posted by Jaz .
Find the number of moles.
a. 3.01*10^23 molecules H2O.
b.1.000*10^23 atoms C.
c. 5.5610 *10^22 ions Na^+.
There are 6.02 x 10^23 anythings in a mole. Substitute ions, molecules, atoms, loaves of bread, you name it, for anythings.
can you help me wih the first 2
No, but I'll do the first one for you.
You want moles. Notice that I multiply what you have at the beginning by a factor. The conversion factor converts molecules to moles. Guess what the factor is? The factor is (1 mol/6.02 x 10^23 anythings).
3.01 x 10^23 molecules H2O x (1 mole/6.02 x 10^23 molecules H2O)= 0.500 mole H2O.
Notice how the unit molecules H2O in the numerator cancels with the unit molecules H2O in the denominator (which gets rid of the unit we don't want) but the unit we want to keep (the one we want for the answer) is mole and that stays in the numerator.