Untitled Flashcards Set

Movement of particles (DIFFUSION)

• Potassium manganate (VII) and water 

 1. Take beaker of water and place som Potassium manganate (VII) at the bottom - the purple colour will slowly spread out to fill the beaker 

• Ammonia and hydrogen chloride 

  • Aqueous Ammonia gives off ammonia gas - HCL gives off hydrogen chloride gas - you'll get a white ring of ammonia chloride forming in the glass tube 

    • Ring does not form in middle but nearest HCL because ammonia particles are smaller and lighter so will move through air quicker 

• Bromine Gas and air

  • Bromine gas is brown which strongly smells. 

  • Fill half a jar full of bromine gas and other half with air - separate with glass plate 

  • When you remove the glass plate youll see the brown bromine gas slowly diffuse through air 

SOLUBILITY EXPERIMENT - ammonium chloride

1. Make saturated solution by adding excess of ammonium chloride to 10cm^2 of water in a boiling tube - you'll know when it's in excess because it starts sinking 

2. Stir the solution and place the boiling tube in a water bath set to 25 degrees

3. After 5 mins check all extra solid has sunk to bottom of tube and use a thermometer to ensure its at 25 degrees

4. Weigh an empty evaporating basin - pour some of solution into basin making sure not to pour any of undissolved solid 

5. Reweigh basin and its contents, then gently heat it with a bunsen burner to remove all the water 

   1. Dont heat to strongly otherwise ammonium will turn into gas 

6. Once all water has evaporated your left with pure ammonium chloride - reweigh its contents 

7. Repeat steps for diff temps 

8. Use equation: 

   1. Solubility = mass of solid/ mass of water removed.
      
      

SEPARATING TECHNIQUE EXPERIMENT 

Filtration: used to separate insoluble solid from liquid

- All you do is pop filter paper into funnel and pour mixture into it - liquid runs through and solid residue is left 

Crystallization: separates solid from solution:

1. Poor solution into evaporating dish and gentry heat - some water will evaporate and solution will get more concentrated

2. Once some water is removed or when you start to see crystals formed remove dish from heat and leave solution to cool

3. Salt should form crystals and become insoluble solid 

4. Filter crystals and leave them in a warm place to dry 

Chromatography:

1. Draw line near bottom of sheet of filter paper - baseline (use pencil so ink won't dissolve)

2. Add spots of different inks to line in regular intervals 

3. Loosely roll this paper and put it in a beaker of solvent (eg water)

4. The solvent depends on what's being tests some dissolve well but sometimes other solvents like ethanol is needed

5. Place lid on container to stop solvent from evaporating 

• How does chromatography separate mixtures: 

  • Different dyes will move up at different speeds/rates 

  • Some will stick to paper and other will dissolve more steadily in solvent and travel more quickly

  • Distance the dyes travel up depends on solvent and paper used

Rf value:

• Ratio between distance travelled by dissolved substance (solute) and distance travelled by solvent 

  • Rf = distance travelled by solute / distance travelled by solvent

• To find distance travelled by solute measure from baseline to centre of spot 

Simple Distillation: 

• Simple is used to separate out solutions - diff liquids 

• Solution is heated and part of the solution that has lowest boiling point evaporates

• The vapour is then cooled, condenses and is collected

• Rest of solution is left in flask 

  • You can use this to separate pure water and sea water- water evaporates and condenses - eventually you'll only be left with salt 

Fractional distillation:

• Used to separate a mixture of liquids

1. Put mixture in flask and you have a fractionating column on top then you heat it 

2. Liquidwill have diff boiling points so they all have diff temps 

3. Liquid with lowest boiling point evaporates first

   1. Temp on thermometer will be boiling point 

Gases in atmosphere: 

• Proportion of oxygen in atmosphere:

  • Iron can determine the percentage of O2 in air 

    • Iron rusts with O2 so iron will remove oxygen

1. Soak some iron wool in acetic catalyst (the acid will catalase experiment) then push the wool into measuring cylinder and invert the cylinder into beaker of water 

2. Record starting position of water using scale on measuring cylinder - will be starting volume of air

3. Over time the water will rise because iron reacts with oxygen to make iron oxide and this freezes up more space for water

4. Leave experiment for about a week or until water stops rising 

5. Record finishing position 

6. USE FORMULA: start volume - final volume/start volume X 100

   1. Should get around 20%

• Phosphorus determines proportion of O2 in air 

1. Place phosphorus in a tube and attach a glass syringe at either end 

2. Make sure one is filled with air and other is empty 

3. Heat the phosphorus and use syringe to pass the air over it 

   1. Will react to crate phosphorus oxide 

4. As reacts amount of oxygen decreases 

5. Measure start/end using scale on syringe 

6. Use formula 

• Burning things with oxygen - flames

  • Magnesium - burns with bright white flame in air and white powder is formed (magnesium oxide) - slightly acidic when its dissolved in water 

  • Hydrogen: burns easily in O2 - explosive - almost invisible flame pale blue flame and only product is water 

  • Sulfur: pale blue flame - produces sulfur dioxide - acidic when dissolved in water 

• Thermal decomposition of metal carbonate - produced CO2

  •  If you heat metal carbonate you get carbon dioxide and metal oxide 

  • This is thermal decomposition which breaks down into simpler substances when heated 

  • Copper II carbonate is a green powder that will easily decompose to form carbon dioxide and copper II oxide 

    • To do experiment heat copper carbonate then collect gas in test tude 

    • Gas collected can be tested to see if its CO2 by doing lime water test 

Reactions of metals 

Titrations 

Making soluble salts

Tests for cations: 

• Flame tests identify metal ions 

1. Clean a platinum wire loop by dipping it into HCI and then holding it in a flame - ones you hold the loop in the flame and it burns without any colour you cna dip it into sample you want to test 

2. Put it back into clear blue part of flame (hottest area)

   1. Lithium - red

   2. Sodium - yellow

   3. Potassium - lilac

   4. Calcium - orange red

   5. Copper - blue green

• Precipitate reactions 

  • Metal hydroxides are insoluble and precipitate out of solution when formed 

  • Add few drops of sodium hydroxide to solution 

• Copper (II) - blue 

• Iron (II) sludgy green 

• Iron (III) reddish brown

ANION tests:

• Produce precipitate:

  • Hydrochloric acid helps detect carbonates:

    • Add dilute HCL to your test sample if carbomates are released then CO2 is produced 

    • Test CO2 with lime water test

  • Sulfates with HCI and Barium chloride:

    • Sulfate ins (SO4 2-) produce white precipitate

      • Add dilute HCL with barium chloride

      • A white precipitate of barium sulfate means the original compound was sulfate 

        • HCI is used to get rid of any traces of carbonate and sulfate before you start)

  • Halide tests: 

    • Used nitric acid and silver nitrate 

      • Add nitric acid followed by silver nitrate solution:

        • Chloride gives white precipitate

        • Bromide gives off cream precipitate 

        • Iodide gives of yellow precipitate

Tests for gases and water

• chlorineL 

  • Bleaches damp blue litmus paper turning it white - may turn red but after it will turn white (is acidic thats why)

• Oxygen 

  • Relights a glowing splint 

• CO2 

  • Turns limewater cloudy

• Hydrogen 

  • Squeaky pop with a lighted splint 

• Ammonia 

  • Turns red damp litmus paper blue - also smells like cat piss 

• WATER

  • Wet copper sulfate is blue and dry copper sulfate is white 

  • You can crystallise it as a test for water 

  • If you heat blu hydrated copper (II) sulfate crystals it drives water off 

  • Leaves white anhydrous copper (II) sulfate powder which doesn't have water bound to it 

• You can test for pure water by testing its freezing and boiling point - freezes at 0 and boils at 100