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Homework Help: How many H+ ions in 0.050 ml

  1. Jun 20, 2016 #1
    Here is a problem that looked easy for me, but my answer differs from the textbook's one. Please, help me to see my mistake.

    How many H3O ions are present in one

    drop (0.050 mL) of pure water at 25 °C?

    Here is how I solved it:
    There are 1.0 x 10^-7 in one liter.
    We have 0.000050 liters, hence 0.00005 x 1.0 x 10^-7 = 5 x 10^-12

    The book gives 3 x 10^12

    Thank you!
  2. jcsd
  3. Jun 20, 2016 #2


    User Avatar

    Staff: Mentor

    You do understand the difference between number of moles and number of ions?
  4. Jun 20, 2016 #3
    Oh! What a shame ) Sorry. Yes. I have to multiply my moles 5 x 10^-12 by 6.022 x 10^23
    Thank you!
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