Edexcel iGCSE Chemistry Paper 2C 15 June, sorry should have specified in the question... Please send the answers and the question numbers you remember Please also point out any mistakes or mistakes in question numbers
1a) Glass rod / stirrer and Bunsen Burner 1b) Liquids that dissolve is solvent 1c) Colourless liquid is solution 1d) Solid insoluble impurities removed in stage 2 (filtration), salt crystals removed in stage 3 (crystallisation) 1d) Crystallisation point is when crystals begin to form 1e) Water evaporates from the heat
2a) Water levels rose as oxygen in air reduced as it reacted with iron to produce hydrated iron oxide, stopped as all oxygen had been used up 2b) Cant remember what it asked but it was: iron? + sulphuric acid? -> iron sulphate + hydrogen 2c) 2HNO3 + CuO -> Cu(NO3)2 + H2O 2d) Warmed acid as it increased rate of reaction 2e)In excess when solid starts to form at the bottom (stops dissolving)
3a) Metal oxide is alkaline (e.g. sodium hydroxide) and non metal oxides are acidic (e.g. sulphur dioxide) The question asked for the element that would form oxides, so any metal (sodium, magnesium etc.) is correct for the first one, and any non metal apart from argon is correct for the second one. you did not have to specify the oxide, i.e. magnesium oxide, sulphur dioxide etc. 3b) Dot cross diagram of MgCl with each with a full outer shell, and chloride ions with one donated electron, charges where Mg2+ and Cl- x2 3c) Ionic bonding is transfer of electrons, producing a positive and negative ion(s), with electro-static forces of attraction between oppositely charged ions 3d) Why ionic is strong: strong electro-static forces between oppositely charged ions which need a lot of energy to break
4a) Titration 4b) Pipette to add 25cm3 4c) Methyl orange is yellow before, orange OR red when neutral 4d) Fe2+ gives green precipitate, Fe3+ gives brown(/orange) precipitate 4e) Burrette readings, can't remember exact values but values had to be given to 2 decimal places 4f) 22.60, 22.45, 22.55 for the concordant results in boxes 2, 3, 4 with an average of 22.533....., 22.53 to have 2dp, like the given results
5a) Isomer has the same chemical formula but different structural formula 5b) Isomer of with 4 carbons and 8 hydrogens with a double bond 5c) Test with bromine water, which goes colourless in the one with a double bond (but-1-ene i think?) and stays orange in the other one 5d) CH3-CH2-CH2-OH 5e) Cant remember the monomer but ( )n with the double bond broken and carbon bonds outside brackets
6a) Refinery gas has lowest boiling point, bitumen was most viscous 6b) Long chain hydrocarbon -> C10H20 and x number of ethene I'm not sure about this one, this answer may not be correct, lots of people have put different things 6c) Cracking is important as shorter chain hydrocarbons are in higher demand, as they are used for cars (i.e. gasolene etc..) 6d) Long Hydrocarbon + Oxygen --> Carbon, Carbon Monoxide, Carbon Dioxide and Water i think it is C8H18 + 6O2 > 6C + CO2 + CO + 9H2O, variants without Carbon may be accepted
7a) 2.75g 7b) Using 0.0625 moles from A, 1500cm3 of Carbon Dioxide
cant remember question number but:
3:1 ratio electrons:Al so 20/3 moles of Al mass= moles x mr so 6.666 x 27 = 180g
Hope this mark scheme helped!!! Good luck in Triple Physics and the rest of your exams!
How does he know when the crystallisation point is reached? i wrote take a sample and let it cool in air and if it crystallises then the point has been reached.
How does he know when the crystallisation point is reached? i wrote take a sample and let it cool in air and if it crystallises then the point has been reached.
And for the aluminium mass i got 180g.
yea same, do you remember what question number that was?