Question

The equation for the burning of octane is:

\[\ce{2C8H18 + 25O2 -> 16CO2 + 18H2O}\]

1. How many moles of carbon dioxide are produced when one mole of octane burns?
2. What volume, at STP, is occupied by the number of moles determined in (a)?
3. If the relative molecular mass of carbon dioxide is 44, what is the mass of carbon dioxide produced by burning moles of octane?
4. What is the empirical formula of octane?

Answer 1

a. 2 moles of C₈H₁₈ produces = 16 moles of CO₂

∴ 1 mole of C₈H₁₈  will produce = `16/2`

= 8 moles of CO₂

b. 1 mole of CO₂ occupies = 22.4 L at STP.

∴ 8 moles of CO₂ will occupy = 22.4 × 8

= 179.2 L at STP

c. 1 mole of carbon dioxide has molecular mass = 44

16 moles of carbon dioxide has molecular mass = 44 × 16

= 704 g

d. Empirical formula of octane is C₄H₉.