Chemistry Class 11 NCERT Solutions: Chapter 1 Some Basic Concepts of Chemistry Part 8

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Q: 22. If the speed of light is calculate the distance covered by light in ns.

Answer:

According to the question:

Time taken to cover the distance

Speed of

Distance travelled by light in 2.00 ns

Q: 23. In a reaction

Identify the limiting reagent, if any, the following reaction mixtures.

(i)

(ii)

(iii)

(iv)

(v)

Answer:

A limiting reagent determines the extent of a reaction. It is the reactant which is the first to get consumed during a reaction, thereby causing the reaction to stop and limiting the amount of products formed.

(i) According to the reaction, 1 mol of A reacts with 1 mol of B. Thus, 200 molecules of B will react with 200 atoms of A, thereby leaving 100 atoms of A unreacted. Hence, B is the limiting reagent.

(ii) According to the reaction, 1 mol of A reacts with 1 mol of B. Thus, 2 mol of A will react with only 2 mol of B. As a result, 1 mol of A will not be consumed. Hence, A is the limiting reagent.

(iii) According to the given reaction, 1 atom of A combines with 1 molecule of B. Thus, all 100 atoms of A will combine with all 100 molecules of B. Hence, the mixture is stoichiometric where no limiting reagent is present.

(iv) 1 mol of atom A combines with mol of molecule B. Thus, 2.5 mol of B will combine with only 2.5 mol of A. As a result, 2.5 mol of A will be left as such. Hence, B is the limiting reagent.

(v) According to the reaction, 1 mol of atom a combines with 1 mol of molecule B. Thus, 2.5 mol of A will combine with only 2.5 mol of B and the remaining 2.5 mol of B will be left as such. Hence, A is the limiting reagent.

Q: 24 Dinitrogen and dihydrogen react with each other to produce ammonia according to the following chemical equation:

(i) Calculate the mass of ammonia produced if dinitrogen reacts with of dihydrogen.

(ii) Will any of the two reactants remain unreacted?

(iii) If yes, which one and what would be its mass?

Answer:

(i) Balancing the given chemical equation,

From the equation, of dinitrogen reacts with mole of dihydrogen to give mole of ammonia.

Of dinitrogen will react with of dihydrogen.

Given

Amount of dihydrogen

Hence, is the limiting reagent.

Hence, mass of ammonia produced by 2000

(ii) is the limiting reagent and is the excess reagent. Hence, will remain unreacted.

(iii) Mass of dihydrogen left unreacted