Appendix 5
- Task
- Practice Exercises
In the Chemistry Laboratory #
Safety precautions:#
| Avoid inhaling vapours. |
| Avoid skin contact with the reactants and products. Wear gloves. |
| Ensure burettes are filled when the top of the burette is below eye level. |
| Ensure the delivery tube does not become blocked. |
| Ethanoic acid will sting if it gets into cuts in the skin. |
| Pay attention to the hazard warnings on the tubs and bottles of unknown substances. In particular, if anything is marked flammable, do not use anywhere near a lit Bunsen burner. If heating a flammable substance is required, then it must be heated by standing it in a beaker of hot water. |
| Phenol is corrosive and toxic. |
| Potassium nitrate is oxidizing. |
| Sulfuric acid is an irritant. |
| The product of the distillation process is flammable. |
| This procedure requires the use of a working fume cupboard. |
| Tie long hair back. |
| Unknown inorganic solids must be regarded as harmful. |
| Unknown organic liquids must be treated as harmful and flammable. |
| Wear a lab coat,gloves and use eye protection. |
| Zinc sulfate is harmful. |
Procedure:#
| The verb: | Translation: | Example: |
|---|---|---|
| acidify | подкислять | Acidify each mixture with dilute nitric acid and then add 5 drops of silver nitrate solution. |
| add | Add two or three drops of phenolphthalein to the conical flask. Add approximately 20 cm3 of sodium hydrogen carbonate solution to the separating funnel. Swirl the funnel. Add four drops of methyl orange indicator to the conical flask. Add four drops of methyl red indicator to the mixture. Add sulfuric acid to the small beaker. | |
| calculate | Calculate a value of Ka for ethanoic acid. Calculate the concentration of the original solution of hydrochloric acid. Calculate the mean titre using your two concordant results. Calculate the number of moles of sodium hydroxide that were contained in your mean titre. | |
| compare | Compare your value for the mass of iron with the information from the supplier about the composition of each iron tablet. | |
| carry out | Carry out your experiments to identify substances A–D. Pay particular attention to the management of safety. | |
| change | Change the subject of an equation. | |
| clean | Clean the strips of zinc and copper using sandpaper. | |
| collect | Collect the fraction boiling between 50 °C and 52 °C. | |
| continue | Continue to conduct titrations until you have two concordant titres. | |
| crush | толочь | Crush the iron tablets using the pestle and mortar. |
| dissolve | Dissolve the precipitate formed by adding ammonia solution drop-wise until the precipitate just dissolves. | |
| describe | Describe the pattern shown in your results. | |
| draw | Draw a straight line of best fit – this line must pass through the origin. Draw an energy level diagram for each reaction. | |
| decant | фильтровать | Decant the organic liquid into a 50 cm3 pear-shaped (or round-bottomed) flask. |
| deduce | Deduce the order of the reaction with respect to iodide ions. | |
| empty | Empty the crushed tablets into the small beaker and reweigh the weighing boat. | |
| explain | Explain why the reactions... | |
| filter | процеживать | Filter the solution (to remove any undissolved solids) into the volumetric flask. |
| fill | заполнять | Fill a burette with sodium hydroxide solution. |
| hold | Hold the wire at the edge of a hot Bunsen burner flame and observe the colour. | |
| heat | Heat the mixture by standing the test tube in a beaker of hot water. | |
| join | Join the two metal strips with a voltmeter, using the connecting wires and crocodile clips. | |
| look up | Look up how to carry out the flame test to identify metal cations. | |
| make | Make an electrical connection between the two beakers by joining them with a strip of filter paper. Make the solution up to the mark with deionized water. Make up to the mark with distilled/deionized water. | |
| measure | Measure the temperature of the acid. Measure the time taken for a precipitate to appear. As soon as the solution becomes cloudy, stop the stop clock. | |
| mix | Mix aqueous propanone with sulfuric acid in a beaker | |
| note | Note the exact time at which the sodium hydrogencarbonate is added. | |
| pipette | Pipette 25.0 cm3 of 0.1 mol dm−3 ethanoic acid solution into a 250 cm3 conical flask. | |
| pour | Pour this into the mixture prepared in steps 1 and 2. | |
| place | Place 10 drops of each liquid into three separate test tubes. Place 30 cm3 of ethanoic acidin the boiling tube. Place approximately 0.05 g of calciumcarbonate in a test tube. Place your pure product in a labelled sample tube. | |
| plot | Plot a graph of mass of calcium carbonate (on the x-axis) against volume of carbon dioxide collected (on the y-axis). | |
| prepare | Prepare your apparatus for the titration. | |
| record | Record the electrode potential of system. Record the pH of the solution after the second addition of ethanoic acid. Record your results in a table. Record your results in an appropriate format. | |
| repeat | Repeat the experiment six more times. Repeat the titration until concordant results are obtained. | |
| reweigh | Reweigh the test tube that had contained the calcium carbonate. | |
| rinse | промывать | Rinse the beaker with more sulfuric acid and add the washings to the volumetric flask. |
| run off | Run off and discard the lower layer. Ensure none of the aqueous layer remains in the tap. Run off the organic layer into a small conical flask. | |
| remove | Remove the bung from the boiling tube and tip the calcium carbonate into the boiling tube. | |
| replace | Quickly replace the bung in the boiling tube. | |
| set up | Set up the datalogger to read the pH. Set the apparatus up as shown in the diagram. Set up a zinc half-cell into a separate 100 cm3 beaker. | |
| start | Start the stop clock the moment you add iodine solution. | |
| stop | Stop the clock when a blue colour appears in the beaker and note the time taken. | |
| stopper shake | встряхнуть | Stopper and shake the beaker to mix well. |
| stir | Stir to dissolve as much of the tablets as possible. | |
| scoop | Scoop approximately 2.5 g of sulfamic acid into the test tube. | |
| swirl | покручивая | Gently swirl the contents of the flask very gently. Swirl until it has dissolved. Swirling will cause the pink colour to fade and disappear – if the pink colour persists for 5 seconds or more, then the end point has been reached. |
| should | The burette should contain the sodium hydroxide solution and the conical flask should contain the dilute hydrochloric acid solution. You should describe in detail how you would carry out the experiment and the results you would expect. | |
| subtract | Subtract the mass of the empty weighing bottle from the first reading to give exact of mass actually added. | |
| titrate | Titrate the ethanoic acid with sodium hydroxide solution until the mixture just turns pink. | |
| tabulate | Tabulate your results for Part 1 and Part 2. | |
| transfer | перемещать | Transfer the crushed tablets to a weighing boat and measure their combined mass. Transfer the reaction mixture to a separating funnel. |
| use | Use logarithms in relation to quantities that range over several orders of magnitude. Use a kettle and a beaker to prepare a water bath with a temperature of 75 °C. Use the pipette to transfer 25.0 cm3 of the hydrochloric acid solution into the volumetric flask. Use your graph to find the volume of carbon dioxide. Using a pipette, withdraw a 10 cm3 sample of the mixture and transfer it to a conical flask. | |
| warm | Warm the mixture in a water bath. | |
| wash out | Wash out the 250 cm3 volumetric flask with distilled water. | |
| write | Write the equation for the ionisation of a weak acid HA in water. | |
| withdraw | Using a pipette, withdraw a 10 cm3 sample of the mixture and transfer it to a conical flask. | |
| work out | Work out the rate for each of these concentrations. | |
| weigh | Weigh the test tube and its contents accurately. Weigh an empty test tube. Weigh the test tube and its contents accurately. | |
| write | Write a plan for the safe conduct of a flame-test experiment. |
Describing reaction properties:#
| The verb: | Translation: | Example: |
|---|---|---|
| behave (itself) | Folic acid behaves as a weak acid – it can be represented as HA. | |
| bubble | Bubble any gas evolved through limewater. | |
| bleach | Chlorine bleaches damp litmus paper. | |
| give (colour) | Carbon dioxide gives a white with limewater. | |
| liberate | Nitrite liberated on heating with OH-(aq) and Al foil. Sulfite liberated with dilute acids. | |
| pop with | Hydrogen “pops” with a lighted splint. | |
| relight | Oxygen relights a glowing splint. | |
| turn from ...to | Sulfur dioxide turns acidified aqueous potassium dichromate (VI) from orange to green. |