 12.11 g

Divide the mass by their molar masses to get no. of moles in 108.3 g of compound or 1 mole of compound

Moles of C in one Mole of compound = 96.2g/12 gmol-1 = 8 mol

Moles of H in 1 mole of compound = 12.11g/1 gmol-1 =12 mol

Since we need the molecular formula it's C8H12

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).