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wondering_

  • 2 years ago

How many milligrams of C atoms are in 2.04 x 10^20 molecules of ethanol?

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  1. zepp
    • 2 years ago
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    Ethanol: \(\large \text{C}_2\text{H}_6\text{O}\)

  2. zepp
    • 2 years ago
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    So first question, how many moles does 2.04 x 10^20 molecules represent?

  3. wondering_
    • 2 years ago
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    its not CH(Sub 6)O?

  4. wondering_
    • 2 years ago
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    why did u give Carbon2?

  5. zepp
    • 2 years ago
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    Because that's the formula for Ethanol

  6. zepp
    • 2 years ago
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    It's a 2-carbon alcohol.

  7. wondering_
    • 2 years ago
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    \[(6.02 \times 10^{23})(2.04 \times 10^{20})?\]

  8. wondering_
    • 2 years ago
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    oh ok

  9. zepp
    • 2 years ago
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    That's incorrect; \[\large 1 \text{ mole}= 6.02×10^{23}\]

  10. zepp
    • 2 years ago
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    \[\large ? \text{ mole}=2.04×10^{20}\]

  11. zepp
    • 2 years ago
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    That's a proportion and you should have this: \(\LARGE \frac{2.04×10^{20}}{6.02×10^{23}}\)

  12. wondering_
    • 2 years ago
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    oh so its divide instead of multiply?

  13. zepp
    • 2 years ago
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    Yes, that's algebraic manipulation.

  14. zepp
    • 2 years ago
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    Once you get that, you'll get the number of moles this quantity of molecules represent, are afterward, you may convert that easily to its mass through the molar mass.

  15. wondering_
    • 2 years ago
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    |dw:1349138080842:dw|

  16. zepp
    • 2 years ago
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    Why 1000?

  17. wondering_
    • 2 years ago
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    for milligrams?

  18. zepp
    • 2 years ago
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    Our units are in moles...

  19. zepp
    • 2 years ago
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    \[\large \frac{1 \text{ mole}}{6.02*10^{23} \text{ atoms}}=\frac{x \text{ mole}}{2.04 * 10^{20}\text{ atoms}}\]Multiply both sides by 2.04*10^20\[\large \frac{2.04*10^{20}\text{ atoms}*1 \text{ mole}}{6.02*10^{23} \text{ atoms}}=x \text{ mole}\]

  20. zepp
    • 2 years ago
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    atoms and atoms simplify out, leaving the mole on both sides.\[\large \frac{2.04*10^{20}}{6.02*10^{23}}\text{mole}=x \text{ mole}\]

  21. wondering_
    • 2 years ago
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    ok i see

  22. wondering_
    • 2 years ago
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    i got .0003 correct?

  23. zepp
    • 2 years ago
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    You'll get as answer: \(\large x\text{ moles}\) Now you may proceed to transform this using \(\LARGE n=\frac{m}{M}\), where \(\large \text{n}\) is the number of moles, \(\large \text{m}\) is the mass in \(\large \textbf{grams}\) (so you'll need to retransform it into milligrams as you're asked to do) and \(\large \text{M}\) is the molar mass.

  24. wondering_
    • 2 years ago
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    Molar mass is 46.07?

  25. zepp
    • 2 years ago
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    Yes

  26. wondering_
    • 2 years ago
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    well for ethanol it self right?

  27. wondering_
    • 2 years ago
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    would i multiply that by .0003

  28. zepp
    • 2 years ago
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    Exact.

  29. wondering_
    • 2 years ago
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    46.68->46.7 sorry

  30. wondering_
    • 2 years ago
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    so i got .0140 because i used 46.68*.0003

  31. wondering_
    • 2 years ago
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    thats just grams right?

  32. zepp
    • 2 years ago
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    Yep

  33. wondering_
    • 2 years ago
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    .0140 x 10^-3 ?

  34. zepp
    • 2 years ago
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    Good, now you'll need to set up another proportion:\[ \frac{\text{Mass of Carbon in 1 mole of Ethanol}}{\text{Molar mass of Ethanol}}=\frac{\text{Mass of Carbon (Unknown) }}{\text{Mass of the Ethanol given to you}}\]

  35. wondering_
    • 2 years ago
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    (?/46.68)=(?/.0140x10^-3?)

  36. zepp
    • 2 years ago
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    Mass of carbon in 1 mole of ethanol is a known number, 2*Molar mass of carbon, 12, 2*12 = 24.

  37. wondering_
    • 2 years ago
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    oh ok i see where you got that from

  38. wondering_
    • 2 years ago
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    (24/46.68) = (?/.0140x10^-3?)

  39. wondering_
    • 2 years ago
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    was i correct on the second half too?

  40. zepp
    • 2 years ago
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    I don't know, I didn't push the values in my calculator, I've shown you how to do these kind of problem, all the other mathematical manipulations/calculations should be done by you; the right method is shown so you can take down any question that looks like this.

  41. wondering_
    • 2 years ago
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    I was asking about for the mass of the ethanol that the answer i found before right?

  42. zepp
    • 2 years ago
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    Like I said, I don't know :)

  43. wondering_
    • 2 years ago
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    Ok so now i simple mult across top and bottom and cancel out to get my answer

  44. wondering_
    • 2 years ago
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    simply*

  45. wondering_
    • 2 years ago
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    i think i have it

  46. wondering_
    • 2 years ago
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    thank you

  47. zepp
    • 2 years ago
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    np

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