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    (Original post by mbb123mbb)
    For the last question, can't quite remember what it was, but it was 3.2 moles of N2 formed right?
    Yes I'm fairly certain you formed 3.2 moles in total, (3 from the first reaction and 0.2 from the second). You then multiply by this by Avogadro's constant to find the number of molecules I think and the answer was like 1.93 x 10^24.
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    Thanks for the unofficial markscheme.
    I wanna know how many marks i dropped but i dont remember the marks for the questions so that sucks. But i know i did quite bad and i found it really hard
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    I think I lost around 15-17 marks and hopefully that will be a low A. Now that I finished all my paper 1 exams, I really know what I did wrong for each subject. At C1 I had timing problems and then I improved in C2 and I had 30 mins left. In this exam I lost marks on wasting time on 1 mark question. Now I'm going to work real hard to get high marks for Chem.
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    (Original post by DaVinciGirl)
    What's the observation when colourless Potassium iodide and Sodium Chloride are mixed and what reaction occurred for this to be seen?
    There was a brown solution seen, as Iodine ion was reduced to Iodine.
    I thought it'd be grey/black solid since iodine isn't a liquid at room temp (in fact it doesn't really exist as a liquid)?? idk though
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    (Original post by DaVinciGirl)
    I think I lost around 15-17 marks and hopefully that will be a low A. Now that I finished all my paper 1 exams, I really know what I did wrong for each subject. At C1 I had timing problems and then I improved in C2 and I had 30 mins left. In this exam I lost marks on wasting time on 1 mark question. Now I'm going to work real hard to get high marks for Chem.
    Same I think I lost around 15-20 haha. Hopefully the grade boundaries are low, I wasted so much time on the first 3 one markers!!
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    How many marks was the justification and improvement of titration question?
    Also I got 1740000 for the speed of the particle, would they give a range of answers as there was a lot of rounding that could have been done?
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    (Original post by LightAtTheEnd)
    Yes I'm fairly certain you formed 3.2 moles in total, (3 from the first reaction and 0.2 from the second). You then multiply by this by Avogadro's constant to find the number of molecules I think and the answer was like 1.93 x 10^24.
    Yup, cheers!
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    (Original post by DaVinciGirl)
    If you know anymore questions or answers please reply and the number of marks.
    What is the full electronic configuration of Al? 1s2,2s2,2p6,3s2,3p1

    What is the full electronic configuration for Cr+3? 1s2,2s2,2p6,3s2,3p6,3d3

    What is the formula of the ion with same electronic configuration of Krypton?
    Sr2+ (strontium)

    What compound has a +2 and -3 ions and has the same number electrons as Argon?
    Ca3P2

    Which ion has a smaller atomic radius Mg2+ or Na+?
    Mg 2+
    because has the same number of electrons, same shielding but more protons. So greater nuclear charge and attraction for outer electrons.

    What is the first ionisation energy of Na?
    Na (g) --> Na+ (g) + e-
    Diagram-Mark where the Mg or was it Si?
    Was and then mark the point where Sulphur was on the First ionisation graph.
    Mg/Si should have been above so the line was increasing.
    Sulphur should have been below Phosphorus but above Silicon.

    Why does Sulphur have a different first ionisation energy compared to Phosphorus?
    -Both have same shielding and in the same orbital the 3p orbital
    -Sulphur is paired with an electron in the 3p orbital whilst Phosphorus isn’t
    -There’s repulsion between the negatively charged electrons
    -So electrons are easier to remove

    What is the method of making a standardised solution of 250cm^3? (6 marks)
    -Weigh out known mass on weighing boat using a mass scale
    -Remember to deduct the mass of the weighing boat to find the exact mass of the solid. (or zero the scale mass)
    EDIT: You may not need this part as you've been told the known mass
    -Then transfer the contents into a beaker. Use distilled water to make sure all solids are in the beaker.
    -Then add bit more distilled water
    -Stir with a glass rod to make sure it's all mixed
    -Then pour solution into a Volumetric flask using a funnel
    -Clean the funnel with distilled water
    -Then fill the volumetric flask to the 250cm^3 mark. At near the mark use a pipette to add water dropwise and until meniscus is on the mark line.
    Then place stopper on it. Twist the volumetric flask a few times to ensure it's all mixed.

    Find mean titre value.
    Ignore the first number as it was the rough one when calculating mean.
    EDIT: You were only supposed to use 2 values that are 0.1 part when calculating mean.

    What was the concentration of the solution.

    Student titrated, what should she to improve her methods so there's a smaller percentage uncertainty?
    -Titrate a greater volume of solution
    -Why? So there's a greater value as percentage uncertainty= uncertainty/value *100. Bigger volume means there's a greater titre value.

    Why does Bromine have lower boiling point than Magnesium?
    -Bromine has a simple molecular structure.
    -There’s weak Van der Waals forces between molecules.
    -So smaller amount of energy needed to break these forces.
    -Magnesium has a metallic lattice.
    -It has many strong metallic bonds.
    -Bonds formed from the strong attraction between positiveions and delocalised electrons.
    -The metallic bonds are stronger than the Van der Waals forces

    How do the ions get accelerated, detected by ToF and how abundanceis measured?
    - Accelerated by negative electric field
    -The ions reach the detector and generate a small current, which is fed to a computer for analysis. The current is produced by electrons transferring from the detector to the positive ions. The size of the current is proportional to the abundance of the species.

    Calculation to find mass of one ion.
    1/Avogadro constant * mass. Then divide by 1000 to put it in Kg.
    Using kinetic energy, find velocity.
    Starts with 1........ Quite a large number.

    Draw the spectrum of Br2 with two isotopes of equal abundance.
    Attachment 539511

    Suggest why Magnesium has a longer melting point than Bromine. (Something like that?)
    -It has much more bonds than Bromine. So more bonds are needed to be broken when melting.
    a) Calculate the mass of Ammonia in Q?
    Basically use the ideal gas equation and usethe temp given, multiply the pressure by 1000 to convert it to SI Units, divide the volume by a million to convert to m^3 . Then use everything given to find the number of moles in Ammonia. Then find the mass of Ammonia using the mr.
    b) Calculate the volume in P given that the temperature decreased by 5 degrees and the total pressure is 75kPa?
    -Find volume of the whole system with the new values and use moles from previous question
    -Then subtract from the volume of Q given.

    Draw NH3 and AlCl3 and write the bonding angle.
    NH3- 1 Lone pair and 3 bonding pair. Should have drawn a trigonal pyrimidal.
    Bond angle- 107

    AlCl3- 3 bonding pair so Trigonal Planar
    Bond angle- 120

    What type of bond between NH3 and AlCl3 to make 3HNAlCl3?
    Dative covalent
    Electron pair donated from NH2 to AlCl3.

    What is the half equation of Chlorate(I) into Chlorine?
    2ClO- + 4H+ +2e- ---> Cl2 + 2H20

    What is the redox equation of Sodium Chlorate(I) and HCl?
    I have no idea.

    What's the observation when colourless Potassium iodide and Sodium Chloride are mixed and what reaction occurred for this to be seen?
    There was a brown solution seen, as Iodine ion was reduced to Iodine.

    Question on Anhydrous Magnesium Chloride and Anhydrous Barium Chloride mixture. Water was added and Sulphuric acid too. White precipitate was formed. What was this an find percentage of Magnesium in mixture?
    Barium Sulphate.
    Calculation:

    Multiple Choices:
    -Brown Colour is from the Reactant and forward is exothermic.
    -Empirical of hydrocarbon with 9/11th Carbon- C3H8
    -Doubts about biggest dipole. I put down BF3 and checked in my CGP book and states that bonds with electronegativity differences would make a dipole. Others argue that its Carbon one because BF3 is not polar.
    -Group 2's ionisation energy decreases downwards
    -There's 50cm^3 of gas in the end.
    -Gold is 19.3
    -SiO2 was Macromolecular
    -Balance was 4:7
    -The reducing agent was C204
    -How much sulphuric acid needed? D
    -Heavier isotope took longer in ToF
    -H2 Molecules was 1.81* 10^24
    Right, for the second PV=nrt question youve said you work out the volume of the whole system but surely since the system was closed it would be the same as in the previous question?

    I used PVnrt twice so I first used it on Q to work out the moles of the gas in Q, then subtracted from moles in previous question to find moles in P. Then I used the moles of P to do PV = nrt on P giving me 340cm^3 to 2 sf idk if thats right cause it seemed like a lot to do for 3 marks but im pretty certain the volume of the whole system stayed constant.

    Also for the velocity of the ion I got 12.1ms-1

    And for the calculation for the last one I worked out the moles of the percipitate them had (cant remember what it was) then I worked out the moles of something else I think it was moles of BaCl2 not sure. Then using that I worked out the mass of the BaCl2 in the start then took away from start mass of sample to get mass of MgCl2 then as a percentage I think I got 34.3 or something like that
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    (Original post by SM-)
    How many marks was the justification and improvement of titration question?
    Also I got 1740000 for the speed of the particle, would they give a range of answers as there was a lot of rounding that could have been done?
    I got that too!!! )
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    the first U im expecting comes from chem

    i flopped so badly ....
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    (Original post by SM-)
    How many marks was the justification and improvement of titration question?
    Also I got 1740000 for the speed of the particle, would they give a range of answers as there was a lot of rounding that could have been done?
    How did you get that? I got like 12.1 fs
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    (Original post by DaVinciGirl)
    I think I lost around 15-17 marks and hopefully that will be a low A. Now that I finished all my paper 1 exams, I really know what I did wrong for each subject. At C1 I had timing problems and then I improved in C2 and I had 30 mins left. In this exam I lost marks on wasting time on 1 mark question. Now I'm going to work real hard to get high marks for Chem.
    That's unlikely! Don't forget to count in method marks
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    I got 1740 ms^-1 for speed of particle

    Posted from TSR Mobile
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    ok, so im on a 50/50 with this paper did anyone else mess up totally on the titration question???????
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    Do you reckon 50/80 will be a C? 😁🙏🏻
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    what do you guys think the grade boundaries will be? And how much makrs was the question about Br 2+ woth, where u had to draw it etc
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    (Original post by ljgbjnhnoilk)
    ok, so im on a 50/50 with this paper did anyone else mess up totally on the titration question???????
    I think so but tbh I can't remember what I got or what was right 😭😂
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    (Original post by saahil0987)
    How did you get that? I got like 12.1 fs
    You covert the Mr to kg from g then divide by avagrados constant so mass of one particle found, then you just sub into equation
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    also, what percentage did u guys get for the question with magnesium and barium chloride
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    (Original post by hbaig27)
    i left 0.69g, i got the next part wrong tho
    how many marks was this question with the barium sulphate?
 
 
 
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