Is Matter Around Us Pure? Blog 9

IMPORTANT MESSAGE FROM THE PRINCIPAL BRO. MIRANDA

https://www.youtube.com/watch?v=Nu7x_LMVrAM



(NOTE: HOLIDAY HOME WORK BLOG WILL BE PUBLISHED IN ZERO PERIOD)

Hello Learners,

Let us continue from the previous blog..

NOTE: Assignment based on this chapter will be published in next period.

(F) How can we separate a mixture of two miscible liquids?

Distillation: It involves conversion of a liquid into vapors by heating followed by condensation of the vapours thus produced by cooling.

https://www.youtube.com/watch?v=gJOLCpxZ9eI

(Draw this diagram in your chemistry notebook)

Principle: The separation of the liquid mixture into individual components can be achieved at their respective boiling points; the more volatile component distills over first while the less volatile components distills over afterwards.

Activity 2.8 asks us to separate a mixture of acetone and water using the distillation method.

Observation: Acetone is a volatile liquid. It easily vaporises on heating. On cooling, acetone again converts into its liquid form. Here we receive pure acetone in the beaker.

Explanation:

The distillation is the separation of two or more components from the mixture for volatile compounds. In this method, we employ the difference in the boiling point of different compounds. A compound with low boiling point evaporates fast. We collect these volatile compounds using condenser.

With the thermometer, we control the temperature so that we receive only one compound in the condenser.

This is a costly method as it requires enormous water to cool the condenser and costly setup. We use it only in the separation of precious products where we need all the components; like the perfume industry, petroleum refinery, some distilled beverage, in treating water salinity.

In general, purpose where the component is not costly, we use simple boiling and let the water escape.

https://www.youtube.com/watch?v=J1FjIRWVwTM

Application: 1. A mixture of ether (B.P. 308 K) and toluene (BP 384 K)

2.       A mixture of hexane  (BP 342 K) and toluene (BP 384 K)

3.       A mixture of benzene (BP 353 K) and aniline (BP 457 K) or nitro benzene (BP 483 K)

https://www.youtube.com/watch?v=mP4Hgui-g6U

Fractional Distillation

Principle: If the boiling points of the two miscible liquids of the mixture are very close to one another i.e. less than 25 K or so, the separation cannot be achieved by the simple distillation method. This is due to the reason that at the b.p. of the more volatile liquid of the mixture there will be sufficient vapours of the less volatile as well. As a result, both the liquids of the mixture will distill together and the separation cannot be achieved.

(Do not draw this diagram, it is for reference)

https://www.youtube.com/watch?v=PYMWUz7TC3A

Application: 1. The process of fractional distillation has been used to separate crude oil in petroleum industry into various useful fractions such as gasoline, kerosene oil, diesel oil, lubrication oil. Etc.

2. Fractional distillation of liquid air is used to separate gases of the air.

Factional distillation is used to separate a mixture of acetone (BP 329K) and methyl alcohol (BP 338K) from pyrollgneous acid obtained by destructive distillation of coal.

(G) How can we obtain different Gases from Air? 

Air is a homogeneous mixture of a number of gases such as nitrogen, oxygen, inert gases and carbon dioxides etc. These can be separated form each other by fractional distillation.

Principle: By increasing the pressure and decreasing the temperature, these can be be separated by fractional distillation. 

The flow diagram shows the steps of the process. The boiling point of nitrogen is the lowest -196℃ therefore it get distilled first of all, followed by argon with a boiling point of -186℃ while oxygen has the highest boiling point of 183℃.

         https://www.youtube.com/watch?v=sPIzSb073GI&t=25s

(Do not draw this diagram)

Home Assignment
1. Complete the notes in your chemistry note book.
2. Draw the diagram in your copy.
3. Do in-text questions in your note book.