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
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
Stir the solution and place the boiling tube in a water bath set to 25 degrees
After 5 mins check all extra solid has sunk to bottom of tube and use a thermometer to ensure its at 25 degrees
Weigh an empty evaporating basin - pour some of solution into basin making sure not to pour any of undissolved solid
Reweigh basin and its contents, then gently heat it with a bunsen burner to remove all the water
Dont heat to strongly otherwise ammonium will turn into gas
Once all water has evaporated your left with pure ammonium chloride - reweigh its contents
Repeat steps for diff temps
Use equation:
Solubility = mass of solid/ mass of water removed.
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:
Poor solution into evaporating dish and gentry heat - some water will evaporate and solution will get more concentrated
Once some water is removed or when you start to see crystals formed remove dish from heat and leave solution to cool
Salt should form crystals and become insoluble solid
Filter crystals and leave them in a warm place to dry
Chromatography:
Draw line near bottom of sheet of filter paper - baseline (use pencil so ink won't dissolve)
Add spots of different inks to line in regular intervals
Loosely roll this paper and put it in a beaker of solvent (eg water)
The solvent depends on what's being tests some dissolve well but sometimes other solvents like ethanol is needed
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
Put mixture in flask and you have a fractionating column on top then you heat it
Liquidwill have diff boiling points so they all have diff temps
Liquid with lowest boiling point evaporates first
Temp on thermometer will be boiling point
Proportion of oxygen in atmosphere:
Iron can determine the percentage of O2 in air
Iron rusts with O2 so iron will remove oxygen
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
Record starting position of water using scale on measuring cylinder - will be starting volume of air
Over time the water will rise because iron reacts with oxygen to make iron oxide and this freezes up more space for water
Leave experiment for about a week or until water stops rising
Record finishing position
USE FORMULA: start volume - final volume/start volume X 100
Should get around 20%
Phosphorus determines proportion of O2 in air
Place phosphorus in a tube and attach a glass syringe at either end
Make sure one is filled with air and other is empty
Heat the phosphorus and use syringe to pass the air over it
Will react to crate phosphorus oxide
As reacts amount of oxygen decreases
Measure start/end using scale on syringe
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
Flame tests identify metal ions
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
Put it back into clear blue part of flame (hottest area)
Lithium - red
Sodium - yellow
Potassium - lilac
Calcium - orange red
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
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
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