Vehicular exhaust is also responsible for atmospheric pollution and causes acid rain. At very high temperatures inside an internal combustion engine, nitrogen and oxygen react to form nitrogen dioxide

Question

Vehicular exhaust is also responsible for atmospheric pollution and causes acid rain. At very high temperatures inside an internal combustion engine, nitrogen and oxygen react to form nitrogen dioxide according to the following reactions:

$N_{2} + O_{2} \to 2 NO$

$2 NO + O_{2} \to 2 N O_{2}$

The pollutant NO₂ reacts with water present in rain to form nitric acid and nitrous acid.

$2 N O_{2} + H_{2} O \to H N O_{2} + H N O_{3}$

Atmospheric air contains 80% N₂ and 20% O₂ by volume. Pure liquid heptane ( $C_{7} H_{16}$ ) is used as the fuel. Exhaust analysis indicates that the first reaction proceeds about 10%, while the other two reactions proceed with 100% yield.

Calculate the minimum volume of air (in liters) (at STP) required for the complete combustion of 266.67 mL of heptane ( $d = 0.75 g m L^{- 1}$ ). Assume O₂ reacts with N₂ and heptane only.

TestHub · Accepted Answer

Let's assume V liters to be the volume of air. V N 2 ​ ​ N 2 ​ + O 2 ​ 5 4 V ​ V O 2 ​ ​ re mainin g C 7 ​ H 16 ​ + 11 O 2 ​ 100 266.67 ​ × 4 3 ​ ​ = 100 80 ​ V ; V O 2 ​ ​ = 5 V ​ → 2 NO 5 V ​ = 10 9 ​ ( 5 V ​ ) → 7 CO 2 ​ + 8 H 2 ​ O 10 9 ​ ( 5 V ​ ) ​

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