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Homework Help: Very basic chemistry questions

  1. Feb 8, 2004 #1
    I'm really no good at Chemistry, and these are practice questions to our test tomorrow (with no answers, which is pretty worthless )

    5. A 10mL solution of 1.0M NaOH is required to react completely with how many mL of a 0.25M solution of H2SO4?
    a) 20mL
    b) 40mL
    c) 160mL
    d) 4mL
    e) 10mL

    I think D, though I'm probably wrong.

    10. A mixture of 2.00g of NaCl and enough water (H2O) to result in 100 mL of solution will have what molarity?
    a) 2.00M
    b) 0.034M
    c) 0.058M
    d) 0.34M
    e) 0.58M

    I dont even know where to start with this one :(

    11. In which of the following name-formula pairs do both items correctly name the same compound?

    a) SeCl6 - Selenium hexachloride
    b) Br2O5 - Dibromide pentoxide
    c) F2O7 - Fluorine septoxide
    d) Ba(OH)2 - Barium dihydrate
    e) P4S10 - Quatraphosphoric decasulfide

    I have it narrowed down between A and B, they both seem to work, though im leaning towards A?

    20. In which of the following aqueous mixtures will no chemical reaction occur?
    a) Hg(NO3)2 (aq) + Na2(SO4) (aq) ->
    b) Na3(PO4) (aq) + Sr(NO3)2 (aq) ->
    c) Na2CO3 (aq) + Ba(OH)2 (aq) ->
    d) (NH4)2S (aq) + CaI2 (aq) ->
    e) ZnSO4 (aq) + MgCl2 (aq) ->

    No idea, think it's E though?

    21. In the following reaction: 2HBr (aq) + Ba(OH)2 (aq) -> BaBr2(?) + 2H2O(?)
    a) Ba(OH)2 is a weak base
    b) H2O is a spectator ion in this reaction
    c) HBr is a strong acid and Ba(OH)2 is a strong base
    d) HBr is a weak acid
    e) BaBr2 is insoluble and precpitates

    Think it's C

    That's all for the moment, thanks :/
     
  2. jcsd
  3. Feb 8, 2004 #2
    what am I, a leper or something? :D
     
  4. Feb 8, 2004 #3

    ShawnD

    User Avatar
    Science Advisor

    Just make a formula that will cancel all the units and it will work out fine. ALWAYS WRITE THE UNITS when you are doing anything in chemistry.


    I got 40mL, which is B

    I got 0.348M which is close to D

    The answer is A (or at least I think it is).

    This question I don't know. My redox table doesn't list most of those (like SO4, NO3, Sr, CO3).

    I too think it's C.

    and yes, you are a leper
     
  5. Feb 9, 2004 #4
    Nope u are using molarity equation instead of normality
    it should be

    N1V1=N2V2
    So u have 10*1=2*0,25*V2

    V2= 10/0,5=20mL
     
    Last edited: Feb 9, 2004
  6. Feb 9, 2004 #5

    ShawnD

    User Avatar
    Science Advisor

    Oh yeah, 2 to 1 ratio. Sorry about that. Subscripts DO make it easier to read :D

    Do you know what the answer to that reaction one is?
     
    Last edited: Feb 9, 2004
  7. Feb 9, 2004 #6
    ty very much, I got it.. I had my test today, I hope I did well
     
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