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OCR A2 CHEMISTRY F324 and F325- 14th and 22nd June 2016- OFFICIAL THREAD watch

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    (Original post by MrZebraCookie)
    Were there any equations or compounds (except the ionic equation on the last page) where it was necessary to put state symbols?
    The Born-Haber cycle


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    (Original post by GetOverHere)
    So did I, it's fine because you'd be reacting an acid and an alkali, getting a salt (Cu(HCOO)2) and water.


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    reckon they'd allow copper sulphate reacting to form sulphuric acid and the salt?
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    (Original post by Jm098)
    reckon they'd allow copper sulphate reacting to form sulphuric acid and the salt?
    TBH I think because they said any copper compound, as long as copper sulfate and methanoic acid react to form that, it should be OK. The only thing is that you've made another acid in the process so I'm not sure if that might be marked wrong due to the fact that making an acid would influence the titration.


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    For the entropy question, I think I used the lattice enthalpy as delta H. How many marks would this lose?
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    (Original post by GetOverHere)
    TBH I think because they said any copper compound, as long as copper sulfate and methanoic acid react to form that, it should be OK. The only thing is that you've made another acid in the process so I'm not sure if that might be marked wrong due to the fact that making an acid would influence the titration.


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    ok thank you
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    i find out that i mess up the concepts of cis and trans......
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    (Original post by GetOverHere)
    The Born-Haber cycle


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    Awesome, thanks
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    (Original post by GetOverHere)
    So did I, it's fine because you'd be reacting an acid and an alkali, getting a salt (Cu(HCOO)2) and water.


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    Unfortunately no. Correct me if I'm wrong, but the question wanted Cu2+ ions, and Cu(OH)2 is a solid in water(precipitate) so wouldn't work:/
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    That question on oxidising and reducing agent was 6 marks and I def got that reducing equation wrong because I said it would react with 3 - 6 redox systems instead of just one.
    How many marks do people think thats worth?
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    (Original post by Jm098)
    reckon they'd allow copper sulphate reacting to form sulphuric acid and the salt?
    That's what I did. No reason why not I don't think!
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    Does anyone remember what happens with chemical shift when agno3 is added?
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    (Original post by cr7alwayz)
    For using a calculation to explain why K2SO4 can dissolve at 25oC was the entropy change 0.02 or something which is positive so the reaction is feasible?
    I think You had to show that G was negative using the free energy equation, making the reaction feasible at 25oC bc just because entropy is positive, doesn't mean it's feasible as enthalpy and temperature also contribute to overall feasibility ☺️
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    (Original post by nimoooooooo)
    Does anyone remember what happens with chemical shift when agno3 is added?
    there are no protons and carbons.
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    (Original post by Cal 1)
    That's what I did. No reason why not I don't think!
    Cool man.. I think was gonna put the hydroxide but realised it's a blue precipitate hahaha
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    (Original post by Cal 1)
    Unfortunately no. Correct me if I'm wrong, but the question wanted Cu2+ ions, and Cu(OH)2 is a solid in water(precipitate) so wouldn't work:/
    I went for the ol' CuCO3, which is also insoluble but I think it would get the mark no? You want to end up with the Cu(HCOO-), because the carbonate and the acid would definitley react, even if it was solid before
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    (Original post by Cal 1)
    Unfortunately no. Correct me if I'm wrong, but the question wanted Cu2+ ions, and Cu(OH)2 is a solid in water(precipitate) so wouldn't work:/
    so Cu(OH)2 wont react with methanoic acid to form the Cu(HCOO)2 salt?
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    (Original post by Ame12345)
    I think You had to show that G was negative using the free energy equation, making the reaction feasible at 25oC bc just because entropy is positive, doesn't mean it's feasible as enthalpy and temperature also contribute to overall feasibility ☺️
    What was the enthalpy? Can you remember?
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    It is lattice enthalphy isn't it?
    (Original post by MrZebraCookie)
    For the entropy question, I think I used the lattice enthalpy as delta H. How many marks would this lose?
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    (Original post by Cal 1)
    Unfortunately no. Correct me if I'm wrong, but the question wanted Cu2+ ions, and Cu(OH)2 is a solid in water(precipitate) so wouldn't work:/
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    (Original post by smileez_101)
    so Cu(OH)2 wont react with methanoic acid to form the Cu(HCOO)2 salt?
    CuCO3
 
 
 
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