STOICHIOMETRY QUESTIONS

STOICHIOMETRY QUESTIONS

STOICHIOMETRY

Required data:  Mass  Numbers: Ba = 137, Zn = 65.5, Fe = 56, O = 16

1.         The specific gravity of a solution is 1.8 g mL^–1. It has 62% w/w of acid. The mass of acid present in 500 ml solution is :

            (a)  550 g                                                      (b)  600 g

            (c)  558 g                                                      (d) 570 g

2.         A sample of crystalline Ba(OH)₂ . xH₂O weighing 1.578g was dissolved in water and the solution required 40 mL of 0.25N HNO₃ for complete reaction. The number of molecules of water of crystallization in base are :

            (a)  7                                                             (b)  8

            (c)  6                                                             (d) 5

3.         A solution of ethanol in water is 10% v/v. If the solution and pure ethanol have densities 0.9886 g/cc and 0.785 g/cc respectively, % w/w of ethanol is :

            (a)  7.94                                                        (b)  12.11

            (c)  11.22                                                      (d) 9.11

4.         K₄Fe(CN)₆ reacts with Zn²⁺ forming K₂Zn₃[Fe(CN)₆]₂. The volume of 0.036 M K₄Fe(CN)₆required to react with 150 mg of Zn²⁺ in solution is :

            (a)  40 ml                                                      (b)  45 ml

            (c)  42.4 ml                                                   (d) 48.52 ml

5.         The mineral haematite is Fe₂O₃. Haematite ore contains unwanted material called gangue in addition to Fe₂O₃. If 5.0 kg of ore contains 2.78 kg of Fe, the percentage purity of Fe₂O₃ is :

            (a)  85.54 %                                                  (b)  79.43%

            (c)  89.6 %                                                    (d) 100 %

SUBJECTIVE PROBLEMS

Required data:  Mass Numbers: Na = 23, K = 39, Cl = 35.5, S = 32, O = 16

1.         1 volume of a gaseous organic compound A and just sufficient amount of oxygen required for complete combustion, yielded on burning 4 volumes of CO₂, 6 volumes of water vapour and 2 volumes of N₂. All volume measured at same T and P and the compound contains only C, H, N. Calculate :

            (i)  How many volume of O₂ are required for complete combustion? 

            (ii) What is molecular formula of A?

2.         1g sample containing KCl and NaCl on treatment with H₂SO₄ gave 1.18 g of a mixture of K₂SO₄ and Na₂SO₄. Determine the percentage composition of the mixture.

ANSWERS OF OBJECTIVE QUESTIONS

1.         (c)  

2.         (b)            

3.         (a)     

4.         (c)     

5.         (b)