Determine the number of moles of oxygen atoms in each of the following. 4.74 mol H2O2 2.03 mol N2O 2.20×10−2 mol H2CO3 25.1 mol CO2?

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4.74 mol H2O2

The moles of the entire molecule times the total number of atoms in one formula unit = moles of the atom

4.74 mol times 2 = the answer

Here's another example I just made up:

Calculate moles of oxygen atoms in 4.74 mol Fe(NO3)3

The point you must see is that there are nine oxygens. The formula unit is Fe(NO3)3 and there are three nitrate groups (the NO3) and each nitrate has three O, so 3 x 3 = 9

4.74 mol times 9 gives the answer (make sure to round off to three sig figs, the 9 does not play a role in SF)...Show more