Tag: chemistry

When soap or detergent is added to water, this results in the formation of oil in water type emulsion.
The polar water-soluble ( hydrophilic) head is on the surface of the micelle whereas non-polar oil soluble (hydrophobic) tail is in the centre of the micelle. In the centre of the micelle, small oil droplets are present in which hydrophobic part of micelle dissolves.

The development step uses reducing chemicals, and the exposed silver-halide grains develop to pure silver. The oxidized developer is produced in this reaction, and the oxidized developer reacts with chemicals called couplers in each of the image-forming layers. This reaction causes the coupler to form a color, and this color varies depending on how the silver-halide grains were spectrally sensitized. A different color-forming coupler is used in the red, green, and blue sensitive layers. The latent image in the different layers forms a different colored dye when the film is developed.

Electroplating is the process of plating one metal onto another by hydrolysis, most commonly for decorative purposes or to prevent corrosion of a metal. Metal cladding is the bonding together of dissimilar metals. It is different from fusion welding or glueing as a method to fasten the metals together. In metal spraying a wide range of metals is sprayed onto the surface of another metal. All of these methods are used to prevent corrosion.

Rusting of iron is a redox reaction because iron is oxidised from $0$ to $+3$ oxidation state and oxygen is reduced from $0$ to $-2.$

Rust general formula is $Fe _2O _3.nH _2O$. It is basic in nature.

Coating of iron with zinc to prevent corrosion is called galvanization.
Steel is dipped in a bath of molten zinc. The zinc coated iron is called galvanized iron. Zinc $(E^o=-0.763 : V)$ is stringer reducing agent than iron $(E^o=-0.44 : V)$ and is more easily oxidized than iron . Thus during corrosion, Zn is oxidized instead of Fe.

During the charging of a lead accumulator cell, the electical energy is stored in the form of chemical energy. Thus, the electrical energy derives non-spontaneous chemical reactions. Hence, during charging, the lead accumulator cell acts as an electrolytic cell.

During charging of lead storage battery, sulphuric acid is regenerated. The net cell reaction during charging is $ PbS{ O } _{ 4 } +{ 2{ H } _{ 2 }O  }  \xrightarrow {  }  Pb  +  Pb{ O } _{ 2 }  +  2{ H } _{ 2 }{ SO } _{ 4 }  $

The following are true regarding rancidity. On keeping for long time, the oxidation of oils and fats, changes the taste and odor of food and makes them unfit for consumption. To prevent rancidity, food is stored in air tight containers. Rancidity can also be prevented by addition of antioxidants. To prevent rancidity, packed food items are flushed with an inert gas like nitrogen.

For lead accumulator battery, the oxidation reaction at anode  requires two moles of electrons. Similarly, the reduction reaction at cathode  requires two moles of electrons. Hence, the number of Faradays involved in the net reaction of Lead accumulator is 2.
Note: 1 Faraday is equal to the amount of charge on 1 mole of electrons.