I have a chemistry exam for tomorrow and I'm stressing. I don't know what to revise 😣😣😫
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Chemisty C2 - 2015 UNOFFICIAL Markscheme watch
- 14-12-2015 17:51
- 15-12-2015 17:49
So this is chemistry (C2) right?
- 16-12-2015 19:04
is this for aqa c2 higher? many thannks x
- 17-01-2016 15:33
what was the answer to the 6 marker
- 17-01-2016 16:44
Thank you so much for this. Do you have any progress on that 6 marker or know what the question was?
- 27-01-2016 18:05
this helped me so so much as it was my mock paper and i have to resit it. thank you!!
(Original post by neil20143)
Hi I tried to make an unofficial mark scheme for this. Please be free to add things
1a. State one conclusion about the effect of temperature on the rate of reaction? (1 mark)
-An increase in temperature increases the rate of reaction
aii. One reason why? (1 mark)
-Because the volume of gas being produced at 40 degrees was more rapid than at 20 degrees.
a(iii). Average rate (1 mark)
-2 cm cubed per second (I think)
1 (b) two students should the student keep constant? (2 marks)
-Mass of Marble Chips
-Concentration of acid
b ii. Increasing the surface area affect the rate of reaction? (2 marks)
-Increases the rate of reaction
-As the particles are colliding more frequently (more successful collisions)
c. Why does a catalyst reduce costs?
-Because less energy is needed to start the reaction (as it has a lower activation energy)
(there may be alternatives)
2 (a). What could the student see? (1 mark)
-Copper being formed (brown) or zinc disappearing
2(b).Improves the investigation? (2 marks)
Improvement: Use a lid/ insulate the container
Reason: Prevents heat from being transferred to the surroundings/escaping.
2c (6 marker - will do later at some point)
3 (a). How does a metal conduct electricity? (4 marks)
-Delocalised electrons can move through the metal
-Transfer electrical charge
-Sea of moving electrons (structure)
-Lattice of positive ions (structure)
3(b). Describe the structure of an alloy is different to a metal (2 marks)
-Different elements with different sizes
-Distort layers in the mixture, preventing them from sliding over each other.
-Irregular pattern of atoms.
3(c). Why is Nitinol used in braces? (1 mark)
3(c) (ii). Why are coins not made out of pure copper? (1 mark)
-Because it is too soft so will corrode
3 (c) (iii)). Aluminium Oxide
3 (c) (iv). How can the reaction produce two different products? (1 mark)
-Made using different reaction conditions / any specified reaction condition (e.g. pressure, temperature).
-Using different catalysts
3(d). Instrumental methods are used to detect impurities? (2 marks)
Any two from:
-They use very little samples.
4 (a). Why does Lithium have 7 as it's atomic number? (3 marks)
-3 + 4 = 7 which is its mass
-electrons have a very small mass.
4(b). Complete the sentences (2 marks)
4(c). Isotope differences (3 marks)
-18-Oxygen had 2 more neutrons than 16-Oxygen
-Same number of protons
-Same number of electrons
5 (a). Name a soluble compound that contains silver
5(a) ii Compound containing carbonate ions (1 mark)
-Potassium or Sodium Carbonate
5(b) (1 mark)
5(c) (i). State how lead nitrate can be obtained from lead nitrate oxide (1 mark)
-Evaporate and leave to dry.
5c(ii) (1 mark)
Pbo + 2HNO3 = PB(NO3) + H2O
5c (iii). number of atoms in the compound
5(d). Empirical Formula (4 marks)
6(a). Structure and bonding in sodium chloride (4 marks)
-Sodium atoms lose one electron to form positive ions
-Chloride ions gain one electron to form negative ions
-Giant ionic structure
Any of these should get the mark I think
6(b). Other products when brine is electrolysed (2 marks)
6(c). Ethical reason for not putting Iodine in food (1 mark)
-People may not want to have these extra Iodine amount (no choice)
6(d) (i). (2 marks)
-3 electrons lone pairs and one covalent bond
6(d) (ii). Why does Iodine have a low melting point (3 marks)
-Weak intermollecular forces
-Little energy needed to break them down
6(d) (iii). Why does iodine not conduct electricity? (2 marks)
-No overall charge so can't carry electrical charge
(I'm not sure about this question)
- 29-02-2016 16:59
Has anyone got a mark scheme?
- 08-03-2016 21:25
can someone send what the 6 mark question is please?
- Political Ambassador
- 08-03-2016 21:34
- 17-03-2016 22:23
is this for the foundation or higher paper?
- 18-03-2016 18:14
Thank me later
- 30-03-2016 20:33
Anyone got the c3 H 2015 MS?
- 10-04-2016 21:19
is this an aqa paper?