Separation Techniques

Question 1

Filtration

Answer 1

Filtration is a process used to separate solid particles from a liquid or gas by passing the mixture through a filter medium that allows only the fluid (liquid or gas) to pass through while trapping the solid particles. Here’s how it typically works in steps:

Preparation of the mixture: A mixture containing solid particles and a liquid (or gas) is ready to be filtered. For example, this could be muddy water, where the water needs to be separated from dirt or other contaminants.

Selection of filter medium: Choose an appropriate filter medium (e.g., filter paper, mesh, or a membrane) based on the size of particles to be removed. The filter medium should have pores small enough to trap the solid particles but large enough to allow the fluid to pass through.

Setting up the filtration system: Place the filter medium in a suitable filtration apparatus. This could be a funnel with filter paper, a filtration flask, or a filter machine, depending on the scale of filtration.

Pouring the mixture: Slowly pour the liquid-solid mixture onto the filter medium. Gravity or vacuum pressure can be used to aid the process, depending on the type of filtration.

Separation of solids and liquid: As the mixture passes through the filter, the solid particles are trapped by the filter medium. The liquid (or gas) that passes through is called the filtrate, and the trapped solids are called the residue.

Collection of filtrate: Collect the filtrate (the liquid that has passed through the filter) in a clean container.

Disposal or cleaning of residue: The solid particles left behind on the filter can be discarded or cleaned, depending on the purpose of the filtration.

Completion: The filtration process is complete when all the liquid has passed through the filter, and the solid particles have been separated.

This process is widely used in various applications, such as water purification, chemical processing, and air filtration.

Question 2

Distillation

Answer 2

Here’s a simplified, step-by-step guide to distillation:

Step 1: Heating
Heat a mixture of liquids with different boiling points in a distillation apparatus.

Step 2: Vaporization
The liquid with the lowest boiling point vaporizes first, turning into steam.

Step 3: Separation
The vapor rises and separates from the remaining liquid.

Step 4: Condensation
The vapor passes through a condenser, cooling and turning back into a liquid.

Step 5: Collection
The distilled liquid (now separated from the original mixture) is collected in a separate container.

Question 3

Crystallization

Answer 3

Crystallization is the process by which a solid forms from a solution, where particles arrange themselves into a repeating pattern of atoms, molecules, or ions, creating a crystal lattice structure.

Step 1: Dissolving
Dissolve a substance in a solvent, like water or a chemical solution, to create a saturated solution.

Step 2: Cooling or Evaporation
Slowly cool or evaporate the solution, allowing the solvent to decrease.

Step 3: Nucleation
As the solution becomes supersaturated, tiny particles or “nuclei” form, attracting other particles.

Step 4: Crystal Formation
The particles continue to gather and arrange themselves into a crystal lattice structure.

Step 5: Collection
Once the crystal has formed, it can be filtered, washed, and collected.

That’s the basic crystallization process!

Question 4

Diatomic gases

Answer 4

Hydrogen (H2), nitrogen(N2) , fluorine(F2) ,oxygen(O2) , iodine(I2) , chlorine(Cl2) , bromine(Br2)

Question 5

Mnemonic

Answer 5

Have no fear of ice cold bears

Question 6

Heterogeneous vs homogeneous mixture diagram

Answer 6

Uneven and even distribution of particles

Question 7

What energy transfers occur during melting and during boiling in terms of the motion and relative positions of the water molecules

Answer 7

Here’s a concise summary:

Melting (Solid to Liquid):

• Absorb energy
• Increase molecular motion
• Break hydrogen bonds
• Change to liquid arrangement

Boiling (Liquid to Gas):

• Absorb energy
• Increase molecular motion
• Break intermolecular forces
• Change to gas state

Here’s what happens:

Melting (Solid to Liquid)

1. Absorption of energy: Water molecules gain energy (heat) from the surroundings.
2. Increased motion: Water molecules start vibrating more rapidly, gaining kinetic energy.
3. Breaking of hydrogen bonds: As energy increases, hydrogen bonds between water molecules begin to break, allowing molecules to move more freely.
4. Change in arrangement: Water molecules transition from a rigid, crystalline structure to a more random, liquid arrangement.

Boiling (Liquid to Gas)

1. Absorption of energy: Water molecules continue to gain energy (heat) from the surroundings.
2. Increased motion: Water molecules vibrate even more rapidly, gaining kinetic energy.
3. Breaking of intermolecular forces: As energy increases, intermolecular forces (like hydrogen bonds and van der Waals forces) between water molecules break, allowing molecules to escape into the air.
4. Change in arrangement: Water molecules transition from a liquid arrangement to a gas state, where molecules are widely spaced and free to move.

In both melting and boiling, energy is absorbed, and molecular motion increases. However, the key difference lies in the type of bonds broken: hydrogen bonds during melting, and intermolecular forces during boiling.

Question 8

Melting point

Answer 8

Of a pure substance is that fixed temperature at which the solid changes state to form its liquid

Question 9

The melting and boiling points depend on

Answer 9

Atmospheric pressure. The greater the pressure the lower the melting point and higher the boiling point.

Question 10

Freezing point

Answer 10

Of a pure substance is that fixed temperature at which the liquid solidifies to font the solid state. For pure substance it is the same temperature as the melting point

Question 11

Boiling point

Answer 11

Of a pure substance is that fixed temperature at which the liquid boils to form its vapor

Question 12

Boiling occurs in a liquid in an open vessel when

Answer 12

The vapor pressure is uqal to the atmospheric pressure acting on the liquid. Bubble of vapor form inside the liquid and vapor bubbles escape from the surface of the liquid when it is boiling. This happens because the pressure of the vapor equals the pressure or the surrounding air so the vapor molecules can break free of the liquid.

Question 13

Solid melting point and boiling point

Answer 13

Above and above room temperature

Question 14

Liquid melting and boiling point

Answer 14

Below and above room temperature

Question 15

Gas melting and boiling point

Answer 15

Btih below room temperature