Chemistry thing?

Question

can you tell me what you got from this...i just don't know how to multiply avogrado's number like in this: How many grams of NaOH is produced from 1.20x10^2 grams of Na*2O? How many grams of Na*2O are required to produce 1.60x10^2 grams of NaOH? How many atoms of NaOH are made?

Na*2O+H*2O->2 NaOH

Answer 1

I made a picture in paint of the factor label methods you need to use to solve this. http://img.photobucket.com/albums/v420/noalei/chemhelp.jpg

But also, I'll try to give you, in words, the same information.

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How many grams of NaOH is produced from 1.20x10^2 grams of Na*2O?

1.2x10^2g Na*2O x (1 mole Na*2O / 61.979g Na*2O) x (2 mole NaOH / 1 mole Na*2O) x (39.997g NaOH / 1 mole Na OH) = 154.89g NaOH
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How many grams of Na*2O are required to produce 1.60x10^2 grams of NaOH?

1.60x10^2g NaOH x (1 mole NaOH / 39.997g NaOH) x (1 mole Na*2O / 2 mole NaOH) x (61.979g Na*2O / 1 mole Na*2O) = 123.967g Na*2O
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How many atoms of NaOH are made?

By the way, as you probably know, you have to take the number you started with down from the second problem (1.60x10^2 grams of NaOH).

1.60x10^2g NaOH x (1 mole NaOH / 39.997g NaOH) x (6.02x10^23 atoms NaOH / 1 mole NaOH) = 2.408x10^24 atoms NaOH
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I will be on Seaelventears on AIM messenger and [e-mail] on MSN messenger for about 10-15 more minutes if you want to get on and ask any other questions. Good luck!

Answer 2

You only need Avogadro's number at the very end.

The first parts are normal stoichiometry. Convert the grams given to moles by using the molecular mass of each compound. Use the molar ratio to determine the grams of Na2O required.

For the last step, take the moles of NaOH you calculated above and multiply that by Avo's number. That will give you the molecules of NaOH (not atoms as you wrote).