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occurs when it is heated and when it is added to

water?

729. Give the names and formulæ of all oxyacids of sulphur.

730. What acid body is obtained by the action of zinc on sulphurous acid? What name was given to it at first, and what is its more systematic name?

731. By what reactions would you distinguish sulphurous acid from Schützenberger's acid?

732. How would you prepare a solution of sulphurous acid in water? Why can the acid not be obtained except in solution?

733. What occurs when an aqueous solution of sulphurous acid is (a) exposed to air, (b) added to infusion of rose leaves, (c) mixed with chlorine water?

734. How does sulphurous acid act as a bleaching agent? Compare its bleaching action with that of chlorine. Give equations.

735. What is the action of solution of iodine on sulphurous acid in dilute and in strong solutions? Express the reactions by equations.

736. If 432 c.c. of iodine solution (containing o'co5 gramme iodine in each c.c.) were added to a solution

of sulphurous acid (containing a little starch) before a blue colour appeared, how much sulphur dioxide was in solution?

737. Express by equations the reactions which occur when hydrochloric acid is added to (a) sodium sulphite, (b) sodium thiosulphate.

738. What is the action of sulphur dioxide on iodic acid, and how may the reaction be used as a test for the gas?

739. What is meant by an "antichlor"? the use of sulphur dioxide as an antichlor.

Explain

740. What occurs when sodium sulphite is digested with sulphur? Give the formula of the body produced, and show how it is related to sulphite and sulphate of sodium.

741. What reaction occurs when sodium sulphite is treated with zinc and a dilute acid?

742. How is sodium thiosulphate made on the large scale, and what is it used for in photography?

743. Give all the reactions by which you could distinguish a sulphite from a thiosulphate.

744. What occurs when a solution of iodine is added to a solution of sodium thiosulphate? Name all the

sulphur acids which decolorize iodine solution. Give the reactions in each case.

745. How was sulphuric acid originally prepared? What is Nordhausen sulphuric acid, and how is it prepared?

746. How much sulphuric anhydride when dissolved in water will yield 1298 grammes of sulphuric acid?

747. In this country 850,000 tons of sulphuric acid are made annually. What weight of sulphur is contained in this quantity?

748. Name the materials necessary for the manufacture of sulphuric acid, and state how each is used.

749. How may the process for preparing sulphuric acid be illustrated on the small scale? Sketch the apparatus. 750. Explain fully the theory of the formation of sulphuric acid in the leaden chambers. Give equations to represent the reactions supposed to occur.

751. What is the composition of the crystalline compound often found in the leaden chambers? What is the action of water on it?

752. How is sulphuric acid made on the large scale? Sketch the plant required.

753. Represent by equations the reactions which occur when iron pyrites is heated (a) in a limited quantity of air, (b) with excess of air.

754. What occurs when nitrous fumes are left in contact with sulphuric acid, and what occurs

addition of water to such acid?

on the

“Gay

755. What is the use in the manufacture of sulphuric acid of the towers called (a) Glover's, (b) Lussac's?"

756. Describe different methods for concentrating the dilute acid obtained in the leaden chambers, and state how " rectified vitriol" is obtained.

757. How much sulphuric acid should theoretically be obtained from 100 tons of sulphur, and how much from 100 tons of iron pyrites containing 492 per cent. of sulphur?

758. What impurities are usually contained in conmercial sulphuric acid? How do you account for the presence of each, and how may they be completely removed?

759. If 1363 tons of sulphuric acid were practically obtained from 100 tons iron pyrites, find the percentage of sulphur in that ore.

760. How much sulphuric acid should be theoretically obtained from 197 tons of iron pyrites, if the burnt ore contained 2'74 per cent. of sulphur?

761. What Occurs when sulphuric acid vapour is

heated?

762. What occurs when sulphuric acid is left exposed to the air?

763. What is the action of sulphuric acid on lead? What is the composition of the precipitate which forms when commercial sulphuric acid is diluted with water?

764. How would you detect the presence of arsenic in sulphuric acid, and how do you account for its presence?

765. How much sulphuric acid is contained in a litre of a liquid, of which Ico c.c. require 1'97 gramme barium chloride for complete precipitation?

766. How much sulphuric acid is required exactly to decompose 2 345 grammes of sodium carbonate?

767. How would you prepare a solution of sulphuric acid, such that each cubic centimetre should contain 0098 gramme H2SO4?

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