Unit 6

Question 1

method for the measurement of the molar volume of a gas

Answer 1

1. Set up the apparatus to capture and measure gas evolved from a reaction in the boiling tube
2. Place 30cm3 of 1 moldm-3 ethanoic acid in the boiling tube
3. Place approximately 0.05g of calcium carbonate in a test tube. Weigh the test tube and its contents accurately
4. Remove the bung from the boiling tube and tip the calcium carbonate into the boiling tube. Quickly place bung in the boiling tube
5. Once the reaction is over, measure the volume of gas produced
6. Reweigh the test tube that contained calcium carbonate.
   7.Repeat 6 more times, increasing the mass of calcium carbonate by about 0.05g each time. Do not exceed 0.40g of calcium carbonate

Question 2

Equipment for the measurement of the molar volume of a gas

Answer 2

-boiling tube
-stand and clamp
-bung fitted with delivery tube to fit boiling tube
-water bath for gas collection
-100 cm3 measuring cylinder
- 50 cm3 measuring cylinder
-test tube
-mass balance
-1 moldm-3 ethanoic acid
-powdered calcium carbonate

Question 3

safety procedures for the measurement of the molar volume of a gas

Answer 3

-wear eye protection
-remove the bung if the delivery tube gets blocked, clear the blockage and repeat the procedure from the start
- avoid skin contact with the ethanoic acid, especially if the skin is broken or sensitive

Question 4

method for determination of the enthalpy change of a reaction using Hess’s Law

Answer 4

1. Place an approximately 3g of solid potassium carbonate in a test tube. Accurately weigh the test tube and its contents
2. Use a burette to dispense 30cm3 of 2 moldm-3 hydrochloric acid into a polysterene cup, which is supported in a beaker
3. Measure the temperature of the acid
4. Gradually add potasium carbonate to the acid, stirring all the time and monitoring the temperature of the acid
5. Reweigh the empty test tube
   6.Repeat 1-5 using 3.5g of potassium hydrogencarbonate instead. Record the lowest temperature reached.

Question 5

equipment for determination of the enthalpy change of a reaction using Hess’s Law

Answer 5

-two test tubes
-2 moldm-3 dilute hydrochloric acid
-solid potassium carbonate
-solid potassium hydrogen carbonate
-thermometer able to read up to 50ºC
-polysterene cup
-250cm3 or 400cm3 beaker
-burette, clamp, stand
-stirring rod
-mass balance
-spatula

Question 6

safety procedures for determination of the enthalpy change of a reaction using Hess’s Law

Answer 6

-wear eye protection
-avoid skin contact with the reactants and products

Question 7

method for finding the concentration of a solution of hydrochloric acid

Answer 7

1.Wash out the 250cm3 volumetric flask with distilled water
2.Use the pipette to tranfer 25cm3 of the hydrochloric acid solution into the volumetric flask. Use distilled water to make the solution up to the mark.
3. Prepare your apparatus for the titration. The burette should contain the sodium hydroxide solution and the conical flask should contain the dilute hydrochloric acid solution.
4. Pour a 25cm3 aliquot of the diluted hydrochloric acid into the conical flask. Use phenolphthalein as the indicator.
5. Titrate the contents of the flask against the sodium hydroxide solution. Record all burette readings to the nearest 0.05cm3
6. The end point is indicated by the contents becoming pale pink and insisting 5 seconds while swirling.
7. Conduct further titrations unitl you have two concordant titres
8. record results in a table

Question 8

equipment for finding the concentration of a solution of hydrochloric acid

Answer 8

-burette, clamp and stand
-sodium hydroxide solution (0.08dm3 previously standardised)
-bench hydrochloric acid ( 1mol dm-3)
-phenolphthalein
-250cm3 conical flask
-25cm3 volumetric pipette plus safety filler
-100cm3 beakers for transfer of solutions
-funnel for filling burette
-250cm3 beaker
-250cm3 volumetric flask

Question 9

safety procedures for finding the concentration of a solution of hydrochloric acid

Answer 9

-wear eye protection
-avoid skin contact with acid, alkali or indicator
-always use a pipette filler
-take care when clamping and filling the burette that it does not crack or topple over

Question 10

calculation for number of moles in full volume using an aliquot volume

Answer 10

(full volume)(no. of moles in aliquot volume) / aliquot volume in which you know moles = no. of moles in full volume

Question 11

method for preparation of a standard solution from a solid acid and its use to find the concentration of a solution of sodium hydroxide

Answer 11

1.Weigh an empty test tube. Scoop approximately 2.5g of sulfamic acid into the test tube.
2.Accurately reweigh the test tube and its contents
3. Dissolve the sulfamic acid in approximately 100cm3 of water in a beaker
4. Transfer the solution, including the washings, to a 250cm3 volumetric flask and use distilled water to make up the solution to the mark.
5. Prepare your apparatus for the titration. The burette will contain the acid and the conical flask will contain the sodium hydroxide solution
6.Pour a 25cm3 aliquot of sodium hydroxide solution of unknown concentration into the 250cm3 conical flask
7. Use of methyl orange as the indicator
8.Titrate the contents of the flask against sulfamic acid solution prepared. Conduct further titrations until you have two concordant titres

Question 12

equipment for preparation of a standard solution from a solid acid and its use to find the concentration of a solution of sodium hydroxide

Answer 12

-burette, clamp and stand
-solid sulfamic acid
-sodium hydroxide solution of unknown concentration
-methyl orange indicator
-250cm3 conical flask
-25cm3 volumetric pipette plus safety filler
-100cm3 beaker for transfer of solutions
-funnel for filling burette
-250cm3 beaker
-250cm3 volumetric flask
-mass balance

Question 13

safety procedures for preparation of a standard solution from a solid acid and its use to find the concentration of a solution of sodium hydroxide

Answer 13

-wear eye protection.
-avoid skin contact with acid or alkali
-take care when clamping and filling the burette that it does not crack or topple over

Question 14

method for the investigation of the rates of hydrolysis of some halogenoalkanes

Answer 14

1.Set up a water bath by filling the 250cm3 beaker up to the three-quarters mark with water at around 50ºC
2. Take three test tubes and add 5 cm3 of ethanol to each one
3. Add four drops of 1-iodobutane to the first tube, four drops of 1-bromobutane to the second tube and four drops of 1-chlorobutane to third tube. Label the tubes.
4. Loosely place a bung in each test tube and place the test tubes in the water bath
5. Take three clean test tubes and pour 5cm3 of silver nitrate solution into each one. Then place the test tubes in the water bath.
6. When the halogenoalkane-ethanol solutions have reached the temperature of the water bath, add one test tube of silver nitrate solution to one of the halogenoalkane-ethanol solutions and replace the bungs. At the same time, start the stop clock.
7. Measure the time taken for a precipitate to appear. As soon as the solution becomes cloudy, stop the clock.
8. Repeat steps 6 and 7 for each halogenoalkane, repeat 1-7 again for 1-bromobutane, 2-bromobutane and 2-bromo-2-methylpropane instead of halogenoalkanes.

Question 15

equipment for the investigation of the rates of hydrolysis of some halogenoalkanes

Answer 15

-250cm3 beaker
-12 test tubes with bungs
-1-chlorobutane
-1-bromobutane
-1-iodobutane
-2-bromobutane
-2-bromo-2-methylpropane
-0.05moldm-3 silver nitrate solution
-15cm3 of ethanol
-dropping pipettes
-two 10 cm3 measuring cylinders
-stop clock
-labels for test tubes
-kettle

Question 16

safety procedures for the investigation of the rates of hydrolysis of some halogenoalkanes

Answer 16

-wear eye protection
-avoid skin contact with the reactants
-no naked flames as ethanol and halogenoalkanes are highly flammable
-well ventilated laboratory to prevent inhalation of fumes

Question 17

method for making propanal (7a)

Answer 17

1. Wear protective gloves when handling acidified potassium dichromate solution. Carefully add 20cm3 of acidified potassium dichromate solution to a 50cm3 pear-shaped flask. Cool the flask in ice-water bath.
2. Set the flask up for distillation, keeping it in the ice-water
   3.Place a few bumping granules into the pear-shaped flask
3. Measure 1.5cm3 of propan-1-ol into a measuring cylinder and add 5cm3 of distilled water to this
4. Using a pipette, add the propan-1-ol solution, a few drops at a time, into the pear-shaped flask
5. When all propan-1-ol has been added, remove ice-water bath and allow the flask to warm to room temp.
6. Light a bunsen burner under the flask and heat very gently with a small flame
7. Collect 3-4 cm3 of clear, colourless liquid in a test tube which is immersed in cold water in a beaker.

Question 18

method for testing for propanal (7b), silver mirror test

Answer 18

1. Prepare a sample of Tollen’s reagent by adding 5 drops of sodium hydroxide solution to 2 cm3 of silver nitrate solution in a test tube
   2.Add just enough ammonia solution to this test tube so that the brown ppt dissolves completely. Using water bath, gently warm this test tube
2. Add 10 drops of the distillate (created after making propanal). If propanal has been produced, a silver mirror will appear

Question 19

method for testing for propanal (7b), magnesium ribbon

Answer 19

1. Add a small piece (1cm) of magnesium ribbon to the distillate .
2. Observe if a reaction happens, Propanal should not react with magnesium

Question 20

method for testing for propanal (7b), sodium hydrogencarbonate

Answer 20

1. Add spatula of sodium hydrogencarbonate to the distillate in a test tube
2. Propanal should not produce any effervescence

Question 21

method for testing for propanal (7b), Fehling’s solution

Answer 21

1. Add 1cm3 Fehling’s solution to 1cm3 of the distillate in a test tube
2. Place test tube into a beaker of hot water. A colour change to reddish brown indicates propanal is present

Question 22

equipment for making and testing for propanal. making andtesting for propanoic acid

Answer 22

-simple distillation apparatus
-acidified potassium dichromate (VI)
-propan-1-ol
-distilled water
-teat pipette
-Bunsen burner
-stand and clamp
-measuring cylinders
-anti-bumping granules
-test tubes
-spatula
-thermometer
-10cm3 beakers
-0.05 moldm-3 silver nitrate solution
-2 moldm-3 dilute ammonia solution
-2 moldm-3 sodium hydroxide solution
-small pieces of magnesium ribbon
-sodium hydrogencarbonate
-Fehling’s solution

Question 23

safety procedures for making and testing for propanal

Answer 23

-wear goggles and chemical-resistant gloves
-propan-1-ol and propanal are flammable
-avoid skin contact with the reactants and products

Question 24

method for making propanoic acid

Answer 24

1. Using gloves, add 20cm3 of acidified potassium dichromate solution to a 50cm3 pear-shaped flask. Cool the flask in an ice-water flask
2. Set the flask up for reflux, keeping it in the ice-water bath
3. Place a few anti-bumping granules into the pear-shaped flask
4. measure out 1.5cm3 of propan-1-ol into a measuring cylinder and add 5cm3 of distilled water to this
5. Using a pipette, add the propan-1-ol solution, a few drops at a time, down the reflux condenser. This must be done slowly.
6. When all the propan-1-ol has been added, remove from ice-water bath and let to warm to room temp
7. Light a Bunsen under the flask and heat gently under reflux with a small flame for 30 minutes
8. Distil your product using distillation apparatus. Collect 3-4cm3 of clear, colourless liquid in a test tube which is immersed in cold water in a beaker

Question 25

method for testing for propanoic acid, silver mirror

Answer 25

1. Prepare a sample of Tollen's reagent by adding 5cm3 of sodium hydroxide solution to 2cm3 of silver nitrate solution in a test tube 2. Add ammonia until all brown ppt dissolves. Using water bath, gently warm this test tube 3. Add 10 drops of distillate, no reaction should occur

Question 26

method for testing for propanoic acid, magnesium ribbon

Answer 26

1. Add a small piece (1cm) of magnesium ribbon to the distillate . 2. Observe if a reaction happens, Propanoic acid should react with magnesium so effervescence seen

Question 27

method for testing for propanoic acid, sodium hydrogencarbonate

Answer 27

1. Add spatula of sodium hydrogencarbonate to the distillate in a test tube 2. Propanoic acid produces effervescence.

Question 28

method for testing for propanoic acid, Fehling's solution

Answer 28

1. Add 1cm3 Fehling's solution to 1cm3 of the distillate in a test tube 2. Place test tube into a beaker of hot water. Propanoic acid does not cause a colour change.

Question 29

method for following the rate of the iodine-propanone reaction by a titrimetric method

Answer 29

1. Mix 25cm3 of 1 moldm-3 aqueous propanone with 25 cm3 of 1 moldm-3 sulfuric acid in a beaker 2. Start the stop clock the moment you add 50cm3 of 0.02moldm-3 iodine solution. Shake the beaker to mix well 3. Using a pipette, withdraw a 10cm3 sample of the mixture and transfer it to a conical flask 4. Stop the reaction by adding a spatula measure of sodium hydrogencarbonate, note exact time at which this is added 5. Titrate the remaining iodine present in the sample with 0.01moldm-3 sodium thiosulfate (VI) solution, using starch indicator. Record your results. 6. Repeat 3-5 at time intervals of 3 minutes.

Question 30

equipment for following the rate of the iodine-propanone reaction by a titrimetric method

Answer 30

-50cm3 of 1.0 moldm-3 aqueous propanone solution -50cm3 of 1.0moldm-3 sulfuric acid -50cm3 of 0.02moldm-3 iodine solution -0.01moldm-3 sodium thiosulfate(VI) solution -20cm3 of 1% starch solution -sodium hydrogencarbonate -100cm3 beaker -conical flasks -10cm3 graduated pipette plus safety filler -spatula -stop clock

Question 31

safety procedures for following the rate of the iodine-propanone reaction by a titrimetric method

Answer 31

-dispose of the product down a fume cupboard sink with running water -perform a risk assessment before practical is carried out -wear eye protection -ensure room is well-ventilated -avoid skin contact with the reactants and products -do not run this practical for more than 12 minutes in total

Question 32

method for investigating a 'clock reaction' (Harcourt-Esson, iodine clock)

Answer 32

1. Measure 10cm3 of potassium iodide solution into a small beaker standing on a white tile 2. Add 5cm3 of sodium thiosulfate solution to the potassium iodide solution 3. Add 10 drops of starch solution to the mixture in the small beaker. 4.Measure 10cm3 of the sodium peroxodisulfate solution. Pour into the mixture prepared and start the stop clock. 5. Stop the clock when a blue colour appears in the beaker, note time taken. 6.Repeats steps 1-5 with different volumes of potassium iodine solutions (from 10cm3 to 2 cm2) with constant volumes of peroxodisulfate solutions and vice versa. When decreasing the volume of one of the solutions, water is added so that the total volume always is 25cm3.

Question 33

equipment for investigating a 'clock reaction' (Harcourt-Esson, iodine clock)

Answer 33

-100cm3 of 0.2 moldm-3 sodium peroxodisulfate solution -100cm3 of 0.2 moldm-3 potassium iodide solution -50cm3 of 0.05moldm-3 sodium thiosulfate solution -20cm3 of 1 % starch solution -distilled water - white tile - four 10cm3 measuring cylinders -dropping pipettes - nine 100cm3 beakers -stop clock

Question 34

safety procedures for investigating a 'clock reaction' (Harcourt-Esson, iodine clock)

Answer 34

-wear eye protection -avoid skin contact with the reactants and products

Question 35

method for finding the activation energy of a reaction

Answer 35

1. pipette 10cm3 of phenol solution and 10cm3 of bromide solution into one boiling tube 2. Add four drops of methyl red indicator to the mixture 3. Pipette 5cm3 of sulfuric acid solution into another boiling tube 4. Use a kettle and a beaker to prepare a water bath with a temperature of 75ºC. Stand the two boiling tubes in the water bath 5. When the contents of the boiling tubes have reached the temperature of the water bath, mix the contents of the two tubes by pouring rapidly from one tube into the other and then pouring the mixture back into the empty test tube. Start the stop clock at the same time. 6. Leave the boiling tube in the water bath and time until the colour of the methyl red indicator disappears 7. record results and repeat experiment with: 65ºC, 55ºC, 45ºC, 35ºC, 25ºC and 15ºC. when plotting graph change ºC to K and calculate 1/T

Question 36

equipment for finding the activation energy of a reaction

Answer 36

-70cm3 of 0.01moldm-3 aqueous phenol solution -70cm3 bromide solution -50cm3 of 0.5 moldm-3 sulfuric acid -methyl red indicator -three 100cm3 beakers -four boiling tubes -10cm3 pipette -thermometer (0-110ºC) -stop clock -two 500cm3 beakers -kettle

Question 37

safety procedures for finding the activation energy of a reaction

Answer 37

-wear eye protection and suitable chemical-resistant gloves -avoid skin contact with the reactants and products -Do not inhale any fumes that may be produced

Question 38

method for finding the Ka value for a weak acid

Answer 38

1. Set up the datalogger to read the pH, or calibrate the pH meter 2. Pipette 25cm3 of 0.1 moldm-3 ethanoic acid solution into a 250cm3 conical flask 3. Fill a burette with sodium hydroxide solution 4. Add two or three drops of phenolphthalein to the conical flask 5. Titrate the ethanoic acid solution with sodium hydroxide solution until the mixture just turns pink. Swirl the mixture to ensure the end point has been reached. 6. Pipette a further 25cm3 of 0.1 moldm-3 ethanoic acid solution into the 250cm3 conical flask 7. Record the pH of this solution

Question 39

equipment for finding the Ka value for a weak acid

Answer 39

-100cm3 of 0.1 moldm-3 ethanoic acid solution -100cm3 of 0.1 moldm-3 sodium hydroxide solution -datalogger and pH probe or pH meter -stand, clamp and boss for pH probe -50cm3 burette -burette stand 250cm3

Question 39

equipment for finding the Ka value for a weak acid

Answer 39

-100cm3 of 0.1 moldm-3 ethanoic acid solution -100cm3 of 0.1 moldm-3 sodium hydroxide solution -datalogger and pH probe or pH meter -stand, clamp and boss for pH probe -50cm3 burette -burette stand -250cm3 conical flask -25cm3 pipette and filler -phenolphthalein indicator

Question 40

safety procedures for finding the Ka value for a weak acid

Answer 40

-wear eye protection -avoid skin contact with the reactants and products -take care when clamping and filling the burette that it does not crack or topple over

Question 41

method for investigating some electrochemical cells

Answer 41

1. use sandpaper to clean strips of zinc and copper 2. Set up a zinc half-cell by pouring 50cm3 of zinc sulfate solution into the 100cm3 beaker and standing the strip of zinc in the beaker 3. Set up a copper half-cell by pouring 50cm3 of copper(II) sulfate solution into a separate 100cm3 beaker and standing the strip of copper in the beaker 4. Make an electrical connection between the two beakers by joining them with a strip of filter paper that has been dipped in a saturated solution of potassium nitrate 5.Use the connecting wires and crocodile clips to join the two metal strips with a voltmeter 6. Record the electrode potential of the Zn(s)IZn (aq) and Cu (aq) I Cu (s) system to give a positive value. 7. Repeat with following combinations: Zn and Fe (II), Fe (II) and Cu, Zn and Ag and Cu and Ag

Question 42

equipment for investigating some electrochemical cells

Answer 42

-50cm3 of 0.4 moldm-3 zinc sulfate solution -50cm3 of 0.4moldm-3 copper (II) sulfate solution -50cm3 of 1.0moldm-3 iron(II) sulfate solution -50cm3 of 0.1moldm-3 silver nitrate solution -saturated potassium nitrate solution -distilled water -one strip of each of the following: zinc; copper; iron; silver -sandpaper -four 100cm3 beakers -strips of silter paper 12cm long -100cm3 measuring cylinder -voltmeter (20V) -connecting wires and crocodile clips

Question 43

safety procedures for investigating some electrochemical cells

Answer 43

-wear eye protection -avoid skin contact with the solutions, run cold running water immeadiately.

Question 44

method for redox titrations with iron (II) ions and potassium manganate

Answer 44

1. Crush the iron tablets using the pestle and the mortar 2.Transfer the crushed tablets to a weighing boat and measure the combined mass of the tablets and weighing boat. Record this mass. 3. Empty the crushed tablets into the small beaker and reweigh the weighing boat. Record this mass. 4. Add most of the 100cm3 of 1.5moldm-3 sulfuric acid to the small beaker. Stir to dissolve as much of the tablets as possible 5.Filter the solution into the volumetric flask. Rinse the beaker with the rest of the sulfuric acid and filter the washings into the volumetric flask. Add distilled water to make up the solution to the mark. Stopper and shake 6.Pipette 25cm3 of this colution into the conical flask 7. Titrate the iron (II) solution with potassium manganate(VII) solution until it just turns pink. 8.Record results and repeat the titrations until you achieve concordant results

Question 45

safety procedures for redox titrations with iron (II) ions and potassium manganate

Answer 45

-wear eye protection -avoid skin contact with the reactants and products -take care when clamping and filling the burette that it does not crack or topple over

Question 46

equipment for redox titrations with iron (II) ions and potassium manganate

Answer 46

-five iron tablets -100cm3 of 1.5 moldm-3 sulfuric acid -100cm3 of 0.005moldm-3 potassium manganate (VII) -distilled water -pestle and mortar -100cm3 beaker -25cm3 measuring cylinder -two 250cm3 beakers -250cm3 volumetric flask and stopper -spatula and glass rod -filter funnel and filter paper -50cm3 burette and burette stand -25cm3 pipette and pipette filler -250cm3 conical flask -white tile -mass balance

Question 47

method for redox titrations with sodium thiosulfate and iodine

Answer 47

1.Wash the pipette, burette and conical flask with distilled water. Pipette then rinsed with potassium iodate (V) solution and burette with sodium thiosulfate before the titration 2. Using a pipette and filler, place 25cm3 of potassium iodate solution into a conical flask. To this add 20 cm3 of dilute sulfuric acid and 10cm3 of potassium iodide solution 3. Fill the burette with sodium thiosulfate solution using a funnel 4. Place the conical flask on the white tile and titrate the prepared mixture against sodium thiosulfate. Yellow solution will turn colourless at end point. Keep adding sodium thiosulfate until a pale yellow colour is achieved, at this point add 5 drops of starch, making a blue-black mixture. 5. Continue the titration, end point achieved by a colour change from blue-black to colourless. 6. Write down results of titre and repeat until concordant results are achieved

Question 48

safety procedures for redox titrations with sodium thiosulfate and iodine

Answer 48

-wear eye protection -avoid skin contact with the reactants and products -take care when clamping and filling the burette that it does not crack or topple over

Question 49

equipment for redox titrations with sodium thiosulfate and iodine

Answer 49

-potassium iodate (V) solution -0.05 moldm-3 potassium iodide solution -1 moldm-3 sulfuric acid -0.1 moldm-3 sodium thiosulfate solution -distilled water -pipette and filler -burette -filter funnel -white tile -conical flask -starch solution in dropping bottle -clamp and stand

Question 50

method for the preparation of a transition metal complex

Answer 50

1. Weigh between 1.5g of copper (II) sulfate, record mass. (weigh empty test tube, add copper sulfate, reweigh) 2.Add 4cm3 of water to test tube using a graduated pipette 3.Prepare a water bath by pouring hot water from a kettle into a 100cm3 beaker. Stand the test tube in the water bath and stir until copper sulfate dissolves 4.Pipette 6cm3 of ethanol into a beaker 5. Remove the test tube from water bath 6. Stirring all the time, add 2cm3 of concentrated ammonia solution to the copper sulfate in a fume hood using gloves 7.Pour contents of test tube into the beaker with ethanol, mix well and cool in ice bath 8.Using Buchner funnel and flask, filter the crystals. Wash test tube with cold ethanol and add washings to Buchner funnel, then rinse crystals with cold ethanol 9. scrape crystals from filter paper to new piece of filter paper. Cover with second piece of filter paper, pat to dry crystals 10.Measure and record their mass

Question 51

safety procedures for the preparation of a transition metal complex

Answer 51

-wear eye protection -Ammonia soilution should only be used in fume cupboard while wearing chemical resistant gloves -water bath not heated with Bunsen due to ethanol being flammable

Question 52

equipment for the preparation of a transition metal complex

Answer 52

-copper(II) sulfate pentahydrate -10cm3 ethanol -2cm3 concentrated ammonia solution -crushed ice -Buchner flask and funnel and vacuum filtration apparatus -filter paper -one test tube -one 50cm3 beaker -one 100cm3 beaker -one 10cm3 graduated pipette -one pipette filler -one spatula -one stirring rod -mass balance -access to a kettle

Question 53

method for the preparation of aspirin

Answer 53

1. weigh 2g of 2-hydroxybenzoic acid and put it in a pear-shaped flask. Clamp the flask and suspend it in a beaker of water 2.Add 5cm3 of ethanoic anhydride to the 2-hydroxybenzoic acid. Add five drops of concentrated sulfuric acid to the mixture in the flask. Fix a condenser on the flask. 3.In a well-ventilated room, use a Bunsen to heat mixture in water bath, swirl until all solid has dissolved 4. Continue warming the mixture for another 10 minutes 5. Remove the flask from the hot water bath. Add 10cm3 of crushed ice and some distilled water to the reaction mixture to break down any unreacted ethanoic anhydride 6. Stand the flask in a beaker of iced water until precipitation appears to be complete 7.Filter off the product using Buchner funnel and suction apparatus 8.Wash the crystals with the minimum volume of iced water 9.Recrystallise the aspirin in minimum volume of mixture of ethanol and water 10. Filter and dry the crystals 11. Measure mass and melting point of crystals

Question 54

safety procedures for the preparation of aspirin

Answer 54

-wear eye protection -if the room is not well ventilated, use fume cupboard -ethanol is flammable -avoid skin contact with the reactants and products

Question 55

equipment for the preparation of aspirin

Answer 55

-10cm3 ethanoic anhydride -2g 2-hydroxybenzoic acid -1cm3 concentrated sulfuric acid -distilled water -ethanol -two 10cm3 measuring cylinders -condenser -small pear-shaped flask -stand, clamp and boss -two 250cm3 beakers -dropping pipette ice -Bunsen burner, tripod, gauze and safety mat -mass balance -Buchner funnel, Buchner flask, suction pump and filter paper to fit funnel -melting point apparatus