<p>There is a question in the book that completly stumps me and i have a question like it on the test on Monday but I don't have class tommorow.</p>
<p>Here it goes:</p>
<p>The natural abundance of the 2 stable isotopes of hydrogen (hydrogen and deuterium) adre 1, 1 (1 over 1)H:99.985% and 2,1 H: .015%. Assume that water exists as either H20 or D20. Calculate the number of D20 molecules in 300mL of water. (Density= 1.00g/mL)</p>
<p>Any help is greatly appreciated!</p>
<p>This is a complete stab in the dark since I haven't had chem in a while:</p>
<p>300 mL. Convert to grams, then to mols H20. Use Na (Avagadro's number) to convert to number of molecules (should be a pretty big number). Right now you have the number of molecules of H20. Multiply by 2 to get molecules of H (2 Hs in H20). Then multiply .015% by number of Hs.</p>
<p>I'm going to assume that's right until somebody points out why its wrong.</p>
<p>Sry I didn't crunch the numbers, I can't find my calculator ATM.</p>
<p>:)</p>
<p>The back of the book says the answer is 2.01e23. Im not sure why.</p>