Tests for Organic and Inorganic Ions

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  • Created by: lolza_98
  • Created on: 08-05-16 20:14

Idoform Test

Testing for a CH3CH(OH)

A few cm3 of the liquid then add sodium hydroxide solution and idodine solution and warm

Yellow percipitate= CH3CH(OH)

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Acidified Potassium Dichromate

Testing for a primary/secondary alcohol as opposed to tertiary alcohol 

Mix a few cm3 of the liquid or solution with acidified potassium dichromate solution in a test tube and warm in water bath 

Orange solution turns green= primary or secondary alcohol

Stays orange= not a primary or secondary

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Phosphorous Pentachloride

Testing for an OH group 

Add a few cm3 of the liquid and then add a few crystals of PCl5 

Test any gas released with a glass rod dipped in concentrated ammonia solution

Gas released, misty fumes, solid disappears, heat released, white smoke= alcohol/OH group present; white smoke ammonia chloride 

No gas released, no white smoke= no alcohol/OH group present 

 

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Silver Nitrate Solution

Testing for the presence of halogen atoms in a halogenalkane 

Add one cm3 of halogenalkane to few cm3 of ethanol; add silver nitrate solution and warm in a water bath

White percipitate= chloroalkane 

Cream perciptate= bromoalkane

Yellow percipitate= iodoalkane 

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Sodium Carbonate or Sodium Hydrogen Carbonate

Test for a COOH group 

To a few cm3 of the liquid/solution add half a spatula measure of solid sodium carbonate or sodium hydrogen carbonate 

Gas released, solid disappears, bubble through limewater goes cloudy= COOH group present 

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Magnesium

Testing for carboxlyic acid

Add a few cm3 of a liquid and then add a strip of magnesium 

Gas released, magnesium disappears, test gas with lit split- pop sound = carboxlyic acid 

No gas = no carboxlyic acid 

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Appearance of Non-organic ions

Observe colour and state; say whether cystalline or solid 

White crystaline solid= doesn`t contain transition metal/ not a metal compound, possibly compound of group 1,2 or ammonia compound 

Blue= possibly contains copper ions, copper compound 

Pale green= possibly contain 2+ iron ion/ iron compound 

red-brown= possibly contains 3+ iron ion/ iron compound 

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Solubility in Water

Add a few spatula measures of solid to a test tube of deionised water 

Dissolves to form a colourless solution= soluble in water, compound of group 1, 2, aluminium, zinc or ammonium

Dissolves to form a colourless solution= soluble in water, blue solution is copper, pale green is iron 2+, yellow/orange is iron 3+ 

Does not dissolve = insoluble in water 

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Sodium Hydroxide

Testing for Metal Cat ions 

Dissolve a spatula measure of the sample in deionised water and add a few drops of NaOH solution. Then add about 5cm3 of NaOH 

Pale green percipitate does not dissolve in excess NaOH = Iron 2+ present 

Brown percipitate does not dissolve in excess NaOH = Iron 3+

White perciptate that does not dissolve in excess NaOH = Magnesium 2+ 

White percipitate dissolves in excess NaOH to form colourless solution= Aluminium 3+ or Zinc 2+ 

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Magnesium Nitrate

Distinugishing between carbonate and hydrogencarbonate 

Dissolve a spatula measure of the sample in deionised water and add a few cm3 of magnesium nitrate solution. If no percipitate immediately forms boil the contents. 

White percipiate appears immediately = carbonate ions 

Colourless solution, white percipitate, appears on boiling = hydrogencarbonate

No percipiate = no carbonate ions 

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Dilute Nitric Acid

Testing for carbonate ions and hydrogencarbonate 

Place a few cm3 of dilute nitric acid in a test tube and add a spatula measure of the sample 

Effervescence, solid disappears, gas evolved can be passed through limewater in other test tube = carbonate or hydrogencarbonate 

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Barium Chloride

Testing for Sulfate Ion 

Dissolve a spatula measure of the sample in a dilute nitric acid and add a few cm3 of barium chloride soultion 

white percipitate = sulfate ions 

No percipitate = no sulfate ions 

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Potassium Chromate

Testing for Barium ions 

Dissolve a spatula measure of the sample in deionised water and adda few cm3 of potassium chromate 

Yellow percipitate that redissolves in dilute hydrocholric acid to form solution = Barium 2+ 

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Potassium Thiocynate

Testing for Iron 3+ 

Dissolve a spatula measure of the sample in deionised water and add a few cm3 of potassium thiocynate 

Blood red = iron 3+ 

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Silver Nitrate Solution

Testing for halide ions 

dissolve a spatula measure of the spatula in dilute nitric acid and add a few cm3 of silver nitrate solution. Add dilute ammonia solution. Add concentrated ammonia solution 

White percipitate dissolves in dilute ammonia = chloride ion 

Cream percipitate that does not dissolve in dilute ammonia but in concentrate ammonia = bromide ions 

Yellow percipitate, does not dissolve in either = iodine ion  

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Concentrated Sulfuric Acid

Testing for halide ions 

place a spatula measure of solid sample in a test tube and add a few drops of concentrated sulphuric acid 

misty fumes when rod dipped in concentrated ammonia solution = chlordie ions, HCl fumes 

misty fumes, red- brown vapour = bromide ions 

misty fumes, purple vapour, rotten egg smell, yellow solid = idodide ions 

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Combustion

Place a few drops of the liquid on a watch glass and ignite with lit split 

clean blue flame = low carbon content, possibly alcohol

sooty orange flame = high  carbon content/ possibly alkane/ alkene 

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Appearance and smell of organic ions

colourless liquid with characteristic spirit/ alcohol smell = alcohol 

fruit/ sweet smell = ester 

colourless with sharp smell = carboxlyic acid/ ethanoic acid 

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Miscibility or solubility in water

Testing for polarity of the liquid 

Add a few cm3 of the liquid to deionised water in a test tube

Mixes with water one layer formed = polar, possilbly alcohol/ carboxlyic acid 

Two layer formed = Non- polar 

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Flame Test

Dip nichrome wire on concentrate HCl; touch sample with the wire, then hold out in a blue flame 

Crimson = lithium 

Yellow/ orange = sodium 

Lilac = Potassium 

Brick red = calcium 

Green = Barium 

Blue- green = copper 

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