Corrosion

STATEMENT 1 Corrosion of iron is essentially an electrochemical phenomenon STATEMENT 2 : Corrosion reaction at anode : 2Fe(s)rarr2Fe^(3+)+6e^(-) STATEMENT 3: Corrosion reaction at cathode : O_(2)(g)+4H^(+)(aq)+4e^(-)rarr2H_(2)O(l)

(a) Corrosion is essentially an electrochemical phenomenon. Explain the reactions occurring during corrosion of iron kept in an open atmosphere. (b) Calculate the equilibrium constant for the equilibrium reaction Fe_((s)) + Cd_((aq))^(2+) hArr Fe_((aq))^(2+) + Cd_((s)) (Given : E_(Cd^(2+)|Cd)^(@) = -0.40 V , E_(Fe^(2+)|Fe)^(@) = -0.44V ).

The given figure shows the corrosion of iron in atmosphere. Fill in the blanks by choosing an appropriate option. At a particular spot of an object made of iron, ___(i)___ of iron to ferrous ion takes place and that spot behaves as ___(ii)___. Electrons released at anodic spot move through the metal and go to another spot on the metal and reduce oxygen in presence of H^+ . This spot behaves as ___(iii)___. The ferrous ions are further oxidised by atmospheric oxygen to ferric ions which come out as rust, __(iv)____ and with further production of ____(v)__ ions.

Match the properties and uses of alloys in List 1 with the appropriate answer from List 2. List 1. The alloy contains Cu and Zn, is List hard and is used in decorative articles 2. It is stronger than Aluminium, light and is used in making light tools. 3. It is lustrous, hard corrosion resistant and used in surgical instruments. 4. Tin lowers the melting point of the alloy and is used for soldering purpose 5. The alloy is hard, brittle takes up polish and is used for making statues. List 2 : A. Duralumin B Brass C. Bronze D. Stainless Steel E. Solder

Assertion (A) : Fe is protected from corrosing by connecting Mg metal with it. Reason (R) : Fe acts as cathode and Mg as anode which gradully disappears.

The formula of corrosive sublimate is

Which of the following is a highly corrosive salt?

Oxidation state of mercury in amalgam , calomel and corrosive sublimate is

Which statements about corrosive sublimate (HgCl_(2)) are correct?

H_(2)SO_(4) has very high corrosive action on skin because