Lesson 7 Theme: «Indium»Grammar: The future simple tense. Listening: Unbreak my heart

2.Read the text. Use a dictionary, if necessary.

Text. Indium

Indium was regarded as a laboratory curiosity for many years and no commercial applications were attempted until 1924. It would hardly be possible to think of its application, for the available supply at that time was only one gram, with no immediate prospects of more.Indium seldom occurs in a mineral in quantities over 0.1 per ccnt.

Several methods of extracting indium from its ores should have been considered. According to one of them, indium-bearing zinc metal was treated with a quantity of dilute H₂SO₄which would dissolve almost all the material, leaving a residue of zinc. On this residue there was collected a spongy mass composed of lead, copper, cadmium, tin, arsenic, iron, and indium. Nitric acid was used to dissolve the spongy mass, after which the solution was evaporated with sulphuric acid. Lead sulphate was left behind on the filter.

The filtrate was treated with NH₃(aq) to precipitate In(OH)₃ and Fe(OH)₃ which were dissolved in HCl. The resulting solution was approximately neutralized and boiled with NaHSO₃, which precipitated the basic sulphite, In₂(SO₃)₃ ·In(OH)_3· 5H₂O. The basic sulphite was dissolved in sulphuric acid and pure In(OH)} was obtained by the addition of NH₃(aq).Indium exhibits properties characteristic of the aluminium group.

Indium burns in air with a blue flame to form the scsquioxidc, In₂O₃. If it were heated in the presence of galogens or sulphur, direct combination would take place. In each case indium goes to its highest oxidation state.

The other halides (InX and InX₂, where X is a galogen) have been prepared, with the possible exceptions of InF and InF₂. Only the halides, InX₃, are stable in the presence of water. There are three tri-fluorides of indium, the hydrates of the compositions InF₃·3H₂O and InF₃·9H₂O and the anhydrous salt, InF₃. Most indium compounds are soluble in water.

Indiy

Indiy ko'p yillar davomida laboratoriya qiziqishi sifatida qaraldi va 1924 yilgacha sanoat dasturiga kiritish amalga oshirilmagan. Uni qo'llash haqida o'ylashning iloji yo'q edi, chunki o'sha paytda mavjud bo'lgan ta'minot faqat 1 grammni tashkil etadi, ammo bundan keyingi istiqbollari yo'q edi. kamdan-kam minerallarda imdiy uchun 0,1 dan yuqori miqdorda bo'ladi.

Indiyni uning rudalaridan ajratib olishning bir necha usullari ko'rib chiqilishi kerak edi. Ulardan biriga ko'ra, indiy o'z ichiga olgan rux metallini suyultirilgan H₂SO₄ miqdori bilan ishlangan, bu deyarli barcha materiallarni eritib yuboradi va rux qoldig'ini qoldiradi. Ushbu qoldiqda qo'rg'oshin, mis, kadmiy, qalay, mishyak, temir va indiydan iborat. So`ng qoldiqni eritish uchun nitrat kislota ishlatilgan, undan keyin eritma sulfat kislota bilan bug'langandi. Qo'rg'oshin sulfat filtrda qoldi.

Filtrat HCl da eritilgan In (OH)₃ va Fe (OH)₃ cho'kmasi uchun NH₃ (aq) bilan ishlangan. Olingan eritma taxminan neytrallandi va NaHSO₃ bilan qaynatildi, u asosiy sulfitni In₂ (SO3) 3 · In (OH) ₃ · 5H₂O cho'ktirdi. Asosiy sulfit oltingugurt kislotasida eritilib, NH3 qo'shilishi bilan sof In (OH)} olinadi .Indiy alyuminiy guruhiga xos xususiyatlarni namoyish etadi.