Question

The reaction between nitric oxide $(NO)$ and oxygen to form nitrogen dioxide $(N{O_2})$ is a key step in photochemical smog formation:
$2NO(g) + {O_2}(g) \to 2N{O_2}(g)$
The grams of $N{O_2}$ formed by the reaction of $1.20g$ of $NO$ is:
A: $7.2g$
B: $2.3g$
C: $1.8g$
D: $4.1g$

Answer 1

Hint: In the given reaction two moles of $NO$ react with one mole of ${O_2}$ to form two moles of $N{O_2}$. The molecular mass of nitric oxide is $30g$and the molecular mass of nitrogen oxide is $46g$ .
To find the number of moles of a given compound divide the given mass by it’s molecular mass.

Complete step by step answer:
The reaction that is given in the question is $2NO(g) + {O_2}(g) \to 2N{O_2}(g)$ . By analysing it is clear to us that one mole of nitric oxide produces one mole of nitrogen dioxide . The given mass of $NO$ is $1.20g$ . The molecular mass of $NO$ is $14 + 16 = 30g$ and the molecular mass of $N{O_2}$ is $14 + (16 \times 2) = 46g$ . So the number of moles of $NO$ will be $\dfrac{{1.2}}{{30}} = 0.04$ .From this we can say that the number of moles of $N{O_2}$ will be $0.04$ too. So the mass of nitrogen oxide formed will be $0.04 \times 46 = 1.8g$ . From the above explanation and calculation it is clear to us that

The correct answer of the above question is option C.

Additional information: Photochemical smogs is a type of smog which is formed in hot, dry and more populated cities. Photochemical smogs are formed when UV rays from the sun reacts with nitrogen oxides. Photochemical smogs are also known as Los Angeles smog. It is oxidising in nature. It is very harmful for animals, human beings and plants .

Note: always use the concepts of moles to solve this type of problem. First try to find for every mole of the reactant how much product is formed and after that try to relate according to the given question. To get the total mass of the compound formed, multiply the number of moles formed with the molecular mass of the compound.