Chemistry required practicals

Question 1

What is the method for the making of salt from an insoluble oxide or carbonate?

Answer 1

1. Measure sulfuric acid into a measuring cylinder and pour it into beaker
2. Heat acid gently with bunsen burner
3. Add small amounts of insoluble base in excess
4. Filter using filter paper to remove excess
5. Pour the solution itno an evaporating basin
6. Evaporate with a water bath until crystals form
7. Leave basin in cool place for 24 hours
8. Gently pat crystals dry.

Question 2

What is the method for titration?

Answer 2

1. Use the pipette and pipette filler to put a strong alkali solution into the conical flask.
2. Clamp the burette vertically in the clamp stand. Leave enough room underneath for the conical flask.
3. Use the small funnel to carefully fill the burette with dilute strong acid. Before it completely fills
   put a small beaker underneath the tap, gently open it to allow acid to fill the tap, before closing
   again and filling the burette to the 0.00 cm3 line. Remove the funnel.
4. Put 5 drops of phenolpthalein indicator into the conical flask. Swirl the flask to mix and put
   under the burette on top of the tile. The contents of the flask will go pink.
5. Carefully open the burette tap so that 10 cm3 of strong acid slowly flows into the flask.
   Constantly swirl the flask when adding the acid. Then add the acid drop by drop until you see a
   permanent colour change from pink to colourless in the flask.
6. Shut tap immediately.
7. Read the burette scale carefully and record the volume of acid you added

Question 3

What is the method for electrolysis

Answer 3

1. Pour ionic solution into the beaker.
2. Add the petri dish lid and insert the carbon rods through the holes. The rods must not touch
   each other.
3. Attach crocodile leads to the rods. Connect the rods to the dc power supply
4. Switch on power supply
5. Look at both electrodes and record observations
6. Use forceps to hold a piece of blue litmus paper in the solution next to the anode (positive
   electrode) and identify the element?

Question 4

What is the method for variables that affect temperature change in chemical reactions.

Answer 4

1.Measure 30 cm3 dilute acid and put it into the polystyrene cup.
2. Stand the cup inside the beaker.
3. Use the thermometer to measure the temperature of the acid.
4. Measure 5 cm3 alkali solution.
5. Pour the alkali into the polystyrene cup. Fit the lid and gently stir the solution with
the thermometer through the hole.
6. Look carefully at the temperature rise on the thermometer.
7. When the reading on the thermometer stops changing, record the highest temperature
reached in the table.
8. Repeat steps 4–7 to add further 5 cm3 amounts of acid to the cup each time,
recording your temperature reading in the results table.
9. Repeat until a maximum of 40cm3 of alkali has been added.
10. Wash out all the equipment and repeat the experiment for your second trial.

Question 4

What is the method for how concentration of an acid affect the rate of reaction?

Answer 4

1. Measure 50 cm3 of 1.0 mol/dm3 acid using one of the measuring cylinders. Pour
   the acid into a conical flask.
2. Fit the bung and delivery tube to the top of the flask.
3. Half fill the trough or bowl with water.
4. Fill the other measuring cylinder with water. Make sure it stays filled with water when you
   invert it into the water trough and that the delivery tube is positioned correctly.
5. Repeat steps 1–6 using 1.5 mol/dm3
   hydrochloric acid.

Question 4

What is the method for chromatography?

Answer 4

1. Use a ruler to draw a horizontal pencil line 2 cm from the bottom short edge of the
   chromatography paper.
2. Mark five pencil spots at equal intervals across the origin line.
3. Use a glass capillary tube to put a small spot of each colouring A, B, C and D on four of the
   pencil spots. Use a different tube for each colouring. Use the fifth tube to put a small spot of
   the unknown mixture U on the fifth pencil spot.
4. Pour water into the beaker to a depth of no more than 1 cm.
5. Clip the top short edge of the chromatography paper to the wooden spill.
6. Carefully rest the wooden spill on the top edge of the beaker. The bottom edge of the paper
   should dip into the water solvent.
7. Wait for the water solvent to travel at least three quarters of the way up the paper.
8. Carefully remove the paper from the beaker. Draw the solvent front line.
9. Hang the paper up to dry thoroughly.
10. Measure the distance in mm between the two pencil lines. This is the distance travelled by the
    water solvent.
11. For each of food colour A, B, C and D measure the distance in mm from the start line to the
    middle of the spot.

Question 4

What is the method for the flame test.

Answer 4

1. Pour about 1 cm depth of each of the labelled ionic solutions into five test tubes in the rack.
2. Dip the nichrome wire into the first solution. Then hold the tip of the wire in a blue Bunsen
   burner flame.
3. Clean the wire carefully.

Question 4

What is the method for the carbonate test.

Answer 4

1. Pour about 1 cm depth of each of the labelled solutions into five test tubes in the rack.
2. Place 1 cm depth of limewater in a sixth test tube.
3. Add 1 cm depth of dilute hydrochloric acid to each solution in turn.
4. Only if you see bubbles, quickly use the teat pipette to transfer the gas produced to the
   limewater.
   5.take several pipettes of the gas coming off at the surface to get a change in
   the limewater.

Question 5

What is the method for the sulfate test.

Answer 5

1. Pour about 1 cm depth of each of the labelled solutions into five test tubes in the rack.
2. Add a few drops of dilute hydrochloric acid to each solution. Then add 1 cm depth of barium
   chloride solution.

Question 6

What is the method for the Halide test?

Answer 6

1. Pour about 1 cm depth of each of the labelled solutions into five test tubes in the rack.
2. Add a few drops of dilute nitric acid to each solution. Then add 1 cm depth of silver nitrate
   solution.