Activity 1.
Your teacher will guide you how to measure the volume of liquids using the other apparatuses.
Aim: To measure volume of liquids using different apparatus
Materials: pipettes, burettes, measuring cylinders, water, beakers.
Procedure
1. Pour some water into a graduated measuring cylinder with a capacity of 100 cm3. Add the water, one drop at time, up to a 25-cm3 mark.
2. While adding water, position yourself at eye-level with the mark on the cylinder. This
will enable you to obtain the most accurate measurement. To simplify the work of reading the level of the water, you may use coloured water.
3. Select a volumetric flask measuring 50 cm3. Pour the water into the flask until it reaches
the mark on the flask‟s neck.
4. Position yourself at eye-level with the mark. You will obtain the most accurate reading
when the mark appears straight rather than elliptical. To obtain this, put a flask on a flat table.
5. Add water one drop at a time. Do so until the bottom of the curved surface of the water
exactly matches the mark on the flask.
Activity 2.
Aim: To measure the masses of solid substancesMaterials: chemical, electronic or spring balance, watch glasses, various substances such as
sand, sugar, salt, flour, stones, fruits.
Procedure
1. Put an empty watch glass on the weighing balance. Note down its mass. Record this as
mass M1.
2. Place the various items you have on the watch glass, one item at a time. Note down the
mass. Record this as M2.
Note: to obtain the mass of an object, we subtract the mass of an empty watch glass from the mass of the watch glass and the substance. That is, M2 - M1.
Activity 3.
Investigation of the compressibility of solids, liquids and gases
Procedure1. Take three new syringes and fill them with sand, water and air respectively (figure 5.1).
2. Try to push in the end of each syringe.
3. Observe what happens.
Observation
Which of the substances under investigation can compress into a smaller volume?
Findings
You should have found that a solid (sand) and a liquid (water) cannot be compressed but a gas (air) is easily compressed.
Procedure;
1. Put a small spot of the water-soluble ink onto a strip of filter paper as shown in figure below
2. Place the filter paper in a beaker of water. Make sure the level of the water is below the level of the ink spot.
3. Leave the filter paper until the water has risen to the top of the paper.
4. Remove the paper and allow it to dry.
5. Note the colors the ink contains.
Observation
As the solvent (water) moves up the paper, the dyes are carried with it and begin to separate. They separate because they have different solubilities in water and are absorbed to different degrees by the filter (chromatography) paper. As they rise, they are gradually separated.
Findings
The different colours of the ink make a pattern of colours formed during the process of chromatography. This pattern of colours is called a chromatogram.
1. Put the solution into a separating funnel as shown in figure (a).
2. Add ethoxyethane. This forms a layer on top of the solution (b). The ethoxyethane is
called the extracting solvent.
3. Stopper the separating funnel and shake well figure (c). The iodine, which is more
soluble in the ethoxyethane, passes into the ethoxyethane layer. The sodium chloride remains in
the water layer.
4. The water layer is run off into a beaker followed by the ethoxyethane layer into another
beaker (Caution: Remove the stopper before opening the tap).
5. The ethoxyethane is then evaporated off by simple distillation. Similarly, the water layer
can be evaporated to yield sodium chloride.
The solvent extraction works on two principles:
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