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595. What occurs when ammonia solution is added to nitric acid ? What occurs when the product is heated ? Give equation for both reactions.

596. Represent by equations the reactions caused by heating (a) ammonium nitrite, (6) ammonium nitrate.

597. How is nitrous oxide prepared and collected, and what are its properties ?

598. A glowing taper was rekindled when placed in a jar which contained either nitrous oxide or oxygen. How could you ascertain with certainty which gas was present?

599. If 100 litres of nitrous oxide at N.T.P. be decomposed into free oxygen and nitrogen, what increase in bulk will occur ?

600. How much phosphorus could be burned in 100 litres of nitrous oxide at N.T.P.?

601. Twenty grammes of nitrous oxide were obtained by heating ammonium nitrate, how much of the salt was used ?

602. Point out the resemblances between nitrous oxide and oxygen, and state how they may be distinguished (a) by chemical tests, () by physical tests.

603. Write an account of the preparation and properties of nitric oxide.

604. What is the weight of 5 litres of nitric oxide at N.T.P.? What volume at N.T.P. will 5 gramines of the gas occupy?

605. How can it be proved that nitrous oxide contains its own volume of nitrogen, and nitric oxide half its volume of nitrogen ?

606. If a gas-holder contains when full 25 grammes of oxygen, what weights of nitrous and of nitric oxides will it hold ?

607. What volume of nitrogen will be left in each case, by heating potassium in contact with 17 grammes of nitrous and nitric oxides?

608. What occurs when nitric oxide is passed over red-hot copper, and how much will the copper gain in weight when II litres of the gas at N.T.P. are passed over it?

609. Air is passed into i litre of nitric oxide standing over water, so long as brown fumes are forined. What gas remains after the have dissolved, and what is its volume ?

610. Answer the previous question for oxygen instead of air.

611. Under what circumstances does nitric oxide (a) extinguish burning phosphorus, (b) support its combustion ?

612. What happens when nitric oxide is passed into solution of ferrous sulphate?

613. What impurities are present in nitric oxide prepared by the action of nitric acid on copper? How is the gas obtained quite pure ?

614. Give different methods for obtaining nitrogen trioxide, and state what occurs when it is added to water.

615. What substance is produced when potassium nitrate is heated, and what is the action of dilute acids on the product ?

616. What volume of oxygen must be added to 1234 C.C. of nitric oxide, so as to convert it into nitrogen trioxide ?

617. What is the probable composition of a mixture produced by adding 3 volumes of dry nitric oxide to I volume of dry oxygen ?

618. How may nitrites be detected in presence of nitrates?

619. What occurs when dry lead nitrate is heated ? Give an equation for the reaction, and describe the oxide of nitrogen thus obtained.

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620. Why are nitrogen dioxide and tetroxide represented by the formulæ NO and NO, respectively, and not by N,0, and N,O,?

621. What is the action on nitrogen tetroxide of small and large quantities of water ?

622. How is nitrogen pentoxide obtained, and how is it related to nitric acid ?

623. What is the action of phosphorus pentoxide on nitric acid, and how may nitric acid be obtained from the product?

624. What naturally occurring compounds may be used for the preparation of nitric acid ? How do they generally occur, and how is their formation accounted for?

625. How is, nitric acid usually prepared (a) on the small scale, (b) on the large scale? What impurities are generally present in the commercial acid ?

626. How may nitric acid be obtained starting with hydrogen, oxygen, and nitrogen ?

627. How much sulphuric acid is needed to react on 129 tons of nitre so as to obtain nitric acid, and how much of the latter should be got from this weight of the salt ?

628. What are the best tests for nitric acid, and how may these tests be applied to the detection of nitrates ?

629. Starting with nitric acid, how may each of the oxides and acids of nitrogen be obtained ? Give equations.

630. Name all the bodies which can be obtained by the action of nitric acid of different strengths on zinc. Explain the formation of each and give equations.

631. What is the action of strong nitric acid on (a) sulphur, (6) mercury, (c) sulphur dioxide, (e) tin, (f) phosphorus ?

632. How much pure nitric acid is present in 159 tons of nitric acid, 100 grammes of which neutralize 44'3 grammes pure caustic potash ?

633. Name four metals which are not acted on by nitric acid, and state how solutions of each may be obtained.

634. What is aqui regia ? What substances are required to prepare it, and what gases does it contain ?

635. What is the formula of hyponitrous acid, and how is it related to nitrous and nitric acids ? How are its salts obtained ?

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