Sulphur Chemistry Test

 

1 (a)  Give the atomic number of sulphur and the electronic configuration of its isolated atom.

                                                                                                [1]

 

(b)   For sulphur dioxide (SO2) and hydrogen sulphide (H2S) molecules and sulphate ions (SO42-) respectively, state the oxidation number of the sulphur.

                                                                                                [3]

 

(c)         Describe briefly, giving reagents, reaction conditions, and equations, how substances containing sulphur of oxidation number

(i)     +4,

(ii)  +6, and

(iii)        0,

respectively, could be obtained from sulphur dioxide.

                                                                                                [9]

 

(d)        In the reaction:

Na2H10S2O8 + 4Br2            2H2SO4 + 2NaBr + 6HBr

only the oxidation numbers of the sulphur and bromine alter. 

Calculate from the equation the oxidation number of the sulphur in Na2H10S2O8.

                                                                                                [2]

 

 

2 (a)  Briefly explain what is meant by the term allotropy in

relation to sulphur.                                             

                                                                                                [4]

 

Draw a diagram to illustrate the molecular structure of a solid allotrope of sulphur

                                                                                                [2]

 

(b)  When radioactive sulphur (35S)  slowly dissolves in hot aqueous sodium sulphite to give a solution of compound A, and the resulting solution is acidified, a precipitate B is formed which is the only radioactive product, no radioactivity remaining in solution. 

Explain these observations and indicate what information may be deduced regarding the structure of A.

                                                                                                [6]

 

3. (a)  Give the formula of each of the following compounds, and

identify the oxidation number of the sulphur in that compound.

 

(i)  sulphuric acid,

 

(ii)  sulphurous acid,

 

(iii)  barium sulphide,

 

(iv)  sodium thiosulphate,

 

(v)  sulphur hexafluoride.

                                                                                      [10]

 

(b) With reference to the manufacture of sulphuric acid from sulphur dioxide by the Contact Process, state

 

(i)  the equation for the oxidation reaction involved in the process,

 

(ii)  whether this reaction is exothermic or endothermic,

 

(iii)  the effect of temperature on the yield of reaction product,

 

(iv)  the effect of temperature on the rate of reaction,

 

(v)  the experimental conditions used in the actual process as carried out industrially.                               

                                                                                      [8]

 

(c)  Give two major applications of sulphuric acid in industry, stating clearly the function of the acid in each application.               

                                                                                      [4]

 

(d)  Describe a simple test for sulphate ions in solution.  Write an equation.

                                                                                       [3]

 

 

 

                                                                               (Total 52 marks)