I am in a chemistry class with a teacher who doesn't teach. he basically hands out assignments and expects us to know how to do them. i went to see a tutor but he hardly knew english which confused me even more.
basically i need to know how to solve molar mass problems. grams to mols. mols to atoms. that kind of thing. any help is appreciated. or web pages that i can be referred to. thanks!
2006-09-11 10:57:07 · 4 answers · asked by Cree 2 in Education & Reference ➔ Homework Help
Sure. a mole is mass of what you are weighing divided by the molecular mass of the compound. You can determine the molecular mass using the chemical formula and a periodic chart. To convert moles to atoms, you multiply the number of moles by avogadro's number. Avogadro's number is 6.022*10^23 molecules per mole. So lets use an example:
Lets say I have 1g of NaCl. The mass of one sodium atom is 22.99, the mass of a chlorine is 35.45. So since we have one of each per molecule...
Molecular mass = 22.99 + 35.45 = 58.44
Moles = mass/molecular mass = 1g/58.44 = 0.017 moles of NaCl
To find how many atoms that is... we multiply 0.017 moles by(6.022E23) molecules/moles. The moles cancel out and your left with molecules.
Molecules = 0.017(6.022E23) = 1.02E22 molecules.
*note: if you dont know what E means it means times ten raised to the power of the number after it.
Hope this helps. :)
2006-09-11 11:26:34 · answer #1 · answered by Anonymous · 0⤊ 0⤋
To convert grams to mols, divide by the molecular weight (found on the periodic table for every element). If you're dealling with molecules with numersous elements, you'll need to total each one up to get the total molecular weight of the molecule (for examples CO2 = 12 (for C) + 2 * 16 (for two oxygens) = 44 grams/mol). For 88 grams of CO2, you'll have 88/44=2 mols.
To convert to atoms, multiply by Avagrado's number (6*10^-23). So 2 mols = 2 * 6 * 10^-23 = 12*10^-23.
Hope that helps
2006-09-11 18:07:44 · answer #2 · answered by tsihilin 3 · 0⤊ 0⤋
You need to look up what's called Avogadro's Constant, L.
It's 6.0221415 Ã 10^23 mol-1.
Ye gods, I haven't studied this since 1982, the last time I studied chemistry. :-)
2006-09-11 18:08:09 · answer #3 · answered by fiat_knox 4 · 0⤊ 0⤋
The best thing to do is to ask another teacher how teaches that subject
2006-09-11 18:05:02 · answer #4 · answered by Briana DeShe' 2 · 0⤊ 0⤋