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Thread: Question about Moles

  1. #1 Question about Moles 
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    If a question comes along that asks you to calculate the quantity of sucrose and you can do that very easily but what if it had 5 moles of carbon atoms , how about 2 moles of carbon atoms? I'm stomped there

    Thanks in advance~


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  3. #2  
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    Set up a ratio and use dimensional analysis. Since sucrose is C12H22O11, for every 12 carbon atoms you have 1 sucrose molecule.


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  4. #3  
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    Quote Originally Posted by brushman
    Set up a ratio and use dimensional analysis. Since sucrose is C12H22O11, for every 12 carbon atoms you have 1 sucrose molecule.
    So find it for 1 sucrose molecule and then divide by 6?
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  5. #4  
    Geo
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    1 mole of Carbon atoms has a mass of 12g. 5 moles will be 60g.

    The Molar mass of sucrose is the sum of the constituent atomic masses. C=12 H=1 O=16.

    Mm=n
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  6. #5  
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    Quote Originally Posted by Geo
    1 mole of Carbon atoms has a mass of 12g. 5 moles will be 60g.

    The Molar mass of sucrose is the sum of the constituent atomic masses. C=12 H=1 O=16.

    Mm=n
    So actually my formula will be C5 h22 O11 or are you telling me something else?
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  7. #6  
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    Quote Originally Posted by Lightz

    So actually my formula will be C5 h22 O11 or are you telling me something else?
    He's telling you something else.

    sucrose is C12 H22 O11
    The Molar mass of sucrose is the sum of the constituent atomic masses.
    C=12 H=1 O=16.
    you need to establish this bit first ...
    what is the mass of 1 mol of sucrose in grams?
    how many mol of C, H, and O respectively are in 1 mol sucrose?

    what if it had 5 moles of carbon atoms
    1 mole of Carbon atoms has a mass of 12g
    then, whether you want your answer in moles or in grams,
    you define your ratio ...
    Nature abhors perfection; cats abhor a vacuum.

    "I don't know; I'm making it up as I go ..." Dr H Jones (Jr).
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  8. #7  
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    Quote Originally Posted by Cran
    Quote Originally Posted by Lightz

    So actually my formula will be C5 h22 O11 or are you telling me something else?
    He's telling you something else.

    sucrose is C12 H22 O11
    The Molar mass of sucrose is the sum of the constituent atomic masses.
    C=12 H=1 O=16.
    you need to establish this bit first ...
    what is the mass of 1 mol of sucrose in grams?
    how many mol of C, H, and O respectively are in 1 mol sucrose?

    what if it had 5 moles of carbon atoms
    1 mole of Carbon atoms has a mass of 12g
    then, whether you want your answer in moles or in grams,
    you define your ratio ...
    1 mol of sucrose is roughly 342 grams
    Wait in one mol of sucrose, there are 12 mol of carbon, 22 hydrogen 11 oxygen?
    My ratio would be 5/12 = 0.417
    I use the ratio 0.417 and multiply the mol? and solve for grams?
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  9. #8  
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    Quote Originally Posted by Lightz
    1 mol of sucrose is roughly 342 grams
    Wait in one mol of sucrose, there are 12 mol of carbon, 22 hydrogen 11 oxygen?
    My ratio would be 5/12 = 0.417
    I use the ratio 0.417 and multiply the mol? and solve for grams?
    1 mol sucrose (342g) =
    12 mol carbon (144g) + 22 mol hydrogen (22g) + 11 mol oxygen (176g)

    for 5 mol carbon (being 60g) - ratio would be 5/12 = 0.417
    (therefore 5 mol carbon would be in 5/12 (0.417) mol sucrose)

    multiply mols by ratio, and solve for grams ...
    (even simpler - multiply grams by ratio ...)

    looks good ...

    repeat for 2 mol carbon ... etc ...
    Nature abhors perfection; cats abhor a vacuum.

    "I don't know; I'm making it up as I go ..." Dr H Jones (Jr).
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