CBSE (Science) Class 11CBSE
Share

# In Ostwald’S Process for the Manufacture of Nitric Acid, the First Step Involves the Oxidation of Ammonia Gas by Oxygen Gas to Give Nitric Oxide Gas and Steam. What is the Maximum Weight of Nitric Oxide that Can Be Obtained Starting Only with 10.00 G. of Ammonia and 20.00 G of Oxygen? - CBSE (Science) Class 11 - Chemistry

ConceptOxidation Number Balancing of Redox Reactions

#### Question

In Ostwald’s process for the manufacture of nitric acid, the first step involves the oxidation of ammonia gas by oxygen gas to give nitric oxide gas and steam. What is the maximum weight of nitric oxide that can be obtained starting only with 10.00 g. of ammonia and 20.00 g of oxygen?

#### Solution 1

The balanced chemical equation for the given reaction is given as:

4NH_(3(g)) +   5O_(2(g)) ->     4NO_(g) +    6H_2O_(g)

4xx 17g             5xx 32g                 4xx 30g                    6xx18g

= 68g  =160g  =120g  = 108g

Thus, 68 g of NH3 reacts with 160 g of O2.

Therefore, 10g of NH3 reacts with (160xx10)/68 g of O_2 or  23.53 g of O_2

But the available amount of O2 is 20 g.

Therefore, O2 is the limiting reagent (we have considered the amount of O2 to calculate the weight of nitric oxide obtained in the reaction).

Now, 160 g of O2 gives 120g of NO.

Therefore, 20 g of O2 gives (120xx20)/160 g of N, 15 g of NO

Hence, a maximum of 15 g of nitric oxide can be obtained

#### Solution 2

The balanced equation for the reaction is:

4NH_3(g) + 5O_2(g) ->  4NO(g) +  6H_2O(g)

4xx17                    5xx3                        4xx30

= 68 g    = 160 g       = 120 g

Here 68 g of NH_3 will O_2 = 160g

:. 10 g of NH_3 will react will O_2 = (160g)/(68g) xx 10g = 23.6  g

But the amount of O2 which is actually available is 20.0 g which is less than the amount which is needed. Therefore, 02 is the limiting reagent and hence calculations must be based upon the amount of 02 taken and not on the amount of NH3 taken. From the equation,
160 g of 02 produce NO = 120 g

∴ 20 g of 02 will produce NO =120/160 x 20 = 15 g

Is there an error in this question or solution?

#### APPEARS IN

Solution In Ostwald’S Process for the Manufacture of Nitric Acid, the First Step Involves the Oxidation of Ammonia Gas by Oxygen Gas to Give Nitric Oxide Gas and Steam. What is the Maximum Weight of Nitric Oxide that Can Be Obtained Starting Only with 10.00 G. of Ammonia and 20.00 G of Oxygen? Concept: Oxidation Number - Balancing of Redox Reactions.
S