PPQ CHEM

• How to balance complete combustion equation for alcohols?


  Same number of CO2 as Carbon in alcohol

  Number of H20 is half number of hydrogens in alcohol
• What is a primary , secondary and tertiary alcohol?

  Primary - 1 R group

  Secondary - 2 R group

  Tertiary - 3 R group
• What is the conditions for primary to carboxylic acid [2O]?

  K2Cr2O7 , H2S04 , Heat under reflux
• What happens when secondary alcohol is oxidised?

  Ketone + H20 is formed , Dichromate / K2Cr2O7 , heat under reflux , H2S04, acid catalyst
• What is the reagent for HaloAlkane to Ethanol?

  NaOH / Sodium Hydroxide
• What is the trend of the C - HALOALKANE bond when going down the group?

  Strength of it decreases due to less electronegative elements down the group thus faster hydrolysis
• How to convert alcohol into alkene?


  Add H2S04 and Heat
• How to go from secondary alcohol to ketone?

  Reflux
• Outline the apparatus and method when going from alcohol to haloalkane?

  Apparatus:

  Pear - Shaped Flask

  Heat Source

  Condenser

  Method:

  Use seperating funnel to seperate organic and aqueous later, collect organic aqueous layer (density greater)

  Dry With Anhydrous salt (MgSO4)

  Collect fraction distillating at 102 degrees
• What is the colour chamge when going from primary alcohol to aldehyde?

  Seen once, orange to blue
• What are the measurement and observations to measure Hydrolysis?

  Time taken for the precipitate to turn blue
• Why does free radical substitution produce a mixture of products?

  Volativity

  Low reactivity
• What is the trend of reactivity of group 17 halogens when going down the group?

  Decreases due to increased atomic radius, more electrons shielding thus harder to gain an electron as nuclear attraction decreases
• What are the advantages and disadvantages of using chlorine?

  Adv. - Kills Bacteria

  Disadv. - Forms Toxic Compounds
• What forms when a halogen reacts with NaOH and what are the conditions?


  Salt + Chromate Solution + Water

  Cold and Solid NaOH
• What colour is formed when Potassium Bromide, Iodide and Chloride are displaced?

  Chlorine -> Green

  Iodine -> Brown

  Bromine -> Yellow
• What organic solvent colour is formed when Iodine, Chlroine and Bromine are displaced?


  Chlorine -> Colourless

  Bromine -> Yellow

  Iodine -> Purple
• How to test for the prescence of carbonates and what is the ionic equation for it?

  Add Dilte HCL in a test tube and if Effervescence/bubbling occurs, it indicates the prescence of carbonate as CO2 is produced

  Ionic Equation: 2H+ H CO3 2- --> CO2 + H20
• How would you test for the presence of sulfates and what is the ionic equation?

  Add Barium Chloride (BaCl2) and if white precipitate forms, sulfate is identified

  Ionic Equation: Ba 2+ + SO4 2- --> BaSO4
• How would you test the prescence of halide ions?

  Add Silver Nitrate (AgNO3) and chlorine is present if white precipate forms, Bromine is present if Cream precipitate forms and Iodine is present if Yellow precipitate forms.

  Ionic Equation: Ag+ + Cl- --> AgCl
• What type of ammonia solution will the halide dissolve in?

  Chlorine - Dilute

  Bromine - Concentrated

  Iodine - none
• How to test the presence of ammonium and what is the ionic equation?

  Heat with NaOH but not ammonia

  Place it through Indicator and if it turns blue, ammonia present

  Ionic Equation: NH4+ + OH- --> NH3 + H20
• Write Ionic equation for displacement of bromine between chlorine?

  2br- + Cl2 --> 2Cl- + Br2
• What is the defenition of first Ionisation Energy?

  Energy required to remove 1 mol of gas from 1 mol of gaseous atoms
• Why does the boiling point increase accros a period form elements with metalic bonds?

  More electrons across the group thus more electrons become delocalised thus more metalic bonds form between cations and delocalised electrons resulting in stronger metalic bonds which require more energy to overcome
• Why can magneisum bromide conduct elec. in aqueous state but not in a solid state?


  In aqueous: Ions are mobile and free to move around the structure and carry charge

  In Solid: Ions are fixed in position in a lattice
• How does LDF exist in Br2?

  Between Molecules
• Why does MgBr have a high melting point?

  It is a giant ionic structure containing strong ionic bonds between oppositely charged ions which require a lot of energy to overcome
• Why does the first ionisation energy decrease when going from berillium to boron?

  As for berillium, the 2s orbital is completely filled whereas boron has one electron in a 2p orbital as well, and the 2s orbital is shielded much more than the 2p orbital.
• Why does the first ionisation energy decrease going from nitrogen to oxygen?

  oxygen has an orbital where it has a pair of electrons which repel eachother thus it is easier to lose an electron
• What happens to the atomic radius across a period?

  N. of protons across a group increase and electron shielding stays constant thus nuclear attraction increases thus atomic radius decreases
• Why is silicon described as a p block element?


  As their outer electron is in the p-subshell
• Why does P4 have a higher melting point than Cl2?

  As P4 has stronger LDF because of more electrons thus more energy required to break LDF
• Describe the bonding in Magnesium and Silicon?


  Magnesium contains strong metalic bonds between positive ions and contains delocalised electrons

  Silicon contains covalent bonds between atoms
• Why does first Ionisation energy decrease down th group?

  As down the group, there is increased electron shielding which outweighs increased nucleae thus atomic radius increases and nuclear attraction decreases
• What is Group 2(Mg) reaction with water?

  Mg + H2O --> 2MgO + H2
• What is group 2(Mg) reaction with Oxygeb?

  2Mg + O2 --> 2MgO
• Mg + H2s04 ?


  MgSo4 +H2
• Reacttion between group 2 oxides (MgO) and water?

  MgO + H20 -> Mg(OH)2
• What type of structure are metals?

  Giant Lattices