Separation of components of mixtures - class-VII

Passing the mixture through water can separate the mixture of ammonia and hydrogen. Ammonia being highly soluble dissolves in water while hydrogen passes out as gas.

Mole fraction of A in solution containing A and B $=\dfrac {n _A}{n _A+n _B}=\dfrac {mole}{mole}$ which cancels out. 

Light A gives a more cooling sensation than liquid B means liquid A is early vaporised than liquid B. Thus, liquid A has less B P and lower latent heat of vaporisation than that of liquid B.

A liquid reaches its boiling point when its vapor pressure is equal to the atmosphere around it.

Diffusion refers to a process by which molecules intermingle as a result of their kinetic energy of random motion. Molecules of gases are in constant motion and make numerous collisions with the partition.

By determining the boiling point of the liquid and comparing it with a colourless liquid, we can confirm whether it is pure water or not

Gas mixtures can be effectively separated by synthetic membranes made from polymers such as poly-amide or cellulose acetate, or from ceramic materials. It can be used for separation of nitrogen or oxygen from air. Helps in Recovery of hydrogen in oil refinery processes. Also used in Separation of methane from the other components of bio gas.

Lighter gases diffuse more rapidly through porous component.

The most important advantage of liquefying gases is that they can then be stored and transported in much more compact form than in the gaseous state. Two kinds of liquefied gases are widely used commercially for this reason, liquefied natural gas (LNG) and liquefied petroleum gas (LPG).

To separate a liquid-liquid mixture having different boiling points, fractional distillation can be used.

A mixture of two gases can be separated by diffusion, liquefaction and solubility in a solvent.

Gas separation is an important unit operation employedwidely throughout the chemical industries. Gas separation in membranes occurs due to differences in permeabilities of the species flowing through the membrane.

In a box with a semi-permeable membrane containing a mixture of two gases, the lighter molecules will pass out of the container more rapidly than the heavier molecules. The gas leaving the container is somewhat enriched in the lighter molecules, while the residual gas is somewhat depleted. A single container wherein the enrichment process takes place through gaseous diffusion is called a diffuser.

Gaseous diffusion is unlikely to be the preferred technology of a proliferator due to difficulties associated with making and maintaining a suitable barrier, large energy consumption, the requirement for procuring large quantities of specialized stage equipment, large in-process inventory requirements, and long equilibrium times.

In a box with a semi-permeable membrane containing a mixture of two gases, the lighter molecules will pass out of the container more rapidly than the heavier molecules. The gas leaving the container is somewhat enriched in the lighter molecules, while the residual gas is somewhat depleted. 

Water and oil are immiscible and they form two separate layer, oil have less density than water, so it floats on the water surface so, the water and oil layer can easily be separated by the separatory funnel.

Fractional distillation is a process of separation of mixtures based on the difference in their boiling points.

Distillation and evaporation enables pure water to obtained from seawater,

Procelain chips are added to the mixture for two reasons: to prevent the superheating of liquid and to make the distilling flask more stable.

Due to difference in degree of adsorption of gases by charcoal, a mixture of noble gases can be separated by adsorption double walled tube containing coconut charcoal.

Due to the increase in kinetic energy at higher temperature, the solvent milecules effectively break the solute molecules that are held together by intermolecular forces.

An azeotropic mixture cannot be separated into its components by fractional distillation because, when an azeotrope is boiled, the vapor has the same proportions of constituents as the unboiled mixture. The statement is true  

Distillation is a method of separating mixtures based on differences in their volatiles in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction. Water is distilled to remove impurities, such as salt from seawater. 

Individual gases can be separated from a gaseous mixture of $O _2$, $H _2$ and $CO _2$ passing through $KOH$ solution, then diffusion. $KOH$ will absorb $CO _2$ gas. $O _2$ and $H _2$ have different rates of diffusion as they have different molecular weights.

The mixture of carbon monoxide and carbon dioxide can be separated by passing the mixture through water under high pressure or through concentrated NaOH solution.Also mixture can be separated by passing it through ammonical cuprous.

To separate a mixture of two or more miscible liquids for which the difference in boiling points is less than 25 K, fractional distillation process is used.

Chromatography is a method of separation that works on adsorption. Different components of the mixture have different affinities for the stationary phase and the mobile phase. In other words, the extent of adsorption on the stationary phase, is different for different components of the mixture.

The two immiscible liquids having different densities can be separated by separating funnel.

Gaseous diffusion is based on Graham's law, which states that the rate of effusion of a gas is inversely proportional to the square root of its molecular mass. For example, in a box with a semipermeable membrane containing a mixture of two gases, the lighter molecules will pass out of the container more rapidly than the heavier.

Fractional distillation is a separation process for liquid-liquid mixture into its component parts, or fractions.
The separation depends on the difference in the  boiling point (usually 25 $^o$C at 1 atm) of individual components. The mixture is heated to a temperature at which one or more fractions of the compound will vaporize.   
For boiling point difference greater than 25 $^o$C, a simple distillation is used.

Membranes used in solubility based gas separation are inorganic, polymeric and hybrid membranes.
Microporous inorganic membranes are usually amorphous in nature and formed from metals, ceramics, or pyrolyzed carbon. The use of polymer membrane has generated an increasing interest in gas separation. Also different types of membrane has been used to enhance gas separation.

Porous and non-porous are two types of membrane.
They work through a different mechanism.
Highly selective nonporous membranes must be very thin to achieve reasonable capacities per unit area. This limits their mechanical strength.
Porous membranes typically contain larger voids than non-porous membranes which have interconnected pores significantly larger than the molecular diameters of gases passing through them.

Gas mixtures can be effectively separated by synthetic membranes made from polymers such as polyamide or cellulose acetate, or from ceramic materials.

 A gaseous mixture containing CO$ _2$ and CO can be separated by solvent extraction.
The mixture is passed through water.  CO$ _2$ dissolves in water whereas CO does not.

In a mixture of NH$ _3$ and H$ _2$, NH$ _3$ gets liquefied under pressure
Liquefaction of gases is the process by which a gas is converted to a liquid. In a mixture of NH$ _3$ and H$ _2$, NH$ _3$ gets liquefied under high pressure and H$ _2$ is left behind.
Note: NH$ _3$ has a higher value of the van der Waal's constant 'a' than $H _{2}$
Hence, NH$ _3$ is more easily liquefiable than H$ _2$.

Liquefaction is useful when one gas is easily liquefiable.
Liquefaction of gases is the process by which a gas is converted to a liquid by applying high pressure and low temperature. For example, oxygen normally occurs as a gas. However, by applying high pressure and by reducing the temperature, oxygen can be converted to a liquid.
Note:
In a mixture of NH$ _3$ and H$ _2$, NH$ _3$ gets liquefied under pressure
Liquefaction of gases is the process by which a gas is converted to a liquid. In a mixture of NH$ _3$ and H$ _2$, NH$ _3$ gets liquefied under high pressure and H$ _2$ is left behind.
NH$ _3$ has higher value of the van der Waal's constant 'a' than
Hence, NH$ _3$ is more easily liquefiable than H$ _2$.

Vapour Density for Sulphur dioxide is 32, for Nitrogen is 14, Carbon monoxide is 14 and ammonia is 8.5 .

Vapour density for ammonia is 8.5 while for chlorine is 35.5, HCl is 18.25 and oxygen is 16.

Magnetic separation and sublimation can be used to separate solid from solid. Crystallization is used to recover solid from liquid. Hence, none of the above methods is used for separation of liquid from liquid.

Gaseous diffusion works on the principle that molecules of a lighter isotope would pass through a porous barrier more readily than those of a heavier isotope.

Solubility-based gas separations for applications such as the removal of VOCs from air, in recent times have become important due to environmental and economic driving forces.The main objective is to obtain membranes that exhibit high permeability and high selectivity for the heavier species over the light gases.

$\displaystyle  2H _2 + O _2 \rightarrow 2H _2O$
2 moles of hydrogen will react with 1 mole of oxygen.
Volume is directly proportional to the number of moles.
4 ml of hydrogen will react with $\displaystyle  \dfrac {4 \times 1}{2}= 2$  ml of oxygen.
$\displaystyle  23-2 = 21 ml$  of oxygen will be left uncombined.

$\displaystyle  2H _2 + O _2 \rightarrow 2H _2O$
2 moles of hydrogen will react with 1 mole of oxygen to form 2 moles of water.
Volume is directly proportional to the number of moles.
4 ml of hydrogen will react with $\displaystyle  \dfrac {4 \times 1}{2}= 2$  ml of oxygen to form 4 ml of water.
$\displaystyle  23-2 = 21 ml$  of oxygen will be left uncombined.
Thus, after the mixture was sparked, 21 ml oxygen and 4 ml water are present.
Total volume of the gas after the mixture was sparked $\displaystyle  = 21 + 4 = 25 $ ml.

Gaseous diffusion is a technology used to produce enriched uranium by forcing gaseous uranium hexafluoride through semipermeable membranes. This produces a slight separation between the molecules containing uranium-235 and uranium-238. By use of a large cascade of many stages, high separations can be achieved. 

Distillation is a process of separating the component or substances from a liquid mixture by selective evaporation and condensation. Distillation may result in essentially complete separation (nearly pure components), or it may be a partial separation that increases the concentration of selected components of the mixture.

A cheque was suspected to be forged. Chromatography could be used to compare the various pigments in the different inks.  Here, different inks will have different affinity for  stationary phase  and solvent (mobile phase).

Fraction distillation is based upon the separation of components having very less boiling point difference, therefore components of crude oil and air can be separated using fractional distillation. In the air and in crude oil, the difference in boiling point of different components is very less. 

So $0.1=\dfrac{moles ,, of ,, B}{moles of A+B}$

The technique used for the separation of a mixture of a liquid and a gas is boiling. The gas is removed by application of heat.  With the increase in temperature, the solubility of gas decreases. The gas is collected separately

A mixture of hydrogen and chlorine can be separated by passage through a porous pot. This is because the diffusion of hydrogen more than that of chlorine in the porous pot. So, most of chlorine remains outside the pot.

The solubility of the gas is inversely proportiona to the $K _H$ value. Here, $Ar$ gas has the highest $K _H$ value so least solubility and $HCHO$ gas has the least $K _H$ value so highest solubility.

Alcohol and water are best separated from one another by distillation.