Explore topic-wise InterviewSolutions in Current Affairs.

ELECTRO plating:

It‟s a PROCESS in which the coating metal is deposited on the BASE metal by passing a direct current through an electrolytic solution CONTAINING the soluble salt of the coating metal.

Electro less plating:

It is a technique of depositing of a NOBLE metal from its salt solution on a catalytically active surface of a base metal by using a suitable reducing agent.

Electro plating:

It‟s a process in which the coating metal is deposited on the base metal by passing a direct current through an electrolytic solution containing the soluble salt of the coating metal.

Electro less plating:

It is a technique of depositing of a noble metal from its salt solution on a catalytically active surface of a base metal by using a suitable reducing agent.

Electroplating:

• It is carried out by passing current
• Separate anode is employed
• Anodic REACTION is M → Mn+ + ne-
• Thickness of the plating is 1-100μm

Electroless plating:

• Used REDUCING agent
• Catalytic surface of the SUBSTRATE ACTS as an anode
• Anodic reaction is R → 0 + ne-
• It has a thickness of 1-100μm

Electroplating:

Electroless plating:

PAINT is a mechanical dispersion of ONE or more FINELY divided pigments in a medium (thinner + vehicle) .When paint is applied to a metal surface, the thinner evaporates, while the vehicle undergoes slow OXIDATION forming a pigmented film.

Paint is a mechanical dispersion of one or more finely divided pigments in a medium (thinner + vehicle) .When paint is applied to a metal surface, the thinner evaporates, while the vehicle undergoes slow oxidation forming a pigmented film.

1. SACRIFICIAL ANODE method 
2. IMPRESSED current CATHODIC method

Because such a combination will not permit GALVANIC CORROSION to take PLACE.

Because such a combination will not permit galvanic corrosion to take place.

The RATIO of the VOLUME of the oxide FORMED to the volume of the metal CONSUMED is pilling BED worth rule

The ratio of the volume of the oxide formed to the volume of the metal consumed is pilling bed worth rule

Chemical corrosion:

1. It occurs dry state
2. Local attack to metal by environment
3. Chemical corrosion is self-controlled
4. It follows adsorption mechanism
5. Ex: formation of mild scale on IRON surface

Electrochemical corrosion:

1. Wet state (i.e) presence in MOISTURE
2. Large number of CATHODIC and anodic AREAS
3. It is continuous PROCESS
4. It follows electrochemical reaction
5. Ex: rusting of iron in moisture

Chemical corrosion:

Electrochemical corrosion:

It occurs due to the EXISTENCE of separate “ANODIC” and “cathodic” areas between which current flows through the conducting SOLUTION. At anodic area oxidation occurs and anodic part of metal is destroyed.

1. GALVANIC corrosion.
2. Concentration cell / Differential aeration corrosion.

It occurs due to the existence of separate “anodic” and “cathodic” areas between which current flows through the conducting solution. At anodic area oxidation occurs and anodic part of metal is destroyed.

It is known as dry corrosion. It is due to the local attack of metal SURFACES by the atmospheric gases like oxygen,H2S,SO2 , N2, etc.

3 types.

1. OXIDATION Corrosion.
2. Corrosion by other gases.
3. Liquid-metal corrosion.

It is known as dry corrosion. It is due to the local attack of metal surfaces by the atmospheric gases like oxygen,H2S,SO2 , N2, etc.

3 types.

1. Air and moisture.
2. Electrolytes in water.
3. Presence of impurities in metal.
4. Presence of GASES LIKE CO2 and SO2
5. Differential AERATION.

1. CHEMICAL CORROSION. 
2. ELECTROCHEMICAL corrosion

The GRADUAL DESTRUCTION of the metal or an alloy SURFACE by the chemical or electrochemical reaction with its environment. (i.e) metal into metal OXIDE.

The gradual destruction of the metal or an alloy surface by the chemical or electrochemical reaction with its environment. (i.e) metal into metal oxide.

E = Eo + 0.0591/n log [Mn+]

Application:

1. It is used to CALCULATE electrode potential of unknown metal.
2. CORROSION TENDENCY of metals can be predicted.
3. APPLICATIONS of emf series.

E = Eo + 0.0591/n log [Mn+]

Application:

To CALCULATE the STANDARD emf of the cell.,Relative ease of oxidation or reduction.
Displacement of one element by the other., Hydrogen displacement behavior. Determination of equilibrium constant (K) for the reaction.

To calculate the standard emf of the cell.,Relative ease of oxidation or reduction.
Displacement of one element by the other., Hydrogen displacement behavior. Determination of equilibrium constant (K) for the reaction.

When various TYPES of metallic ELECTRODES are ARRANGED in their increasing ORDER of standard REDUCTION potential on the basis of hydrogen scale is known as emf series.

When various types of metallic electrodes are arranged in their increasing order of standard reduction potential on the basis of hydrogen scale is known as emf series.

Determination of SPARINGLY soluble salt.,Determination of the VALENCY ion. Determination of STANDARD FREE energy change and K.
Potentiometric titrations can be carried out.,Hydrolysis constant can be DETERMINED.

Determination of sparingly soluble salt.,Determination of the valency ion. Determination of standard free energy change and K.
Potentiometric titrations can be carried out.,Hydrolysis constant can be determined.

It is MEASURED by EMF.: “The difference of potential which causes FLOW of electrons from one electrode of higher potential to the other electrode of lower electrode potential”.EMF= ER-EL

It is measured by EMF.: “The difference of potential which causes flow of electrons from one electrode of higher potential to the other electrode of lower electrode potential”.EMF= ER-EL

Oxidation POTENTIAL: The tendency of a metallic ELECTRODE to LOSE ELECTRONS.

REDUCTION potential: The tendency of a metallic electrode to gain electrons.

Oxidation potential: The tendency of a metallic electrode to lose electrons.

Reduction potential: The tendency of a metallic electrode to gain electrons.

When a METALLIC electrode is placed in its own salt solution, two types of reaction TAKES place.

•  +ve IONS MAY pass into the solution. M → Mn+ + ne- (OXIDATION)
• +ve ions from the solution may deposit over the metal. Mn+ + ne-→M (reduction)

The above reaction takes place in an electrode then it is known as an origin of electrode potential.

When a metallic electrode is placed in its own salt solution, two types of reaction takes place.

The above reaction takes place in an electrode then it is known as an origin of electrode potential.

It is the measure of tendency of a metallic electrode to LOSE or gain electrons, when it is in contact with its own salt SOLUTION. It is DENOTED as “E”

It is the measure of tendency of a metallic electrode to lose or gain electrons, when it is in contact with its own salt solution. It is denoted as “E”

Both REDUCTION and OXIDATION takes PLACE SIMULTANEOUSLY in a cell reaction then it is known as redox reaction of an electrochemical cell.

Both reduction and oxidation takes place simultaneously in a cell reaction then it is known as redox reaction of an electrochemical cell.

A cell which converts chemical ENERGY into ELECTRICAL energy is KNOWN as electrochemical cell. Example: Daniel cell , Batteries.

A cell which converts chemical energy into electrical energy is known as electrochemical cell. Example: Daniel cell , Batteries.