# chemistry need help

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Determine the number of moles of each specified atom or ion in the given samples of the following compounds.( Hint: the formula tells you how many atoms or ions are in each molecule of formula unit.)

a. O atom in 3.161x10^21 molecules of CO2
b. C atom in 3.161x10^21 molecules of CO2

c. O atom in 2.2222x10^24 molecules of CO2
d. K^+ ions in 5.324 *10^16 formula units of KNO2
e. CL^ - ions in 1.000 x 1o^14 formula units of MgCl2
f. N atoms in 2.000 * 10^14 formula units of Ca (NO3)2
g. O atoms in 4.999 x 10^25 formula units of Mg3(PO4)2

• chemistry need help - ,

There are 6.02 x 10^23 molecules in a mole of molecules or atoms in a mole of atoms. Here is how you do the first one.
3.161 x 10^21 molecules CO2 x (1 mole CO2 molecules/6.02 x 10^23 molecules CO2) x (2 atoms O/1 molecule CO2) = ?? moles O atoms in 3.161 x 10^23 molecules CO2.
The others are done the same way. Note the use of the factors. They all work this way, even with different problems (of course the factors are different for different kinds of problems).