Group 4
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Deduct an experiment to compare the thermal stability of two different group 2 nitrates
Put same amount of nitrate in a test tube Heat both using a Bunsen burner Use a gas syringe and measure rate of production of gas
Explain the origin of flame test colours
Heat is transferred from heating when Bunsen burner is turned on Electrons promoted to higher energy levels Electrons return to lower energy levels Light is emitted and released
Explain the trend of electron affinities down group 7
Electron affinity becomes less negative/exothermic Atomic radius increases Less electrostatic attraction between nucleus and outer electron Increased shielding from inner electrons Increased shielding outweighs effect of nuclear charge
What does group 2 metal add water form
Metal hydroxide and H2
What colour are group 2 oxides
They are white solids
What is formed when metal oxide is added to water
Metal hydroxide
Explain the solubility of group 2 hydroxides and sulfated down the group
Group 2 sulfates decrease in solubility down the group Group 2 hydroxides increase in solubility down the group
Explain the 2 ways to Test for Nitrate ions
1)Measure how long it takes for a specific amount of oxygen to be produced. Use a gas syringe or amount needed to relight a growing splint 2) measure how long it takes for a specific amount of NO2 to be produced NO2 is a brown gas so easily observed but must be done in a fume cupboard as it is toxic
Test for carbonate ions
Measure length of time it takes for a specific amount of CO2 to be produced CO2 turns limewater cloudy
Colours of halogens
Fluorine is yellow Chlorine is pale green Bromine is brown orange Iodine is grey solid
Write a general equation when a halogen reacts with COLD ALKALIS in a disproportionation reaction
X2 + 2NaOH —> NaOX + NaX + H2O
What’s the general equation when a halogen reacts with HOT Alkalis in a disproportionation reaction
3X2 + 6NaOH —> NaOX3 + 5NaX + 3H2O
How is bleach(NaClO) made and what are the products
Made via Sodium hydroxide(2 moles) plus Cl2 Products: H2O,bleach and NaCl Chlorine is oxidised and reduced
Explain the trend of reducing agents down group 7
Reducing power increases down the group Talk about atomic radius shielding proton number etc
Test for Halide ions
Add HNO3 and Silver Nitrate solution to a solution of the ion. I- are yellow(insoluble in concentrated NH3) Cl- are white (precipitate dissolves in dilute NH3) Br- are cream(dissolves in concentrated NH3)
Magnesium plus steam forms..
MgO not Mg(OH)2
Group 2 Metal oxide plus water forms
Metal hydroxide
H2SO4 + NaX → X is a halogen specifically Cl,Br,I
NaHSO4 + HX X is a halogen specifically Cl,Br,I
Test for Carbonates
HCl reacts with Carbonates and hydrogencarbonates to make CO2 gas Bubble through limewater Positive result is a cloudy colour
Test for sulfates
Add HCl to the compound to remove any Carbonates Add barium chloride White precipitate produced
Test for ammonium compounds(Litmus paper test)
• Add NaOH to compound, gently heat using Bunsen burner • If Ammonium compound is present, ammonia gas produced Use damp red litmus paper, Ammonia will dissolve and turn blue
Ionic equation between ammonium compound and hydroxide
NH4+ + OH- → NH3 + H2O
Test for ammonium hydroxide Will this test guarantee that the compound is ammonium hydroxide
Same as test for ammonium compound Red litmus paper will turn blue as hydroxides are alkaline Since litmus paper turns blue for any alkaline further tests are needed to confirm you have an alkali
Explain why the reaction between metal oxides and silicon dioxide is necessary
Neutralisation reaction Metal oxides are corrosive Salt silicates that are inert form