Chemistry A-Level Techniques and Procedures

1. ____ the balance

2. place a ____ ____ on the balance

3. accurately record the mass of the ____ plus the weighing bottle

4. empty the solid into the ____ and accurately reweigh the empty weighing bottle

5. ____ mass of empty weighing bottle from mass of solid + weighing bottle

1. rinse pipette with ____ ____ and then a small volume of the solution to be pipetted

2. using a ____ ____ draw enough liquid into the pipette until it is exactly the right volume

you will know it's the right volume when the ____ __ __ ____ is level with the mark

3. ____ the outside of the pipette

4. run the liquid from the pipette to the ____

5. touch the tip of the pipette to the ____ of the glassware

1. rinse burette with ____ ____ and then a small volume of the solution to be used

2. close the ____ ____

3. pour the solution into the burette using a ____. fill to above the zero line

4. use a ____ to hold your burette in place

5. open the tap and allow the solution to run into a beaker until there are no ____ ____

6. record the start reading to the nearest ____ cm^3

7. carry out the titration and record the end reading to the nearest ____ cm^3

8. find the ____ by subtracting the initial reading from the final reading

1. use an ____ ____ to collect the gas over water

the system must be ____ ____

2. the ____ ____ delivers gas to the burette

3. the burette is inverted in a ____ ____ and itself filled with water initially

4. the ____ will enter the burette and you can take a reading

1. put the reactants in a ____ ____ flask

2. add ____ ____ ____ (stop large bubbles forming suddenly and allow for a smooth boiling process)

3. vertically attach a ____ so the water flows in at the bottom and out at the top

4. heat with a ____ ____ so the reaction mixture boils gently

5. vapours should reach no more than ____ up the column before condensing back into a liquid

1. mix the organic product with another ____ liquid such as water

2. allow the layers to separate and dispose of the aqueous layer using a ____ ____

3. if acid impurities are present, add ____ ____ ____ solution and shake well to remove them

4. if the crude product is alkaline and needs neutralising, add a ____ ____ until it's neutral

5. dry the crude product by adding ____ ____ ____ and swirling

6. the pure product can then be separated by ____

1. carry out an ____ ____ ____ to find how much acid solution is needed to neutralise 25cm^3 alkaline solution

2. transfer 25cm^3 alkaline solution to a clean ____ ____

3. use a ____ to add the correct amount of acid to neutralise the alkali

4. transfer the neutralised solution to a clean ____ ____

5. heat over a Bunsen burner to evaporate the water until ____ start to appear

6. filter the mixture and wash the residue with cold ____ ____

7. transfer the residue to a ____ ____ and heat in an oven to dry the solid

8. the oven's temperature should be below the melting point of the ____

9. at regular intervals, remove the watch glass and solid, cool in a ____ and weigh

10. heat until the solid has dried to a ____ ____

11. leave to cool in a ____ (these allow materials to cool in a dry atmosphere so prevent reabsorption of moisture)

1. in a beaker, warm ____ insoluble base in dilute acid

2. warm until the solution is ____, adding more solid base if needed

3. leave to ____

4. filter off excess solid base and transfer the ____ to a clean, dry evaporating basin

5. follow the procedure for ____ (given above)

1. add in equal volumes of the desired salt solutions in a beaker to form a ____ of the insoluble salt

2. filter and wash the precipitate several times with cold, ____ ____

3. transfer the precipitate to a clean watch glass and place in a ____ ____

ensure the oven's temperature is ____ the melting point of the salt

4. heat to constant mass and then leave to cool in a ____

1. put the mixture in a pear-shaped flask and add ____ ____ ____

2. the thermometer should read the temperature of the ____

3. when the vapour temperature is about ____ degrees below the boiling point of the liquid, put the collecting beaker in place

4. collect the liquid until the temperature of the vapour rises ____ the boiling point of the liquid you are collecting

you can repeat this for multiple ____ in a mixture if necessary

1. spot the test mixture and ____ ____ on a pencil baseline 1cm from the base of the TLC plate

2. suspend the plate in a baker containing the ____

3. cover with a watch glass to prevent ____

4. remove the plate when the solvent is near the top and mark the ____ ____ with a pencil

5. allow the plate to ____

6. locate spots. you may need to add a stain or view under ____ ____

____ is used to detect colourless organic compounds

____ is used to detect compounds with free amino groups such as proteins, amino acids, and amines

the TLC plate fluoresces under ____ ____. compounds with aromatic rings or conjugated structures appear as dark spots

5. match the calculated ____ values with those in a database

1. select a solvent in which the desired substance is very soluble at high ____ and insoluble at low ____

2. dissolve the mixture in the ____ quantity of hot solvent

3. filter to remove any ____ ____ and retain the filtrate

for this step, use a ____ ____ to retain heat

4. leave the filtrate to cool until crystals form and collect the crystals by ____ ____

5. rinse the crystals with ____ ____

6. dry the crystals in a ____ ____

1. connect a conical flask to a vacuum pump via the ____ ____

2. dampen a piece of filter paper and place flat in the ____ ____

3. switch the ____ ____ on then pour in the mixture to be filtered

4. this creates a partial ____ so the filtrate is quickly pulled through

5. disconnect the flask from the vacuum pump before turning the pump off to prevent ____ ____

1. seal the end of a glass ____ ____ by heating it to melting in a Bunsen flame

2. tap the ____ end of the tube into a solid so a small amount goes into the tube

3. tap the tube so the solid falls to the bottom of the ____ end

4. fix the tube in melting point apparatus and gently heat the surrounding liquid, ____ to ensure even heating

5. note the temperature at which the solid starts and finishes melting - the difference is the ____ ____

6. compare the ____ value to the published value

the wider the melting range, the more ____ the substance

a pure substance melts within ____K of the true melting point

1. calculate the mass of solute required and weigh out in a ____ ____

2. pour 100cm^3 ____ ____ into a 250cm^3 beaker

3. transfer the weighed ____ into the water

4. ____ the weighing bottle to calculate actual mass in the beaker

5. stir the mixture with a ____ ____ to ensure the solute has completely dissolved

6. transfer the solution to a clean 250cm^3 ____ ____

7. rinse the beaker and stirring rod with deionised water, ensuring all ____ go into the flask

8. add deionised water, swirling at intervals to mix the contents, until the level is within about ____ cm^3 of the mark on the flask's neck

9. use a dropping pipette to add deionised water so the ____ __ __ ____ is level with the mark on the neck of the flask at eye level

10. insert a stopper in the flask and ____ it several times to ensure thorough mixing

1. rinse a clean dry beaker with the ____ ____ then half-fill it

2. use a pipette filler to pipette 25cm^3 of the stock solution into a 250cm^3 ____ ____

3. make up to the mark with the usual procedure. you will have diluted your solution by a factor of ____ here

1. rinse and fill the burette with ____

2. pipette 25cm^3 alkaline solution into a ____ ____

3. add 2-3 drops of ____ and swirl to mix

____ is colourless in acidic solutions and pink in basic ones

4. run the acid, ____ the flask, until the solution just changes colour

5. the first titration is the ____ titration to indicate roughly how much acid is required

6. titrate again. run the acid solution to 1cm^3 below the rough titre then add acid ____

swirl after each drop until the colour of the ____ just changes

7. repeat until you have three ____ results within 0.10cm^3 of each other and use the mean

____ ions are strong enough oxidising agents to oxidise iodide ions to iodine

therefore, we can use iodine-thiosulfate titration to find the ____ of a solution of chlorate (I)

1. pour some chlorate (I) solution into a clean, dry beaker and transfer a 25cm^3 ____ into a conical flask

2. add excess iodide ions, using a measuring cylinder to transfer e.g. 15cm^3 of 0.5 mol dm^3 potassium ____ to the conical flask

3. add excess hydrogen ions by adding 20cm^3 of 1 mol dm^3 ____ ____

at this stage, the contents will be ____ due to iodine being produced

4. fill burette with a standard solution of 0.1mol dm^3 ____ ____

5. put the conical flask on a ____ ____ to make the end point easier to see

6. carry out titrations. near the end point, the contents of the flask will be a ____ ____ colour

at this point, add a few drops of ____ solution

the contents of the flask will turn ____ ____ due to iodine being present

7. the end point is where the solution is ____

1. select the filter with the ____ colour to the test solution

this allows for the greatest values of ____

2. make up a range of ____ ____ of the test solution, both above and below the concentration of the unknown solution

3. zero the colorimeter using a ____ of pure solvent

4. measure the ____ of each of the standard solutions

5. plot a ____ ____ of concentration against absorbance

6. measure the absorbance of the ____ sample and use the calibration curve to determine its concentration

1. pour a known volume of water into a copper ____ and record its temperature

2. weigh a ____ ____

keep the cap on to reduce fuel loss by ____

3. support the calorimeter over a spirit burner containing the ____ to be tested

4. surround with a ____ ____ to help reduce energy losses

5. remove the cap of the spirit burner and light the ____

6. carry on heating until the temperature has risen by about ____ to ____ K

7. ____ the spirit burner and replace the cap

8. keep stirring the water. make a note of the ____ temperature reached

9. weigh the burner again. you can use this to determine ____ ____ __ ____

1. use a measuring cylinder to add a known volume of a known concentration of acid to an ____ ____

2. use a thermometer to take the initial ____

3. use a ____ ____ to add a known volume of a known concentration of alkali and stir to mix

4. top the vessel with a ____ with a hole in and place the thermometer through the hole in the ____

5. record changes in ____ every 30 seconds until there is no further change

6. calculate the maximum temperature reached and use this to determine ____ ____ __ ____

1. add a known volume of a known concentration of reactant solution to an ____ ____

2. add a known mass of solid reactant in ____

3. top the vessel with a ____ with a hole in

4. record changes in temperature every 30 seconds until there is no ____ ____

5. plot a graph of temperature against time and ____ to find the theoretical maximum temperature change

1. pass an electric current through the ____

you may need to collect ____ products

if so, do this by filling test tubes with water as these will ____ the water

if electrolysis to be carried out to ____ a metal:

the ____ will need to be made of the impure metal

the electrolyte must contain ____ of that metal

the ____ should be made of the pure metal

1. set up apparatus, place several test tubes of water in the ____ ____

2. strongly heat the ____

this ensures that when the hydrocarbon vapour passes over it, the temperature is high enough for any ____ reactions to take place

3. heat the ____ gently, collecting any gases that pass into the collection tubes

4. change and cork any full tubes to prevent ____ ____ and continue to heat

5. discard the first tube of gas because this will just be ____ air

6. continue heating until no more ____ is produced

7. remove the ____ ____ from the collection trough before stopping heating to prevent suck back

8. leave to ____, then dismantle

9. test any liquid product with ____ ____. it should remain orange/brown

10. test the gas by shaking with bromine water. it should ____

add a few drops of ____ ____

if an alkene is present, the bromine water will change from orange/brown to ____

similar to a ____ in that a light source is passed through a sample and absorbance or transmission is measured

in the case of a colorimeter, the coloured light used as a source can only be selected from a specific number of different ____

a visible spectrophotomer can give data for absorption or transmission for any given value of the ____ ____

1. construct the ____ ____ whose electrode potential is to be measured

for a metal ion/metal half cell, the ____ will be made from the solid metal

if the reaction involves two ions of the same element in different oxidation states, the electron should be ____

in that case, the solution will contain a ____ of the two ions

in all cases, ensure ____ ____

2. connect the half-cell to a ____ ____ ____ ____

3. connect the two electrodes to a ____ ____ ____

ensure the reading on the voltmeter is ____

this ensures that the half-cell connected to the ____ ____ of the voltmeter is the positive electrode

if the reading is ____ switch the connections on the voltmeter

4. take the voltmeter reading to find ____ ____ (or standard ____ ____ in this case

you need to ___ the pH electrode for temperature because pH is dependent on temperature

1. wash the electrode with ____ ____

2. transfer into a ____ ____ of pH 7.00

3. check the bulb of the electrode is completely immersed, then wait for the reading to ____

ensure the ____ reads 7.00 and adjust to that value if necessary

calibrate to pH ___ for acidic solutions

calibrate to pH ___ for alkaline solutions

to measure both acidic and alkaline solutions with a wide range of values, calibrate with acidic, alkaline and neutral ____

first, prepare a ____ ____ in deionised water

1. warm deionised water in a small conical flask and add the salt, ____ frequntly

2. keep adding ____ until no more dissolves

3. leave the mixture to cool to ____ ____

4. filter and discard the ____

Ksp is ____ dependent, so take the ____ of the solutions you're working with

the second stage is determining ____ of one of the ions in solution

just one is sufficient because the concentration of one ion is ____ to the other

for a basic solution, concentration can be determined using acid-base titration with the ____ ions

for a coloured solution, it can be determined by ____

1. allow a mixture to reach ____

2. determine ____ of one of the components in the equilibrium mixture

3. use this to work out the other concentrations and calculate ____ using the equation

a measure of the closeness of agreement between an individual test result and the accepted reference value

the closeness of agreement between independent measurements made under the same conditions

the difference between an individual measurement and the true value or accepted reference value of the quantity being measured

an estimate attached to a measurement which characterises the range of values within which the true value is asserted to lie

the opposite of uncertainty (if uncertainty is great, the measurement is unreliable)

uncertainty is usually taken to be ____ a division on either side of the smallest scale on the scale you're using

percentage uncertainty = uncertainty x number of measurements x 100 divided by ____ ____

when you use a ____ measuring device, you should record all the figures shown on the instrument

when using a non-digital device, you should record all the figures that are certain plus one that is ____