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Edexcel Chemistry: C2 - 14th June 2017 Unofficial Markscheme

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) 31.8g
b) C - 97.5 (1 Mark)
c) C - 1; +1 (1 Mark)
d) Cu2S

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 (2 Marks)
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
Why potassium chloride has a high melting point: Because there are strong electrostatic force of attaction so lots of energy is needed to break those bonds
Explain why argon is used in filament bulbs instead of air: Argon is inert (unreactive) so it prevents the hot filament to react with O2 and get burnt out

(edited 6 years ago)

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Reply 1

ChezPlayz

mass of magesium question 31.8 pretty sure

Reply 2

lighth_lawliet

Original post by ChezPlayz

mass of magesium question 31.8 pretty sure

Yes but which question was it?

Reply 3

ChezPlayz

Original post by NateRiver

Yes but which question was it?

Cant remember sorry

Reply 4

Zainyg

Original post by NateRiver

Any answers will be added in :smile:

1)
a) Breaking bonds; energy taken in
b) Exothermic; products energy less than reactants
c)

2)
3)
4)

5)
Six Marker) Isotopes; Neon-22 has 12 neutrons; Relative Atomic Mass calculation

6)
Six Marker) 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

Multiple Choice Questions: Sulfur; (s); Galium
Empirical Formula : Cu2S
Maximum Mass of Magnesium Oxide: 31.8g

Galium?!?

Reply 5

Mermaidqueen

There was a balancing equations question about putting potassium into water, so lets find the balanced equation. It was: 2K+2H20--> 2KOH+H2

(edited 6 years ago)

Reply 6

ChezPlayz

Original post by Zainyg

Galium?!?

I got gallium but dont know.

Reply 7

Akshar99

1 c) State two ways two was to increase the rate of reaction
1) Add catalyst. 2) use magnisium powder rather than ribbon

1 d) Explain why increasing concentration of the acid increases the rate of reaction?
-> there are more particals in the same volume/area.
-> so the frequency of the successful collision increases