Edexcel Chemistry: C2 - 14th June 2017 Unofficial Markscheme

Why sodium has high melting point?
Because there are strong electrostatic force of attaction so lots of energy is needed to break those bonds

2 a) MCQ which substance gives out coloureds it was D sodium

Which salt is insoluble salt.
I think so it was lead sulfate not sure

Balanced equation of potassium in water.
2k + 2H2O --> 2K(OH) + H2

Why caesium is more reactive then lithium
Because it has more shells so the electrostatic force of attraction between negative electron and positive nucleus is weaker so it could be lost easily

4 marker about electronic configuration of oxygen and calcium.
--> calcium is a cation, it has 2 electrons in it outer shell so it losses those 2 electrons and becomes 2+ ion. Now it's electronic configuration is 2.8.8
Oxygen is a non metal it gains 2 electrons from ca and becomes 2- ion. It's electronic configuration is 2.8

Explain why argon is used in filament bulbs instead of air.
Argon is inert (very unreative) so it prevents the hot filament to react with O2 and get burnt out

wtf i just don't understand 12 people out of 24 thought it was 21.8 and the other 12 thought it was 31.8 , most are certain it was 21.8

2a) What was the question because the coloured cation was a different question.

Any answers will be added in 1) a) Breaking bonds; energy taken in (2 Marks) b) Exothermic; products energy less than reactants; difference in height is energy released (3 Marks) c) Add catalyst; increase magnesium surface area, higher temperature of solution (2 Marks) d) More particles in the same volume/Particles are closer together; frequency of the collision increases 2) a) D - Sodium b) C - Lead Sulfate c) 2K + 2H2O → 2KOH + H2 d) Caesium has more electron shells; force of attraction between negative electron and positive nucleus is weaker; so it could be lost easily e) Calcium is a cation; it has 2 electrons in its outer shell; it losses those 2 electrons and becomes 2+ ion; now it's electronic configuration is 2.8.8; oxygen gains 2 electrons from Calium and becomes 2- ion; its electronic configuration is 2.8 (4 Marks) 3) a) C - Al2(SO4)3 b) Hydrochloric Acid; Barium Chloride Solution c) C - (s) 4) a) b) 97.5 c) 1; +1 d) Cu2S e) 31.8g 5) Six Marker) Isotopes; Neon-22 has 12 neutrons; Relative Atomic Mass calculation (6 Marks) 6) a) Metallic bonds; creates a sea of delocalised electrons; electrons free to move; conducts electricity b) Dot and Cross Diagram: http://www.bbc.co.uk/staticarchive/f81332272e2264487b8e7d37212575efb8bfbef7.gif (2 Marks) c) Period 3; Group 5; Phosphorous (4 Marks) d) Giant Covalent Molecular Structures; Diamond is very hard; Each carbon atom forms four covalent bonds; Graphite is structured in layers; layers can slide over each other; graphite contains free electrons; conducts electricity (6 Marks) Multiple Choice Questions: Sulfur; Chromium; ... + 2KBr → ... + Br2

wtf i just don't understand 12 people out of 24 thought it was 21.8 and the other 12 thought it was 31.8 , most are certain it was 21.8

The question about what to add to test for chloride ions was dilute nitric acid and silver nitrate solution

The question about what to add to test for chloride ions was dilute nitric acid and silver nitrate solution

No it said test for sulphate ions. Its Barium chloride and HCl

grade boundaries anyone? I made silly mistakes probably dropped 15 marks like i crossed out the 2 in front of the k.

I think on the mark scheme they'd put barium chloride (solution)
They don't tend to go into much detail

Sulpahte ion test
-HCL
- Barium chloride (solution)
I swear if u have to put solution to get the mark i'd be p*ssed

so I'm right? because I wrote Chromium. that's why I questioned Galium because I'm not sure about that one