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21. Consider the following chemical reaction: N2+ O2 2 NO If 10.0 g of N2 reacts with excess oxygen then how many grams of NO can be formed? A) 10.7 g B) 21.4 g C) 32.9 g D) 42.8 g Page 4 of 8

User Juan Leni
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Answer: The correct answer is Option B.

Step-by-step explanation:

To calculate the number of moles, we use the equation:


\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}} ....(1)

  • For
    N_2:

Given mass of nitrogen gas = 10 g

Molar mass of nitrogen gas = 28 g/mol

Putting values in above equation, we get:


\text{Moles of iron oxide}=(10g)/(28g/mol)=0.357mol

The given chemical reaction follows:


N_2+O_2\rightarrow 2NO

As, oxygen gas is present in excess. Thus, it is considered as an excess reagent and nitrogen is considered as a limiting reagent because it limits the formation of products.

By Stoichiometry of the reaction:

1 mole of nitrogen gas produces 2 moles of nitrogen oxide.

So, 0.357 moles of nitrogen gas will produce =
(2)/(1)* 0.357=0.714mol of nitrogen oxide.

Now, calculating mass of nitrogen oxide by putting values in equation 1, we get:

Moles of nitrogen oxide = 0.714 mol

Molar mass of nitrogen oxide = 30 g/mol

Putting values in equation 1, we get:


0.714mol=\frac{\text{Mass of nitrogen oxide}}{30g/mol}\\\\\text{Mass of nitrogen oxide}=21.4g

Hence, the correct answer is Option B.

User Bert Verhees
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