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    Do you guys think the grade boundaries will be on the higher side or the lower side?
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    For the 'what could the student observe from this reaction?' question, would I get a mark for saying colour change?
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    (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.
    OR
    -Irregular pattern of atoms.

    3(c). Why is Nitinol used in braces? (1 mark)
    -Hard/strong/corrosive-resistant/smart-alloy

    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.
    -Accurate
    -Sensitive
    -Fast

    4 (a). Why does Lithium have 7 as it's atomic number? (3 marks)
    -3 protons
    -4 neutrons
    -3 + 4 = 7 which is its mass
    -electrons have a very small mass.

    4(b). Complete the sentences (2 marks)
    -Grams
    -Carbon-12

    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
    (1 mark)
    -Silver Nitrate

    5(a) ii Compound containing carbonate ions (1 mark)
    -Potassium or Sodium Carbonate

    5(b) (1 mark)
    -(insoluble)Base

    5(c) (i). State how lead nitrate can be obtained from lead nitrate oxide (1 mark)
    -Crystalisation
    -Evaporate and leave to dry.

    5c(ii) (1 mark)

    Pbo + 2HNO3 = PB(NO3) + H2O

    5c (iii). number of atoms in the compound
    -9

    5(d). Empirical Formula (4 marks)
    Pb2O3


    6(a). Structure and bonding in sodium chloride (4 marks)
    -Ionic Bonding
    -Sodium atoms lose one electron to form positive ions
    -Chloride ions gain one electron to form negative ions
    -Opposites attract
    -Giant ionic structure
    -Cubic Lattice
    -Electrostatic forces

    Any of these should get the mark I think

    6(b). Other products when brine is electrolysed (2 marks)
    -Sodium Hydroxide
    -Hydrogen

    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)
    -Simple molecules
    -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)
    Thank You so much, from this I got approximately 50/60, what did other people get? Thanks again!! (Good Luck for Physics)
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    for 1 a (ii) i said because the steep gradient showed a fast reaction, would i still get the mark?!! help please!
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    (Original post by pineapple4901)
    for 1 a (ii) i said because the steep gradient showed a fast reaction, would i still get the mark?!! help please!
    Did you compare the two and say that the line for 40 degrees was steeper?
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    (Original post by pineapple4901)
    for 1 a(ii) i said because there is a steeper gradient which shows the fast reaction? would i still get a mark? help!!!!!
    maybe, it depends on the examiner really
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    Would I get a mark if for the first question I said increasing the temp increases the rate of reaction TO AN EXTENT
    and my justification was at (x) seconds they both reach the same volume of gas/?????
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    (Original post by neil20143)
    Just checking For what did the student see, is seeing copper being produce the right answer?
    For the bonding in sodium chloride, i mentioned that is an ionic structure, has positive sodium ions (Na+) and negative chloride ions (Cl-). I also mentioned there's electrostatic forces of attraction between the ions so a high mp/bp is needed to break the bonds. But i didnt mention sodium ions lose 1 electron and chlorine atoms gainan electron Will i still be able to get 4 marks?
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    (Original post by TheTruthTeller)
    Would I get a mark if for the first question I said increasing the temp increases the rate of reaction TO AN EXTENT
    and my justification was at (x) seconds they both reach the same volume of gas/?????
    I think they'll tick and ignore the rest to be honest so yes that should be fine
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    (Original post by chemistryboi)
    hi,

    6(d) (iii). Why does iodine not conduct electricity? (2 marks)-No overall charge so can't carry electrical charge

    a better answer would be

    there are no delocalised electrons to carry the current


    3(c) (ii). Why are coins not made out of pure copper? (1 mark)-Because it is too soft so will corrode

    i believe that another reason is

    too high maluability as of structure

    6 mark question?
    i think i made an error in this
    was the reaction endothermic?
    No exothermic gives off heat right!
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    can someone explain carbon 12 to me please i do not see how that's the answer LOL
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    (Original post by chemistryboi)
    hi,

    6(d) (iii). Why does iodine not conduct electricity? (2 marks)-No overall charge so can't carry electrical charge

    a better answer would be

    there are no delocalised electrons to carry the current


    3(c) (ii). Why are coins not made out of pure copper? (1 mark)-Because it is too soft so will corrode

    i believe that another reason is

    too high maluability as of structure

    6 mark question?
    i think i made an error in this
    was the reaction endothermic?
    Exothermic - it gave off heat.
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    (Original post by littleheron)
    For the bonding in sodium chloride, i mentioned that is an ionic structure, has positive sodium ions (Na+) and negative chloride ions (Cl-). I also mentioned there's electrostatic forces of attraction between the ions so a high mp/bp is needed to break the bonds. But i didnt mention sodium ions lose 1 electron and chlorine atoms gainan electron Will i still be able to get 4 marks?
    It depends on the mark scheme They may not even give any marks for the electron transfer and just for the ones you've mentioned (maybe breaking electrostatic forces between the ions point into two seperate marks)
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    (Original post by imyleighx)
    Do you guys think the grade boundaries will be on the higher side or the lower side?
    *Slightly* lower for both C2 and C3.
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    (Original post by JG12333)
    6 (d) iii, I put because there are no free ions to conduct the electricity, pretty confident on that. and for 1 (b) I put the concentration and mass of marble chips. could be wrong though!
    I put concentration too! I don't know if i'm right, although, a higher concentration increases rate of reaction so I would've thought it would be kept the same?
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    (Original post by neil20143)
    *Slightly* lower for both C2 and C3.
    Oh god I hope so! I messed my C3 paper up so badly
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    Hmm according to this I lost 10 marks. Hmm
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    (Original post by DrNippleson)
    can someone explain carbon 12 to me please i do not see how that's the answer LOL
    It is just a fact. All elements are relative to 1/12th of a carbon atom AKA Carbon-12.
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    For improvements for the experiment I wrote use a data logger instead of a thermometer. Do you think that will be right?
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    (Original post by imyleighx)
    Do you guys think the grade boundaries will be on the higher side or the lower side?
    I reckon around 48 for A*
 
 
 
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