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

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

Answer:

According to the question:

Time taken to cover the distance Equation

Equation

Speed of Equation

Distance travelled by light in 2.00 ns

Equation

Equation

Equation

Equation

Q: 23. In a reaction

Equation

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

(i) Equation

(ii) Equation

(iii) Equation

(iv) Equation

(v) Equation

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 Equation 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:

Equation

(i) Calculate the mass of ammonia produced if Equation dinitrogen reacts with Equation 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,

Equation

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

Equation

Equation Of dinitrogen will react with Equation of dihydrogen.

Given

Amount of dihydrogen Equation

Hence, Equation is the limiting reagent.

Equation

Hence, mass of ammonia produced by 2000 Equation

Equation

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

(iii) Mass of dihydrogen left unreacted Equation

Equation

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