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    (Original post by Connor_leigh)
    'Boron trichloride is easily hydrolysed to form two different acids as shown in the following equation.
    Bcl3 + 3h20 makes(can't do an arrow) H3BO3+3HCl.
    Calculate the concentration in mol dm^-3 oh hydrochloric acid produced when 43,2g of boron trichloride are added to water to form 500cm^3 of solution. Give your answer to 3 significant figures'

    I've checked a mark scheme and it's saying 43.2/117.3. Can anyone tell me where the 117.3 comes from please?
    Its the Mr of BCl3

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    (Original post by samb1234)
    Its the Mr of BCl3

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    Thanks! I used the proton number of boron.... My Mr calculation of BCl3 came out wrong. Thats why i was so confused
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    Can someone also please explain why you times to moles of Hcl by 1000/500? Thanks in advance
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    (Original post by Connor_leigh)
    Can someone also please explain why you times to moles of Hcl by 1000/500? Thanks in advance
    What's the question

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    (Original post by Connor_leigh)
    'Boron trichloride is easily hydrolysed to form two different acids as shown in the following equation.
    Bcl3 + 3h20 makes(can't do an arrow) H3BO3+3HCl.
    Calculate the concentration in mol dm^-3 oh hydrochloric acid produced when 43,2g of boron trichloride are added to water to form 500cm^3 of solution. Give your answer to 3 significant figures'

    I've checked a mark scheme and it's saying 43.2/117.3. Can anyone tell me where the 117.3 comes from please?
    What's the question
    Here
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    (Original post by Connor_leigh)
    Here
    you work out number moles of boron trichloride BrCl3 so that's what the 117 thing was about.
    then you look at the equation
    what is the mole ratio?
    then work out the conc of Hcl by rearranging moles=conxvol
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    Anyone need any help with anything? Stuck at a family friends and all my revision stuff is at home

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    i despise isas/empas, iv done the chemistry and physics as isas, got 31 on chemistry=(((( and 40 on physics which is okay i guess. Now i have to do an empa for chemistry which i hear are very difficult anyone have any general tips on doing it and ways to revise.
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    Does anybody know what 32 marks in the AS edexcel chemistry controlled assessment is? Is it a C?
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    (Original post by TheonlyMrsHolmes)
    Does anybody know what 32 marks in the AS edexcel chemistry controlled assessment is? Is it a C?
    I think that would be yes. I know that a is 37 so I reckon b is probably 34ish

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    (Original post by samb1234)
    I think that would be yes. I know that a is 37 so I reckon b is probably 34ish

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    Oh well, whats done is done, I found the experience painful, I just cannot to practicals. Thankyou for replying!
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    (Original post by TheonlyMrsHolmes)
    Oh well, whats done is done, I found the experience painful, I just cannot to practicals. Thankyou for replying!
    Any of the practicals in particular that didnt go so well?

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    (Original post by samb1234)
    Any of the practicals in particular that didnt go so well?

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    My titration one but I suspected that since I was holding my thumb under the glass pipette to stop the HCL dripping out :rolleyes: and my non-organic. I lost 4 marks in both :eek:
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    AQA please add me
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    Ocr isa quantative; titrations? Please help
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    Hey all

    If you need any extra revision materials - questions (+ answers!) and notes - check out my website www.scienceskool.co.uk All totally free, no ads and can all be viewed offline once downloaded of course. I hope you find it useful.

    Alex
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    The first five successive ionization energies of an element, X, are shown in the tablebelow.

    Ionization energy: first second third fourth fifth
    Value/ kJ mol–1 590 1100 4900 6500 8100

    Which ion is X most likely to form when it reacts with chlorine?
    A X+
    B X2+
    C X3+
    D X4+

    HELP PLEASE!
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    (Original post by alevels2k15)
    The first five successive ionization energies of an element, X, are shown in the tablebelow.

    Ionization energy: first second third fourth fifth
    Value/ kJ mol–1 590 1100 4900 6500 8100

    Which ion is X most likely to form when it reacts with chlorine?
    A X+
    B X2+
    C X3+
    D X4+

    HELP PLEASE!
    I'm assuming it's B because there's a huge jump between the second and third ionisation energy.
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    (Original post by frozo123)
    I'm assuming it's B because there's a huge jump between the second and third ionisation energy.
    Yeah! the answer is B
    BUT how?
    i dont understand how to go about answering this question
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    (Original post by alevels2k15)
    Yeah! the answer is B
    BUT how?
    i dont understand how to go about answering this question
    well what do you know about ionisation energies atm?
 
 
 
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