The octane number of a fuel whose performance is the same as that of a mixture of 55 g of 2,2,4- trimethly pentane and 45 g of n-heptane is ?

Chrisbridge

4 years ago

The total mass of 2,2,4-trimethylpentane (iso-octane) and n-heptane = (55 + 45) = 100g

% of 2,2,4-trimethylpentane = 55/100 × 100 = 55%

% of n-heptane = 45/100 × 100 = 45%

Therefore octane number = 55% of 100 + 45% of 0 = 55%

Efranklyn

5 years ago

B is very correct because the octane number of any straight chain hydrocarbon in this case n- heptane is 0
The octane number of branch chain hydrocarbon is numerically 100 but the question emphasized on 55g
Therefore 0g + 55g = 55

Khobraxc

1 year ago

mass of 2,2,4- trimethylpentane × 100÷mass of mixture
= 55×100÷(55+45)
= 55