OCR A level Chemistry Practical Exam Questions And Answers Verified 100% Correct

OCR A level Chemistry Practical Exam Questions And Answers Verified 100% Correct How does distillation work? -The different liquids in the mixture will have different boiling points. -The liquid with the lowest boiling point is the most volatile and will boil first. -The vapour moves out of the flask up into the other parts of the apparatus, leaving behind the less volatile components of the mixture. -When the vapours reach the cold condenser, they condense and become a liquid. -This liquid then drips into the collecting flask. How do you identify organic products after distillation? When preparing samples of organic liquid water may be obtained along side This will bring about the appearance of two liquid layers One will be organic one and one will be the aqueous one To identify which one is which you add some water to the mixture the larger that increases in size is the aqueous layer How do you separate organic layers and aqueous layers? Ensure tap of separating funnel is closed Pour liquid mixture in separating funnel and place a stopper on the top of the funnel and invert the contents Add water to see which layer gets bigger and this one is the aqueous layer Place a conical flask under the separating funnel, remove stopper and open tap until the whole of the lower layer has left the funnel Place a second conical flask under the separating funnel to collect the other layer The layers are now separated in the flasks Label which is which Why is titration used? Used to find a solution of unknown concentration by reacting it with another solution of known concentration What are the steps of a titration? Fill a burette with the acid of known concentration. Accurately measure an amount of the alkali using a calibrated pipette and pipette filler. Add the alkali to a conical flask with a few drops of a suitable indicator. Run in acid from the burette until the colour just changes showing that the solution in the conical flask is now neutral. Repeat the procedure adding the acid dropwise. How can you remove acid impurities? add aqueous sodium carbonate shake acid will react and release CO2 add solution to separating funnel slowly open tap whilst holding separating funnel upside down remove aqueous sodium carbonate layer wash organic layer and run into a flask What are the results of using phenolphthalein Alkali turns pink Acid turns colourless What are the results of using methyl orange? Alkali turns yellow Acid turns orange End point turns orange Draw reflux apparatus. Include: - Liebig condenser. - COLD water in (bottom right). - COLD water out (top left) - Pear-shaped flask. - Anti-bumping granules. - Open top. - HEAT. Draw the gas collection apparatus? Draw the titration equipment (1) Draw the titration equipment (2) Draw the gas syringe equipment Draw the distillation equipment (1) Draw the distillation equipment (2) Draw the filtration equipment