3 Part One. The Predicate

Section II
Mashq 2. Quyidagi so'zlarning ma'nosini toping

classification, principle, practical, equilibrium, discussion, nomenclature, neutralize, action, demonstrate, result, activity, electrical, dissociation, variation, scheme

Mashq 3. Quyidagi so’zlarni matndan toping

perhaps, involve, vast, devote, sour, taste, reverse, essential, strength, consequence, apply, be responsible for, advance

Text 25 В

Matnni o’qing (o’qish vaqti — 3 daqiqa).

The Arrhenius Theory of Acids and Bases
There is perhaps no other class of equilibria as important as that involving acids and bases. As We continue the study of chemistry, We shall find that the classification “acid-base reaction'* includes a vast numberof chemical changes, so that the principles and practical points are ofvery general use. Now We must devote some time to a discussion of nomenclature and classification of acids and bases.

The classification of substances as acids was at first suggested by their sour taste, and alkalis were taken as those substances that could reverse or neutralize the action of acids. It was thought also Uiat an acid must have, as necessary constituent, the clement oxygen, but in 1810 Davy demon­strated that hydrochloric acid contained only hydrogen and chlorine. Shortly thereafter the view was taken that all acids had hydrogen as an essential constituent.

An explanation of why acids had differing strengths was one of the important results of the Arrhenius ionic dissociation theory, developed between 1880 and 1890. The chemical activity and electrical conductivity of solutions o f acids were taken to be conscqucnccs of their reversible dissociation into ions, one of which was H’:

HCl = H⁺ + Cl^-.

The fact that different acids had different strengths was explained as a result of a variation o f the degree of dissociation. A similar scheme applied to the behaviour of bases, which were all thought to producc the hydroxyl ion in solution:

NaOH(s) = Na⁺(aq) + OH^-(aq).

Thus, the proton was responsible for acidic properties, and the hydroxyl ion was responsible for basic properties.

While this point of view was a considerable advance in chemical theory, it led to certain difficulties. The first of these concerned the nature of the proton in aqueous solution, and the second had to do with the fact that substances which did not contain hydroxyl ion were capable of acting as bases.

Mashq 3. Bir necha jumlada matnning asosiy tarkibini o'tkazib yuboring.

Mashq 4. Matndagi qaysi so'z "asosiy, asosiy" degan ma'noni anglatadi?

Mashq 5. Matnda quyidagi savollarga javob toping:

1. Nima uchun moddalarni kislotalar va asoslarga ajratish qiyin bo'lgan? 2. Kislotalarning xarakterli belgisi birinchi navbatda nima deb hisoblangan? 3. Devi kashf etishidan oldin qaysi element kislotalarning zarur tarkibiy qismi hisoblanadi? 4. Arrenius nazariyasi tomonidan tugunlarning xususiyatlariga qanday muhim holat tushuntirilgan? 5. Kislotalar va asoslarning harakatlarini belgilovchi omil nimadan iborat?

Mashq 6. Quyidagi jumlalarni to'ldiring:

1. The subject of this text is ... 2. In 1810 it was showed... 3. Hydrogenwas considered to be ... 4. Different strengths of different acids were due to ... 5. Bases were thought to produce ...