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    How would you approach this question?

    Which of the following contains the most chloride ions?[1 mark]
    A 10 cm3 of 3.30 × 10–2 mol dm–3 aluminium chloride solution
    B 20 cm3 of 5.00 × 10–2 mol dm–3 calcium chloride solution
    C 30 cm3 of 3.30 × 10–2 mol dm–3 hydrochloric acid
    D 40 cm3 of 2.50 × 10–2 mol dm–3 sodium chloride solution
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    A) Aluminium Chloride solution: AlCl3
    (10*3.3)/1000=0.033
    B) Calcium Chloride solution: CaCl2
    (20*5)/1000=0.100
    C) Hydrochloric acid: HCl
    (30*3.3)/1000=0.099
    D) Sodium Chloride solution: NaCl
    (40*2.5)/1000=0.100

    From what i can see it's going to be either CaCl2 or NaCl, and I kind of confused myself :/
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    (Original post by Libaan)
    A) Aluminium Chloride solution: AlCl3
    (10*3.3)/1000=0.033
    B) Calcium Chloride solution: CaCl2
    (20*5)/1000=0.100
    C) Hydrochloric acid: HCl
    (30*3.3)/1000=0.099
    D) Sodium Chloride solution: NaCl
    (40*2.5)/1000=0.100

    From what i can see it's going to be either CaCl2 or NaCl, and I kind of confused myself :/
    Almost there!
    Firstly, you just need to divide each one by 100, because the concentration is ___ x 10-2 moldm-3

    Then, just realise that, for example

    AlCl3 ---> Al3+ + 3Cl-

    So if you have 0.00033 mol of AlCl3 you're gonna end up with
    0.00033 x 3 = 0.00099 mol of Cl-

    Apply the same amount of reasoning to the other solutions and you'll find that CaCl2 has the highest amount of Chloride Ions


    You're not the OP I know, but it'll help both of you.
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    Thank you so much guys for your help
 
 
 
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