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-   -   How many moles of NaOH are needed to neutralize the acid? (https://www.askmehelpdesk.com/showthread.php?t=408627)

  • Oct 22, 2009, 08:53 AM
    sarah1004
    How many moles of NaOH are needed to neutralize the acid?
    A 38mL solution 0.026M solution of HCl reacts with a 0.032M NaOH.

    HCl+NaOH=NaCl+H2O
    number of moles of HCl originally present is 0.000988moles.

    how many moles of NaOH are needed to neutralize the acid???
    Please show me how to do this and , Please give me answer. Please..
  • Oct 22, 2009, 09:58 AM
    Unknown008

    I already told you how to do it. Now, do your part. Post what you think the answer is, we'll correct if required. We are not allowed to give you answers directly, but only directions, those are the forum rules, in case you didn't know.

    https://www.askmehelpdesk.com/chemis...id-408452.html
  • Oct 22, 2009, 10:07 AM
    sarah1004
    b) Using your equation, you'll have the molar ratio of the reagents required. You'll see that one mole of acid reacts with one mole of alkali.

    So, (0.026/1000) * 38 mol of acid will react with how many moles of alkali?

    how many moles of NaOH are needed to neutralize the acid?

    so, you mean answer is just 0.000988moles again??
  • Oct 22, 2009, 10:09 AM
    Unknown008

    Exactly! You see when you try?

    Now for the third part, try solving it.
  • Oct 22, 2009, 10:11 AM
    sarah1004
    calculate the volume of the NaOH required to react completely with the acid

    what equation needs to solve this one?
  • Oct 22, 2009, 10:16 AM
    Unknown008

    Ok, you know now you need 0.000998 mol of NaOH.

    You have 0.032 mol of NaOH in 1000 mL
    To have one mole, you need (1000/0.032) mL
    How much volume do you need for 0.000988 mol?

    Like 2 apples cost $10
    1 apple cost (10/2) = $5
    1/2 apple cost (10/2) * (1/2) = $2.50

    It's all proportions!
  • Oct 22, 2009, 10:19 AM
    sarah1004
    So answer is 31250??

    I am so sorry I just came to america few months ago.
    I am not very good at english..

    Thanks!
  • Oct 22, 2009, 10:22 AM
    Unknown008

    Hmmm, not quite.

    You have the volume you need for 1 mole.
    Try again, this time you need to find for 0.000988 mol, the amount of moles you required before.

    By the way, if you aren't quite at ease with english, which language do you speak with more ease? I can do with french.
  • Oct 22, 2009, 10:23 AM
    sarah1004
    I am speaking Korean..
    Could you please show me equation?
    Thanks!
  • Oct 22, 2009, 10:59 AM
    Unknown008

    There is no equation for this!

    You only use your logic!

    Ok, I'll give another example:

    5 moles of HCl are in 50 mL

    How in how much volume is there 0.23 moles of HCl?

    5 moles -> 50 mL
    1 mole -> 50/5 = 10 mL
    0.23 moles -> 10*0.23 = 2.3 mL

    Now, do the same with your problem:

    0.032 moles -> 1000 mL
    1 mole -> 1000/0.032 = 31250 mL
    0.000988 mol -> ?
  • Oct 22, 2009, 11:07 AM
    sarah1004
    31250/0.000988=3.16x10^7

    like this?.
  • Oct 22, 2009, 11:12 AM
    Unknown008

    Nope. Look back at my example. How did I get the volume of HCl for 0.23 moles?
  • Oct 22, 2009, 11:15 AM
    sarah1004
    1000/0.000988=1.01x10^6

    like this is correct?.

    Thank you!
  • Oct 22, 2009, 11:20 AM
    Unknown008

    No again.

    The answer is:

    0.032 moles -> 1000 mL
    1 mole -> 1000/0.032 = 31250 mL
    0.000988 mol -> 31250*0.000988 = 30.875 mL

    Just in case, '*' means multiplication.
  • Oct 22, 2009, 11:27 AM
    sarah1004
    Oh...
    now I got it thank you so much...

    So, we can conclude like it

    A 38mL solution 0.026M solution of HCl reacts with a 0.032M NaOH.

    a)write a balanced chemical reaction for the above process.
    HCl+NaOH=NaCl+H2O

    b)calculate the number of moles of HCl originally present.
    (0.026moles/Liter)*(38mL/1)*(1Liter/1000mL)=0.000988moles.

    c)how many moles of NaOH are needed to neutralize the acid?
    (0.026/1000)*38=0.000988mloles

    d)calculate the volume of the NaOH required to react completely with the acid.
    31250*0.000988=30.875mL


    Can you check it out for me?
    Thank you sososo much
  • Oct 22, 2009, 11:28 AM
    Unknown008

    Well done! :)
  • Oct 22, 2009, 11:31 AM
    sarah1004
    Thank you
    Are you a teacher?
  • Oct 22, 2009, 10:24 PM
    Unknown008

    Nope, a student. Perhaps. At a slightly higher level than you...

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