<p>So I'm taking AP Chem this fall and I'm trying to complete this summer assignment. The problem is that I haven't taken Chemistry since last summer (a 22 day summer course) and I'm seriously confused on one of its most basic concepts! I swear if someone can explain the nature of this question, I can figure out the rest of these problems. Anyway, go ahead and laugh, as long as you help me out ; ). Here we go:</p>
<p>How many atoms of Carbon are present in 1.0 grams of CH4O. </p>
<p>I know the molar is 32.05 grams. So does that mean I do:</p>
<p>1.0 g CH4O x 1 mol CH4O x 6.022x10^23 atoms C = Answer?
.................. ~~~~~~~ .. ~~~~~~~~<br>
..................32.05 g CH4O .. 1 mol C</p>
<p>~ = div. sign
. = space </p>
<p>Anyway, aren't I missing a step? Shouldn't I take into account the relationship b/t the number of moles of the substance and the number of moles of the element? For example, if I were finding Hydrogen atoms instead, should I divide by 4 in the third fraction, instead of one? Yea, if that's not right, please feel free to ignore me. Thanks.</p>
<p>Here's how I would do it. (--- is the division sign)</p>
<h2>1.0g CH40</h2>
<p>32.05g/mol</p>
<p>Gives you mol.
mol X (6.02X10^23) gives you the number of carbon atoms.</p>
<p>If, say, you wanted the number of hydrogen atoms, then you would
(mol X (6.02X10^23)) X 4.</p>
<p>Hopefully that makes sense. I'm pretty sure that your way would work too.</p>
<p>Oh snap! Thanks man, you totally saved my life. I actually had the right answer for that problem, but only because it was a one-one ratio; I would have had it wrong if it were asking for Hydrogen. Phew. Thanks again.</p>
<p>Molar mass of CH4O = 32.05 g/mol</p>
<h1>of moles of CH4O = 1.0g / (32.05g/mol) = 0.03120 mol</h1>
<p>Because there is only one C in CH4O, </p>
<h1>of moles of C = 0.03120 mol * 1 = 0.03120 mol</h1>
<p>(if it were figuring out for hydrogen, you'd have go multiply it by 4)</p>
<p>Since the question is asking for the number of atoms,
you multiply 0.03120 mol by the avogadro's number.</p>
<p>0.03120 mol * 6.022 * 10^23 / mol = 1.87 * 10^22 atoms</p>
<p>But since the original question has 2 significant digits, the answer is
1.9 * 10^22 atoms.</p>
<p>=)</p>
<p>oops i guess i replied too late :P</p>
<p>Hey. the most important thing with conversions in chem is that you usually convert something to moles and then to something else. thing of moles as quantity. moles is really just a biggass number. covert to liters to moles then to grams or whatnot. you pass through moles. just remember to think moles is usually the center unit and just covert to moles (if possible) when in doubt.</p>
<p>(i repeat myself to make it stick! ;))</p>