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dddan

please help!; Assuming additivity of volumes, what is the concentration of KBr(in moles/L) in a solution prepared by mixing 2.50x10^2 of 0.0600 Molarity of KBr with 5.00x10^2 ml of 0.0830 Molarity?

  • one year ago
  • one year ago

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  1. ethayer
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    is the first one in mL too?

    • one year ago
  2. dddan
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    yea the 2.50x10^2 is in ml

    • one year ago
  3. ethayer
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    I think this is how you do it. 1st: change the mL into L (since M is in mol/L) 2nd: calculate the number of moles of KBr in each solution (M * L from above) 3rd: add the 2 numbers for moles together 4th: add the 2 numbers for volume together 5th: divide since you now have total moles and total volume (M = moles/L)

    • one year ago
  4. ethayer
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    let me know what you get.

    • one year ago
  5. dddan
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    alright

    • one year ago
  6. ethayer
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    just a way to check, your answer should be in-between the two given molarities since you are mixing them together and it should be a little closer to the larger molarity since you start with more of it.

    • one year ago
  7. dddan
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    alright i got a 5.2 Molarity does this sound right?

    • one year ago
  8. ethayer
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    try again. It should be between .6M and .083M since those are the values you started with and you are mixing the same compound. What did you get for your 2 new volumes?

    • one year ago
  9. ethayer
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    ^sorry, .06M not .6

    • one year ago
  10. dddan
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    .25L and .5L

    • one year ago
  11. ethayer
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    great! now what about for the moles of KBr found in each solution (molarity * liters = moles)?

    • one year ago
  12. dddan
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    i got .15 and 0.0415....

    • one year ago
  13. ethayer
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    the first one should be .015...

    • one year ago
  14. dddan
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    alright hold on

    • one year ago
  15. dddan
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    ya your right its .015

    • one year ago
  16. ethayer
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    alright! now when you add up your volumes what do you get? also what do you get when you add up the moles?

    • one year ago
  17. dddan
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    alright then i got .075 as final answer

    • one year ago
  18. ethayer
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    correct! .0565mol/ .75L

    • one year ago
  19. dddan
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    thanks so much!!!

    • one year ago
  20. ethayer
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    your very welcome!

    • one year ago
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