STANDARD SEPARATION TECHNIQUE

 

Week:                                                                                      Date:                                                   

Period:                                     Duration: 40MIN. EACH                                   Average age of learners: 15 YEARS

Subject:                 CHEMISTRY                                                                           Class: SS ONE

Topic:                      STANDARD SEPERATION TECHNIQUE

Sub topic: principles behind the choice of separating techniques and different apparatus

Reference materials:

(1) ESSENTIAL CHEMISTRY, TONALD PUBLISHERS, I. O ODESINA

(2) NEW SCHOOL CHEMISTRY, AFRICAN FIRST PUBLISHERS, OSEI YAW ABABIO

(3) INTERNET

Instructional materials: Separating funnel, funnel, filter paper, sand and salt.

Entry behavior: The students have been familiar with some common element.

Behavioural objective: At the end of the lesson the students should be able to:

PERIOD I

i.                     define separating technique.

ii.                    State the principle behind the choice of separating techniques

iii.                  Explain decantation

PERIOD II

i.                     Explain  filtration

ii.                    Explain evaporation and crystallization

PERIOD III

i.                     Explain fractional distillation

ii.                    Explain simple distillation and fractional distillation

 

 

STANDARD SEPERATION TECHNIQUE

PERIOD I

STEP I: The teacher defines separating technique

Separation techniques are those techniques that can be used to separate two different states of matter i.e a mixture involves only physical means and this depends on the physical properties of the components of that mixture. Such separation techniques include filtration or evaporation.

 STEP II: The teacher states the principle behind the choice of separating technique

The principles behind the choice of separating techniques are: size of particles; solubility of the substance in solvent; immisible liquid; sublimation; boiling point; magnetic properties, rate of movement, miscibility etc

STEP III: The teacher explains decantation

Decanting: A crude way of separating insoluble solids from liquids, as the liquid is poured away and collected in another container. Note that the insoluble solid should be able to settle down on standing and this method is not effective for obtaining clear liquid from the mixture especially when the insolublesolid is very fine and light..

 

 

EVALUATION: The teacher evaluates the students by asking the following questions.

i.                     Explain separating techniques

ii.                    State the principle behind the choice of separating techniques

iii.                  Explain decantation

ASSIGNMENT: The students are to read about filtration, evaporation and crystallization.

PERIOD II

STEP I: The teacher explains filtration

2.  Filtration: Separation of solids or groups of solids from the liquid in a mixture, using a medium through which the liquid can pass. The medium which we are using over here is the filter paper. The filter paper is folded and placed onto the filter funnel.

The liquid-solid mixture is poured onto the filter paper. Using a filter paper with pores of a smaller size than the solid particles (and is larger than the size of the liquid molecules), the liquid (or solvent) should pass through the filter paper, and is collected by a collection container placed at the bottom of the filter funnel. liquid that passes through the filter paper is called the filtrate while the solid left on the filter paper is called the residue. Industries such as water purification plants and breweries use filtration to remove solids particles from liquids.

STEP II: The teacher leads the students to separate mixture of sand and salt using filtration method

STEP III: The teacher explains evaporation

 Evaporation: In the case which we do not need to collect the solvent. The solvent is boiled off and escape into the air while the solute is left behind in the holding container. Note that this method is not suitable for use on solutes which can decomposed by heating (e.g. Copper II sulfate).

3.                                                                                               4.

 

STEP IV: The teacher explains crystallization

4. Crystallisation: This is used to separate salts or solutes, which decompose easily on heating, from their solutions. Crystallization is also a chemical solid-liquid separation technique, in which mass transfer of a solute from the liquid solution to a pure solid crystalline phase occurs.

Crystallization is based on the principles of solubility: compounds (solutes) tend to be more soluble in hot liquids (solvents) than they are in cold liquids. If a saturated hot solution is allowed to cool, the solute is no longer soluble in the solvent and forms crystals of pure compound. Impurities are excluded from the growing crystals and the pure solid crystals can be separated from the dissolved impurities by filtration. Some of the salts obtained from crystallization include:

Copper(II) tetraoxosulphate(VI)-pentahydrate

Copper(II) trioxonitrate(V)-trihydrate

Crystallization is used in industries where purity of the product is important as in the manufacture of drugs in sugar production.

EVALUATION: The teacher evaluates the students by asking the following questions.

i.                     Explain filtration

ii.                    Explain evaporation

iii.                  What is the principle behind crystallization

PERIOD III

STEP I: The teacher explains fractional crystallization

5.  Fractional crystallization: This is used to separate two or more solid solutes which are present in the same solution in roughly equal amounts.

The process by which a chemical compound is separated into components by crystallization. In fractional crystallization the compound is mixed with a solvent, heated, and then gradually cooled so that, as each of its constituent components crystallizes, it can be removed in its pure form from the solution.

 STEP II: The teacher explains simple distillation

 6. Simple Distillation: To separate and collect solvent from a solution of solutes, or in a mixture of two different liquids (with different boiling points), with the use of heat.

The logic behind how simple distillation works is actually the same as that of evaporation. The only difference is that a closed neck container (distillation flask) is used to hold the mixture to be heated, with a opening/tube by the side (of the container) connected to a condenser. The setup for simple distillation should look something like this:

6.  7.

As the sea water mixture is heated, water boil and changes into water vapour gas. Since hot air rises and cold air sinks, the hot water vapour moves to the top of the flask and passes into the condenser.

The tubes on the condenser are attached to a water source, with the water flowing in through the lower end and flowing out through the higher end of the condenser. This creates a cooler surface for the hot water vapour to condense on. As the condenser is tilted downwards, towards the collecting container at the end of the setup, the condensed water flows and drips into the collecting container.

STEPIII: The teacher explains fractional distillation

7. Fractional Distillation: Used to separate miscible liquids with different but very close boiling point. This method is more efficient than simple distillation.

A fractionating column is introduced between the distillation flask and the condenser. The upper portion of the column, which is closer to the condenser, is cooler than the lower portion and hence, only gases with the same temperature as the upper portion are allowed to pass on to the condenser. On the other hand, the gases with higher boiling points will condense and flow back to the bottom into the distillation flask, and is heated into a gas again. At the end, liquid with the lowest boiling point will be the first to boil and hence the first to be distilled out and collected.

EVALUATION: The teacher evaluates the students by asking the following questions.

i.                     Explain  fractional crystallization

ii.                    explains fractional distillation

iii.                  differentiate between distillation and fractional distillation

ASSIGNMENT: The students are to draw the diagram of fractional distillation

Comments

Post a Comment

Popular posts from this blog

POST HARVESTING PROCESSES

CHAPTER TWELVES POST HARVESTING PROCESSES 12.1             CONCEPTS AND PHILOSPHY OF POST HARVEST TECHNOLOGY Post-harvest fisheries entails all steps, process and or activities immediately after catch handling and transportation processing and distribution of fish and fishery product where if control is not applied post-harvest losses will occur.         Post –harvest fish losses are a major concern and occur in most fish distribution chains throughout the world. Not only do losses constitute lost income to fishers, processors and traders, they also contribute food insecurity i.e a loss of fish means less fish available for the consumer. POST HARVEST PROCESSES:         Fish are highly perishable. A central concern of fish processing is to prevent fish from deteriorating . Causatic factors of fish spoilage 1. High moisture content.   ...
Read more

NICOM SAT 1

TOPIC: - NICOM-SAT 1    INSTRUCTIONAL MATERIALS: -         Satellite dish REFERENCES BOOK: -     1.      FARINDE O. E e tal, ESSENTIAL PHYSICS FOR SSS, Tonad Publishing Limited. 2.      M. W. ANYAKOHA (2011), NEW SCHOOL PHYSICS FOR SENIOR SECONDARY SCHOOLS, Africana first publishers.    3.      INTERNET PREVIOUS KNOWLEDGE: -     Students have been taught Niger-sat 1 INSTRUCTIONAL OBJECTIVES: - At the end of the lesson students should be able to: - 1.        Explain the concept of NICOM-SAT 1 2.        State the features of NICOM-SAT 1 3.        Uses of NICOM-SAT 1 CONTENT: - NICOM- SAT 1 NigComSat-1 is a Nigerian Communication Satellite. It was launched on 14 may, 2007 in China by China Great Wall Industry...
Read more

FISH SEED PRODUCTION

CHAPTER THIRTEEN FISH SEED PRODUCTION BROOD STOCK SELECTION             Brood stock means a group of sexually mature individuals of a culture species that is kept separate for  breeding purpose. 13.1     DIFFERENCES  BETWEEN MALE  AND FEMALE SEXUALLY MATURED FISHES             Male and female breeders may be easily differentiated by the shape of the body and the relative position of genital papilla. In females, the body is plump and the genital opening is situated above the genital papilla. In males, the body is slender and the genital opening is found behind the genital papilla. External signs of the brood stock A male brood stock will release milt under a slight abdominal pressure: Its belly is not blown up but rather slim; it sometimes has callosities on the head. A female brood stock has a well-rounded and soft  or semi...
Read more