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Thread: Converting grams to molecules

  1. #1 Converting grams to molecules 
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    Hi, i am given a question that states;

    Convert 0.35g BaOH to molecules

    I worked it out and my answer is 1.36 * 10^21
    i would like to know if that answer is correct?
    And by chance, is there any way that i can have an estimation as to what range of values i should expect my answer to be?

    Any help would be greatly appreciated!!
    thank you!!!


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  3. #2  
    Moderator Moderator AlexP's Avatar
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    It's been a long time since I've done any of those conversions so I thought I'd give it a try. I got 1.365... x 10<sup>21</sup>, so it's the same if you don't round.

    You shouldn't be expecting a range of values that your answer could fall in, you should get one unique answer. The only way it should differ a little bit is by differences in rounding, as seen above.


    "There is a kind of lazy pleasure in useless and out-of-the-way erudition." -Jorge Luis Borges
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  4. #3 Re: Converting grams to molecules 
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    Quote Originally Posted by DesertRose
    Hi, i am given a question that states;

    Convert 0.35g BaOH to molecules

    I worked it out and my answer is 1.36 * 10^21
    i would like to know if that answer is correct?
    And by chance, is there any way that i can have an estimation as to what range of values i should expect my answer to be?

    Any help would be greatly appreciated!!
    thank you!!!
    Avogadro's number represents the number of atoms or molecules in the atomic mass of an element or compound expressed in grams. for example. 1.00794g of hydrogen contains about atoms of hydrogen.

    The answer I've gotten is the same as Alex's
    Wise men speak because they have something to say; Fools, because they have to say something.
    -Plato

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  5. #4  
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    I got the same answer as you but my teacher says to put our answers for any question to 2 dp....

    thanks soooo much for your assistance!!!!
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  6. #5  
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    In Chemistry 101 at the University, one of the early lessons is in proper use of significant digits. Always pay attention to them and never use the wrong number of significant digits. When working a problem with multiple steps never round off intermediate calculations on the calculator, especially if the answer to the previous problem is input to the current one (round off only the recorded answer).... It's a trap to catch you making round off errors and dropping significant digits.

    All this to say the correct answer is 1.4 * 10^21
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  7. #6  
    Moderator Moderator AlexP's Avatar
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    Good point. DesertRose, did you do sig figs right at the beginning of the course?
    "There is a kind of lazy pleasure in useless and out-of-the-way erudition." -Jorge Luis Borges
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  8. #7  
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    Thanks, i'll keep that in mind!!!

    "Good point. DesertRose, did you do sig figs right at the beginning of the course?"
    -No, i did not do sig figs right at the beginning. I did it a long time ago (2 or 3 years ago to be more precise)
    So our knowledge on how to do it is based on our ability to remember.

    Again, i would like to say thank you sooooo much to all of you!!!!!!!! :-D
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