Question

octane has chemical formula of C₈H₁₈ and is the main component in gasoline .Assume a 1.5 litre 4 stroke 4 cylinder automobile engine running on octane .if the engine is running at 3000rpm and utilize all incoming air to combust octane while the car is moving at 120Km/h what is the fuel consumption of the car in km/l .1 l of air contain 0.25g of o_{2. .}Density of octane is 700g/l. Take relative atomic masses as c=12, o= 16 and H=1.

Answer 1

$2 C_8H_{18} + 25 O_2 --> 16 CO_2 + 18 H_2O$

Molar mass of $C_8H_{18}= 8(12)+18(1)=114$

Molar mass of $O_2=2(16)=32$

Moles of $O_2=\frac{0.25}{32}=0.0078moles$

Moles of octane $=\frac{2}{25}×0.0078=0.00063moles$

Mass of octane $=0.00063×114=0.0713g$