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help me wotk thru this chem q pwease.. watch

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    the pH values of aqeuous solns of some acis are as follows:

    0.1M HCl pH 1
    o.1M Ethanoic acid pH 2.9
    0.1M Chloroethanoic acid pH 1.9

    1, Calc the conc of H+ ions in the cholrothanoic acid soln with pH 1.9

    i did that got 0.0126

    but then the next part is wat is the conc of the choloroethanoate ions in this soln??!!
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    (Original post by Dust)
    the pH values of aqeuous solns of some acis are as follows:

    0.1M HCl pH 1
    o.1M Ethanoic acid pH 2.9
    0.1M Chloroethanoic acid pH 1.9

    1, Calc the conc of H+ ions in the cholrothanoic acid soln with pH 1.9

    i did that got 0.0126

    but then the next part is wat is the conc of the choloroethanoate ions in this soln??!!
    hmm
    ph= -log [H+]
    can you write the structural formula of chloroethanoate, i might be able to help you
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    thats it they havent given it on the exam paper
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    (Original post by Dust)
    the pH values of aqeuous solns of some acis are as follows:

    0.1M HCl pH 1
    o.1M Ethanoic acid pH 2.9
    0.1M Chloroethanoic acid pH 1.9

    1, Calc the conc of H+ ions in the cholrothanoic acid soln with pH 1.9

    i did that got 0.0126

    but then the next part is wat is the conc of the choloroethanoate ions in this soln??!!
    ok [H+][A-]/[HA]
    fill in the figures we know [0.0126][A-]/[0.1]
    rearrange [A-] =[0.0126]/[0.1]

    i was just working that through as it went...but just had a thought, in a weak acid don't you presume that the concentration of the H+ and A- is equal? so in that case the concn will be the same as for hydrogen ions?
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    (Original post by allisandro)
    ok [H+][A-]/[HA]
    fill in the figures we know [0.0126][A-]/[0.1]
    rearrange [A-] =[0.0126]/[0.1]

    i was just working that through as it went...but just had a thought, in a weak acid don't you presume that the concentration of the H+ and A- is equal? so in that case the concn will be the same as for hydrogen ions?
    that sounds right
    how many marks is that question? if its one mark then it will b e the same. if it says state the value of the concn then it means that you just state it, but if they say calculate, it means there is some calculation to do
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    lol omg of course!

    so the next bit is assuming that the conc of choloroethanoic acid may be taken as 0.1M calc the Ka for ethanoic acid
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    (Original post by Dust)
    lol omg of course!

    so the next bit is assuming that the conc of choloroethanoic acid may be taken as 0.1M calc the Ka for ethanoic acid
    erm i guess?
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    lol i need to make up last yrs marks with a A on this paper...
    hmmm....
 
 
 
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