core practical Flashcards
Describe distillation
The salt solution is placed into a flask and heated until it boil.
The water turns into a gas but the salt stays behind in the flask.
The steam passes into the condenser. The condenser is a tube that is surrounded by a layer of cold water. This cools the steam, which turns it back into a liquid.
The distillate is pure water
describe filtration
put the solution in an evaporating basin
warm the solution by placing the evaporating basin over a boiling water bath
stop heating when crystals begin to form around the edge of the basin
After the remaining solution has cooled down, pour the excess liquid away (or filter it). Dry the crystals using a warm oven or by patting them with filter paper.
describe how to do paper chromatography
Method draw a pencil line across the chromatography paper, 1-2 cm from the bottom use a pipette or capillary tube to add small spots of each ink to the line on the paper place the paper into a container with a suitable solvent in the bottom allow the solvent to move through the paper, but remove the chromatogram before it reaches the top
describe neutralization
Use a measuring cylinder to add dilute hydrochloric acid to a beaker.
Dip a clean glass rod into the contents of the beaker. Use it to transfer a drop of liquid to a piece of universal indicator paper on a white tile. Wait 30 seconds, then match the colour to a pH colour chart. Record the estimated pH.
Add a level spatula of calcium hydroxide powder to the beaker.
Stir thoroughly, then estimate and record the pH of the mixture (as in step 2).
Repeat steps 3 and 4 until there are no more changes in pH.
describe electrolysis
Pour the solution being electrolyzed into the beaker. Insert the carbon rods into the solution. The rods must not touch each other. Attach crocodile leads to the rods. Connect the rods to the dc (red and black) terminals of a low-voltage power supply (4V). Look at both electrodes and record your observations.
describe how to measure rate of reaction
Support a gas syringe with a stand, boss and clamp.
Using a measuring cylinder, add 50 cm3 of dilute hydrochloric acid to a conical flask.
Add 0.4 g of calcium carbonate to the flask. Immediately connect the gas syringe and start a stop clock.
Record the time for every 10 cm3 of gas produced.
When the reaction is complete, clean the apparatus as directed by the teacher.
Repeat steps 1 to 5 with different concentrations of hydrochloric acid.
describe how to do titration
Use the pipette and pipette filler to add the alkali to a clean conical flask.
Add a few drops of indicator and put the conical flask on a white tile.
Fill the burette with acid and note the starting volume.
Slowly add the acid from the burette to the alkali in the conical flask, swirling to mix.
Stop adding the acid when the end-point is reached (when the indicator first permanently changes colour). Note the final volume reading.
Repeat steps 1 to 5 until you get concordant titres (see step 1 in the Analysis). More accurate results are obtained if acid is added drop by drop near to the end-point.
