1. Define: Unit Operation. Useful Physical Changes Occur in the Chemical Industry Is Known As a Unit Operation

INTREVIEW QUESTIONS

1. Define: Unit operation. Useful Physical changes occur in the chemical industry is known as a Unit Operation. Example: Distillation, Filtration, Drying, Extraction, Gas absorption, Crystallization, etc.

2. Define: Unit process. Useful Chemical changes with or without physical change occur in chemical industry are known as a Unit Process. Example: - Oxidation, Reduction, Alkylation, Sulfonation, Chlorination, etc. . 3. Define: Boiling Point and Bubble Point. Boiling Point: -It is a temperature of a liquid at which the vapour pressure of the liquid is equal to atmospheric pressure. Bubble Point: -It is a temperature at which first bubble of vapour is formed.

4. When does liquid boil? When the vapour pressure of the liquid is equal to atmospheric pressure at that time liquid is boil.

5. Define: - Volatile Liquid. It is a tendency of a liquid to vaporize.

6. Acetone and water out of this which is more volatile and why? Acetone is more volatile than water because of boiling point of acetone (56.7 °C) is low compa re to boiling point of water (100° C)

7. What is the Relative Volatility? It is a ratio of concentration of more volatile component in vapour phase to liquid phase is called Relative Volatility 8. What is important of Relative Volatility? For separation of liquid mixture using distillation, Relative volatility should be more than 1.

9. Why is Reflux done in distillation column? and Define Reflux Ratio. For Increasing product purity. Reflux: -It is amount of distillate which is resend to distillation column is known as a reflux. Reflux Ratio: -Reflux ratio is the ratio of the portion of the overhead liquid product from a distillation column that is returned to the upper part of column to the portion of liquid collected as distillate.

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10. What is effect of reflux ratio on the no. of plate required in distillation column?

At high reflux ratio no. of plate required less (Small column height) and at low reflux ratio no. of plate required more (Large column height).

11. Define Distillation, Simple distillation, Steam distillation, vacuum distillation, Azeotropic distillation, Extractive distillation and Fractional distillation?  Distillation: – Distillation is unit operation in which liquid mixture is separated based on their boiling point difference and relative volatility by means of thermal energy.

 Simple Distillation: – when the boiling point difference of two liquid in mixture is high then we can use simple distillation. Ex: – A mixture of acetone (B.P. – 57 ˚c) & water (B.P. – 100 ˚c) can be separated by simple distillation because boiling point difference is high.

 Steam distillation: – Steam distillation is used for - Separating high boiling components from Nonvolatile impurities by using steam. - For separating high boiling fraction where there are chances of decomposition of material at high temperature.

 Vacuum Distillation: – It is the type of distillation in which the liquid mixture is to be distilled out in the vacuum which is less than the atmospheric pressure.  Azeotropic Distillation: – (When Boiling point difference is very low)

In Azeotropic distillation a third component called entrainer is added to the mixture which forms a new low boiling azeotrope with one of the components which is distilled out first.

Ex – Acetic acid (B.P. – 115 ˚c) and water (B.P. - 100 ˚c) mixture, the butyl acetate (B.P. – 90 ˚c) is added as entrainer and it forms azeotrope with water in the mixture. Water and butyl acetate is distilled out while acetic acid is remain as residue.

 Extractive Distillation: - Also used when boiling point difference is very close

In Extractive distillation solvent is added which alter the relative volatility of the original components, thus permitting separation.

Ex – In Toluene (B.P – 111 ˚c) and Iso-octane (B.P. – 100 ˚c) liquid mixture, phenol (B.P. – 182 ˚c) is added as solvent, Iso-octane is removed as distillate and toluene and phenol removed as residue.

 Fractional Distillation: – It is used for separating more than two components from the liquid mixture

Ex – Crude oil

12. What is principle of vacuum distillation & Define Vacuum?

Vacuum is pressure less than atmospheric pressure, when it is applied at that time liquid boils before its boiling point.

Vacuum: – Pressure below the atmospheric pressure is called vacuum.

13. MSDS (Three or Four sentences)

MSDS – Material safety data sheet. It includes…

- Product information - Hazard information - Fire and explosive hazardness - First aid measure - Safety information

14. State Boyle law, Charles law, Gay-Lussac law? Boyle law: – For a fixed mass of gas at constant temperature, the volume is inversely proportional to the pressure.

V α 1/p T – Constant

Charles law: - For a fixed mass of gas at constant pressure, the volume is directly proportional to the temperature.

V α T P – Constant

Gay-Lussac law: - For a fixed mass of gas at constant volume, the pressure is directly proportional to the temperature.

P α T V – Constant

15. What is the value of Avogadro number & It’s Significance?

Avogadro number is the defined as the number of particle (Molecule, atoms, compound) per moles of substance.

Value of Avogadro number is 6.022 × 1023 Mol-1, and expressed as the symbol NA.

16. Define Freezing point? Write the Freezing point of Methanol, Ethanol, Benzene, Acetone, Toluene?

Freezing point: – The freezing point is the temperature at which a liquid changes to a solid when cooled.