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dddan

  • 2 years ago

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?

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  1. ethayer
    • 2 years ago
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    is the first one in mL too?

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

  3. ethayer
    • 2 years ago
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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)

  4. ethayer
    • 2 years ago
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    let me know what you get.

  5. dddan
    • 2 years ago
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    alright

  6. ethayer
    • 2 years ago
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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.

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

  8. ethayer
    • 2 years ago
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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?

  9. ethayer
    • 2 years ago
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    ^sorry, .06M not .6

  10. dddan
    • 2 years ago
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    .25L and .5L

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

  12. dddan
    • 2 years ago
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    i got .15 and 0.0415....

  13. ethayer
    • 2 years ago
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    the first one should be .015...

  14. dddan
    • 2 years ago
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    alright hold on

  15. dddan
    • 2 years ago
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    ya your right its .015

  16. ethayer
    • 2 years ago
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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?

  17. dddan
    • 2 years ago
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    alright then i got .075 as final answer

  18. ethayer
    • 2 years ago
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    correct! .0565mol/ .75L

  19. dddan
    • 2 years ago
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    thanks so much!!!

  20. ethayer
    • 2 years ago
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    your very welcome!

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