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dry hydrobromic acid, and how you would show that it is soluble in water and acid.

463. A cylinder standing over mercury is half filled with sulphuretted hydrogen ; a thin glass bulb containing bromine is passed up and then broken in the gas, What reaction occurs, and how does it affect the volume of gas in the cylinder?

464. How may the composition of hydrobromic acid be ascertained ?

465. Express by equations the reactions which occur when hydrobromic acid is added to (a) zinc, (6) silver nitrate, (c) chlorine, (d) manganese dioxide.

466. Aqueous solution of hydrobromic acid having a specific gravity of 1'515 has been found to contain 4908 per cent. of the gas. How much silver nitrate is needed to precipitate 100 c.c. of the solution ?

467. Do chlorine and bromine unite together? How could you distinguish between a solution of chlorine in bromine and a compound of the two elements ?

468. No compound of bromine with oxygen is at present known.

Suggest methods for attempting to prepare such a compound.

469. Give different methods for the preparation of

hypobromous acid. How would you distinguish it from hypochlorous acid ?

470. What occurs when bromine is left in contact with slaked lime, and what is the action of (a) hydrochloric acid, (6) nitric acid, on the product?

471. Express by equations the actions of (a) chlorine on bromine water, (6) bromine on caustic potash, (c) bromine water on silver bron ate.

472. What occurs when heat is applied to (a) bromic acid, (6) potassium bromate?

473. How is perbromic acid obtained ? Compare its properties with those of perchloric acid.

COMPOUNDS OF IODINE.

474. Do iodine and hydrogen combine together directly, and if so, how ?

475. State fully what occurs when strong sulphuric acid is dropped on potassium iodide.

476. How is hydriodic acid usually prepared ? How would you obtain (a) the dry gas, (6) a saturated aqueous solution of it ?

477. What occurs when a current of sulphuretted hydrogen is passed through a solution of iodine?

478. What are the properties of hydriodic acid, and what occurs when it is strongly heated ?

479. How niany cubic centimetres of hydriodic acid at N.T.P. are required to weigh the same as 1,000 of hydrogen ?

480. What is the action on hydriodic acid of (a) chlorine, (6) bromine, (c) iodine, (d) sulphur dioxide ?

a

481. What volume of hydriodic acid at N.T.P. contains i gramme of iodine, and how could it be extracted ?

482. Illustrate the action of hydriodic acid on organic compounds by explaining how it acts on tartaric acid and on glycerine.

483. Name six soluble and six insoluble iodides, and state what is the action of chlorine on each.

484. How could you detect each of the constituents in a mixture of potassium chloride, bromide, and iodide ?

485. Give a short account of the compounds of iodine with chlorine and with bromine.

486. Find the percentage composition and formulæ of the chlorides of iodine, from the following data :

(a) 0-521 gramme chloride contained 0.283 gramme

iodine and oʻ238 gramme chlorine. (6) 0*732 gramme chloride contained o 574 gramme

iodine and oʻ158 gramme chlorine. 487. What evidence is there for supposing the existence of hypoiodous acid ?

488. How is iodic acid obtained, and what occurs when it is heated ?

489. What is the action on iodine of (a) nitric acid, (6) caustic potash ?

490. What weight of iodic acid contains 1'567 gramme iodine, and by what reactions could it be obtained from it ?

491. How are periodic acid and the periodates respectively prepared ?

492. Write the formulæ of all the known compounds of the halogens with (a) hydrogen, (6) oxygen, (c) hydrogen and oxygen.

493. Chlorine is passed into water containing 23 grammes iodine in suspension. What volume at N.T.P. is required to convert all the iodine into iodic acid ?

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