Answer:
C₇H₈
Solution:
Step 1: Convert mg into g as;
8.79 mg CO₂ = 0.00879 g CO₂
2.06 mg H₂O = 0.00206 h H₂O
Step 2: Moles of CO₂ and H₂O as;
Mole of CO₂ = mass of CO₂ ÷ M.mass of CO₂
Mole of CO₂ = 0.00879 g ÷ 44 g.mol⁻¹
Mole of CO₂ = 0.0002 mol
Also,
Mole of H₂O = mass of H₂O ÷ M.mass of H₂O
Mole of H₂O = 0.00206 g ÷ 18 g.mol⁻¹
Mole of H₂O = 0.0001144 mol
Step 3: Finding out moles of C and H as;
As 1 mole of CO₂ has 1 mole of C so, 0.0002 mol CO₂ will contain 0.0002 mol of C.
Aslo, 1 mole of H₂O has 2 moles of H so, 0.0001144 mol H₂O will contain (0.0001144 × 2) 0.0002288 moles of H.
So,
Moles of C = 0.0002 mol
Moles of H = 0.0002288 mol
Step 4: Find the simplest ratio;
Divide both moles with the smallest mole value as;
C = 0.0002 ÷ 0.0002 = 1
H = 0.0002288 ÷ 0.0002 = 1.14
Step 5: Get the whole number by multiplying the ratio by 7,
C = 1 ×7 = 7
H = 1.14 × 7 = 8
Result:
The Empirical formula (which is also the molecular formula) of TOLUENE is C₇H₈
