LoserMe asked in Science & MathematicsChemistry · 7 years ago

# in 380 mLs of 0.109 M NaClO4, how many atoms of oxygen?

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• 7 years ago

Alright. You have a 0.109 M solution of NaClO4 - so there are 0.109 moles of NaClO4 in 1 L. With 380 mLs you can find the number of moles of that molecule.

(0.109 moles of NaClO4 / 1 L) * 380 mL * (1 L / 1000 mL) = 0.0414 moles of NaClO4

[Notice mL and L cancel out and leave you with just moles of NaClO4.]

In one mole of NaClO4, there are 4 oxygen atoms. In a sense, this is the same as saying in 1 mole of NaClO4 there is 1 mole of Na, 1 mole of Cl, and 4 moles of O.

0.0414 moles NaClO4 * (4 moles Oxygen / 1 mole NaClO4) = 0.166 moles of Oxygen.

[Notice "moles of NaClO4" cancel out and leave you with moles of oxygen.]

1 mole of a substance contains an Avogadros number of atoms, or 6.022 x 10^23 atoms.

So you get: 0.166 moles of oxygen * (6.022 x 10^23 oxygen atoms / 1 mole of oxygen) =

10.0 x 10^22 atoms of oxygen.

[Again, notice how moles of oxygen cancel out and leaves you with atoms of oxygen. Seriously, the vast majority of chemistry is just knowing how to properly set up equations so that your units cancel out correctly (dimensional analysis).]