Required Practicles

• Separating different dyes in inks - PAPER CHROMATOGRAPHY

  1) draw pencil line near bottom of filter paper

  2) add spot of ink to line

  3) place sheet into beaker of solvent (water)

  4) put lid onto beaker

  5) solvent seeps up the paper, carrying ink with it (dyes will move at different rates)

  6) when solvent has nearly reached top of paper, take out and leave to dry

  
• Separating insoluble solids from liquids - FILTRATION

  1) set up equipment as shown

  2) fold filter paper into cone shape and place in filter

  3) pour mixture into filter and leave to drip into beaker

  
• Separating soluble solids from solutions - EVAPORATION


  1) set up equipment as shown

  2) pour solution into evaporating dish

  3) slowly heat solution - solvent will evaporate + solution will become more concentrated

  4) keep heating until all you have left are dry crystals

  
• Separating soluble solids from solutions - CRYSTALLISATION


  1) set up equipment as shown

  2) pour solution into evaporating dish and gently heat

  3) once some solvent has evaporated/ crystals start to form, remove from heat

  4) crystals should start to form in cold, concentrated solution

  5) filter crystals out of solution

  6) leave in warm place to dry

  
• Filtration and distillation to separate rock salt:

  Rock salt - a mixture of salt and sand

  
  

  1) set up equipment as shown

  2) grind mixture to ensure salt crystals are small

  3) put mixture in water and stir

  4) filter the mixture through filter paper - sand grains won't fit through, but salt will

  5) evaporate water from salt to form dry crystals

  
• Separating out solutions - SIMPLE DISTILLATION

  1) set up equipment as shown

  2) heat solution

  3) vapour is cooled, condensed and collected

  4) rest of solution is left behind in flask

  
• Test for unsaturated hydrocarbons - HALOGENATION

  
• Separating mixtures of liquids - FRACTIONAL DISTILLATION


  1) set up equipment as shown

  2) put mixture in flask and place fractioning column on top

  3) heat

  
  

  4) the different liquids will have different boiling points - will evaporate at different temperatures

  5) when the first liquid has collected, raise the temp until the next reaches the top

  
• Finding out concentrations - TITRATION


  1) set up equipment as shown

  2) using a pipette and pipette filler, add a set volume of alkali to a conical flask

  3) add two or three drops of indicator too

  4) use funnel to fill burette with acid of known solution - record initial volume of acid

  5) using burette, add acid to alkali a bit at a time

  6) give the conical flask a regular swirl + slow down nearer the colour change

  7) indicator changes colour when all alkali has been neutralised

  8) record final volume of acid in the burette + use it along with initial reading to calculate volume needed to neutralise the alkali

  
• Making soluble salts using an insoluble base


  1) set up equipment as shown

  2) pick the right acid and insoluble base - e.g. insoluble metal oxide, hydroxide or carbonate

  3) gently warm dilute acid using Bunsen burner, then turn off

  4) add insoluble base to acid a bit at a time, until no more reacts

  (When excess sinks to the bottom of the flask)

  5) filter out excess solid to get salt solution

  6) gently heat solution using water bath to evaporate some water

  7) then stop heating and allow to cool

  8) crystals of salt should form, which can be filtered out of solution and dried

  
• Extracting metals from their ores - ELECTROLYSIS


  1) set up equipment as shown

  2) connect wires to DC power supply

  3) attach electrodes to wires

  4) turn on power and leave for a bit

  5) positive ions are attracted to negative electrode and negative ions are attracted to positive electrode

  
• Measuring energy transfer


  1) set up equipment as shown

  2) measure energy released by a chemical reaction in solution

  3) take temperature of reagents, mix in polystyrene cup and measure temperature at end

  4) energy lost to surroundings can be reduced by adding cotton wool around polystyrene cup

  
• Testing the effect of acid concentration on energy released in neutralisation reaction:

  1) put 25cm ^ 3 of 0.25 mol/ dm^3 HCL acid and sodium hydroxide into separate beakers

  2) place beakers in water bath at 25 C until they're both at the same temperature

  3) add HCL followed by NaOH to polystyrene cup with lid

  4) take temperature of mixture every 30 secs + record highest temperature

  5) repeat steps 1-4 using 0.5 mol/ dm^3 and then 1 mol/ dm^3 of HCL

  
• Chemical reactions in a cell produce electricity


  An electrochemical cell is a basic system made up of 2 different electrodes in contact with an electrolyte

  
  

  1) set up equipment as shown

  2) the 2 electrodes must be able to conduct electricity - usually metals

  3) the electrolyte is a liquid that contains ions which react with electrodes

  4) the chemical reactions between the electrodes and the electrolyte set up a charge difference between the electrodes

  5) if the electrodes are then connected by a wire - charge is able to flow + electricity is produced

  6) a voltmeter can also be connected to measure the voltage of the cell

  
• Measuring rates of reaction - PRECIPITATION

  1) set up equipment as shown

  2) you can record the visual change in a reaction if the initial solution is transparent + the product is a precipitate which clouds the solution

  3) you can observe a mark through the solution + measure how long it takes to disappear

  -> the faster the disappearance the quicker the reaction

  
• Measuring rates of reaction - COLOUR CHANGE

  1) set up equipment as shown

  2) if reactants are coloured and the products are colourless, you can time how long it takes for the solution to lose/ gain its colour

  3) place reactants into beaker/ conical flask

  4) set time

  5) record time required

  
• Measuring rates of reaction - CHANGE IN MASS

  1) set up equipment as shown

  2) speed of reaction that produces a gas can be measured using a mass balance

  3) place reactants into beaker and place on mass balance

  4) stopwatch

  5) as the gas is released, the mass disappearing is measured on the balance

  6) the quicker the reading drops, the faster the reaction

  7) take measurements at regular intervals to plot a rate of reaction graph

  
• Measuring rates of reaction - VOLUME OF GAS GIVEN OFF

  1) set up equipment as shown

  2) place reactants into conical flask and place bung on top

  3) start stopwatch

  4) use gas syringe to measure volume of gas given off

  5) the more gas given off, the faster the reaction

  
• Two rates experiments - MAGNESIUM + HCL -> H2 GAS

  1) set up equipment as shown

  2) add a set volume of dilute HCL acid to conical flask and carefully place on mass balance

  3) now add Mg ribbon to acid

  4) quickly plug flask with cotton wool

  5) start stopwatch and record mass on the balance (take readings of mass at regular intervals)

  6) plot results in table, calculate mass lost + plot graph of loss of mass

  7) repeat with more concentrated acid solutions

  
• Two rates experiments - SODIUM THIOSULFATE + HCL -> CLOUDY PRECIPITATE


  1) add a set volume of dilute sodium thiosulfate to a conical flask

  2) place flask on piece of paper with black cross drawn on

  3) add some dilute HCL acid and start start the stopwatch

  4) watch black cross disappear and record time required

  5) repeat with different concentrations

  6) the higher the concentration, the quicker the reaction (quicker the cross disappears)

  
• Reversible reactions - HYDRATED -> ANHYDROUS COPPER SULFATE


  1) set up equipment as shown

  2) put some copper sulfate into dish

  3) heat blue hydrated copper (II) sulfate crystals to drive water off + leaves white anhydrous copper (III) sulfate powder

  (ENDOTHERMIC)

  4) then add a few drops of water to the white powder to get blue crystals back

  (EXOTHERMIC)

  
• Paper chromatography - CALCULATING Rf VALUE

  Rf value = distance travelled by substance / distance travelled by solvent front

  
• Tests for common gases - CHLORINE


  1) dampen litmus paper

  2) put unknown gas into test tube

  3) dip litmus paper in test tube

  
  

  CHLORINE BLEACHES DAMP LITMUS PAPER -> TURNS WHITE

  
• Tests for common gases - OXYGEN


  1) create glowing splint (light then gently blow out)

  2) put unknown gas into test tube

  3) put glowing splint into test tube

  
  

  OXYGEN WILL RELIGHT THE GLOWING SPLINT

  
• Tests for common gases - CARBON DIOXIDE


  1) put unknown gas in test tube

  2) collect unknown gas using a pipette

  3) bubble through test tube of limewater

  
  

  CARBON DIOXIDE TURNS LIMEWATER CLOUDY

  
• Tests for common gases - HYDROGEN


  1) put unknown gas in test tube

  2) light a splint using a Bunsen burner

  3) hold lit splint in open end of test tube

  
  

  HYDROGEN WILL MAKE A SQUEAKY POP SOUND

  
• Tests for anions - CARBONATES


  1) put unknown sample in test tube

  2) use dropping pipette to add a few drops dilute acid

  3) then bubble gas through limewater

  
  

  IF CARBONATE IONS ARE PRESENT SOLUTION WILL TURN CLOUDY

  
• Tests for anions - SULFATES


  1) put unknown sample in test tube

  2) use dropping pipette to add a few drops dilute HCL acid

  3) then add a few drops barium chloride solution

  
  

  IF SULFATE IONS ARE PRESENT, A WHITE PRECIPITATE FORMS

  
• Tests for anions - HALIDES


  1) put unknown sample in test tube

  2) add a few drops dilute nitric acid

  3) then add a few drops silver nitrate solution

  
  

  CHLORIDE IONS GIVE A WHITE PRECIPITATE

  BROMIDE IONS GIVE A CREAM PRECIPITATE

  IODIDE IONS GIVE A YELLOW PRECIPITATE

  
• Tests for cations - FLAME TEST

  1) set up equipment as shown

  2) clean wire loop - dip in HCL and then hold in blue flame of Bunsen burner

  3) then dip loop in sample and hold in blue flame of Bunsen burner

  4) observe new colour of the flame

  
• Tests for cations - SODIUM HYDROXIDE TEST


  1) put unknown sample into test tube

  2) add a few drops sodium hydroxide solution

  3) observe for colour change

  
• Corrosion - RUSTING IRON NAILS

  1) set up equipment as shown - three iron nails in three separate boiling tubes

  2) put one in a boiling tube with just water + observe

  3) put another in a boiling tube with air and calcium chloride (to absorb moisture) + observe

  4) put a third in a boiling tube with boiled water and oil + observe