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edexcel igcse chemistry practicals > practicals i forgot > Flashcards

practicals i forgot Flashcards

1
Q

start by making a saturated solution

How do you investigate how temperature affects solubility?

A
  • make saturated solution by adding excess ammonium chloride to 10cm3 of water in boiling tube
  • stir and place in water bath at 25 degrees
  • after 5 mins check all excess solid has sunk to bottom of tube and use thermometer to ensure temp is 25 degrees
  • weight empty evaporating basin and pour some of solution into basin, making sure to not include undissolved solid
  • reweigh basin and its contents then gently heat using bunsen to remove all water
  • left with pure ammonium chloride which should be reweighed in evaporating basin
  • repeat with water bath at different temperatures
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2
Q

how do you calculate the solubility from the mass of a solvent

A
  • solubility = mass of solid (g) /mass of water removed (g) x 100
  • find mass of solid left in basin
  • find water removed during evaporation
  • solubility
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3
Q

start by drawing a baseline

Explain how to carry out paper chromatography

A
  • draw a line near the bottom of a filter paper sheet in pencil
  • add spots of different inks to line at regular intervals
  • loosely roll up sheet and place in beaker of solvent
  • place a lid on top of the container
  • when solvent has nearly reached the top of the paper take it out and leave it to dry

make sure the level of solvent is below the baseline otherwise inks will dissolve into it

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4
Q

how do you calculate the Rf value of a substance?

A

distance travelled by solute / distance travelled by solvent

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5
Q

start by heating a crucible

how do you find the empirical formula of something using combustion?

A
  • heat a crubile until its red hot (so there is no water or oil)
  • leave to cool then weight the crucible with its lid on
  • add a clean magnesium ribbon to the crucible and reweigh the crucible
  • heat crucible until Mg has turned white and leave lid on to stop solid escaping but leave a small gap to allow oxygen to enter
  • leave to cool and reweigh
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6
Q

start by weighing a bung and test tube

how do you find the empirical formula of something using reduction?

A
  • place a rubber bung into a test tube with a small hole at the end and weigh them
  • take the bung out of the test tube and spread a small amount of copper oxide in the middle of it
  • re-insert bung and weight test tube again
  • clamp test tube and bung above a bunsen burner, and connect to a gas supply
  • expel air from test tube by turning on gas and light it by holding lit splint near hole in end of test tube
  • use bunsen flame to heat until solid changes from black to brownish-pink
  • leave to cool and reweigh
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7
Q

explain how to set up an electrochemical cell

A
  • get two inert electrodes e.g. graphite and cleam them using sandpaper
  • place both electrodes in a beaker filled with your electrolyte
  • connect the electrodes to a power supply using crocodile clips and wires

after cleaning electrodes do not touch them with your hands

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8
Q

start by soaking iron wool in acid

explain how to determine the percentage of oxygen in the air using iron wool

A
  • soak iron wool in acetic acid then push the wool into a measuring cyclinderand invert the cylinder into a beaker of water
  • record starting position of water and leave for a week
  • record finishing position of water

the acetic acid is a catalyst

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9
Q

start by placing phosphorus in a tube

explain how to determine the percentage of oxygen in the air using phosphorus

A
  • place phosphorus in a tube and attatch a glass syringe at either end, making sure one is filled with air and the other is empty
  • heat the phosphorus and use syringes to pass air over it
  • measure the starting and final volumes of air using the scale on one of the syringes
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10
Q

what equation is used to determine the % of oxygen in the air?

A

((start volume - final volume) / start volume) x 100

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11
Q

what is the colour change when copper carbonate thermally decomposes?

A

green to black

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12
Q

three test tubes of acid

explain how to investigate the reaction of metals and acids

A
  • set up three boiling tubes and fill them with equal volumes of dilute hydrochloric acid
  • place pieces of zinc. magnesium and iron in separate test tubes making sure their sizes are equal
  • the speed of reaction is the rate at which bubbles are given off
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13
Q

add alkali to a conical flask

explain how to set up a titration

A
  • using a pipette and pipette filleer, add 25cm3 of alkali to a conical flask with three drops of indicator
  • fill a burette with the acid below eye level
  • ung the burette add acid to alkali a bit at atime, regularly swiriling the flask, slowing down when you are close to the endpoint
  • the indicator changes colour when all the alkali has been neutralised
  • record the volume of acid used
  • repeat until concordant results
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14
Q

spatula of lead nitrate

explain how to make an insoluble salt

A
  • add 1 spatula of lead nitrate to a test tube and add water to dissolve and shake thoroughly
  • do the same with the same amount of magnesium sulfate
  • tip the two solutions into a beaker and stir well
  • filter contents on beaker using a funnel and filter paper
  • swill out beaker with deionised water and tip this into the paper
  • rinse the contents of the filter paper wiht deionised water to ensure all magnesium nitrate is washed away
  • leave to dry in a warm oven
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15
Q

explain how to make a soluble salt

A
  • heat acid in a water bath in a fume cupboard
  • then add some base (copper oxide) to the acid
  • filter off the excess solid to get only the salt and water
  • then use the crystallisation method
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16
Q

explain why you need to use a titration to make a soluble salt

A

the salt is soluble so you cannot use excess of something otherwise it will be impure

17
Q

measure an acid and base into beakers

explain how to measure enthalpy change

A
  • put 25cm3 of HCl and NaOH into separate beakers
  • place the beakers in a water bath set to 25 degrees until they are both at the same temperature
  • add the HCl then the NaOH to a polystryene cup with a lid and thermometer
  • take the temperaure every 30 seconds and record the highesy temp
18
Q

how do you measure caliometry using combustion

A
  • put 50g of water into a copper can and record its temperature
  • weigh a spirit burner and lid
  • put the spirit burner underneath the can and light the wick
  • stir the water constantly until the temperature reaces 50 degrees
  • put out the flame and measure the final temperature of the water
  • weight the spirit burner and lid again

the mass of fuel burnt is the ‘m’ in q=mct

19
Q

explain how to investigate how temperature affects rate of reaction

A

use sodium thiosulfate and hydrochloric acid

20
Q

explain how to investigate how a catalyst affects rate of reaction

A

use hydrogen peroxide, measuring the volume of oxygen gas produced

the catalyst is manganese oxide

21
Q

add acid to a boiling tube

explain how to make and esther

A
  • add concentrated sulfuric acid to a boiling tube using a pipette
  • add 10 drops of ethanoic acid
  • add an equal volume of ethanol
  • place the boiling in a beaker of water and place it onto a tripod
  • heat using a bunsen burner until it boils then turn the bunsen off
  • after 1 minute, remove the tube and allow it to cool
  • once it’s cool, pour the mixture into a test tube of sodium carbonate solution and mix
  • a layer of esther should form on the top

edexcel igcse chemistry practicals (2 decks)

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