percent composition

[TimeforDAT]

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Bleaching agent is analyzed to give 28% Ca, 22% O, and 50% Cl by mass. Find the empirical formula. So based off 100 grams, we know that it will have 28 grams of Ca, 22 grams of O, and 50 grams of Cl.

Now we find moles.

Ca: 28/40

O: 22/16

Cl: 50/35

my question is, why for oxygen you divide by 16, aren't you supposed to divide by the molar mass of the elemental form, in which case oxygen would be oxygen gas (O2).

Same goes for Cl, why isn't the molar mass 70 g/mol?

 

[jackbauer!]

Bleaching agent is analyzed to give 28% Ca, 22% O, and 50% Cl by mass. Find the empirical formula. So based off 100 grams, we know that it will have 28 grams of Ca, 22 grams of O, and 50 grams of Cl.

Now we find moles.

Ca: 28/40

O: 22/16

Cl: 50/35

my question is, why for oxygen you divide by 16, aren't you supposed to divide by the molar mass of the elemental form, in which case oxygen would be oxygen gas (O2).

Same goes for Cl, why isn't the molar mass 70 g/mol?

b/c O and Cl are not in their elemental form, they are part of a compound.

jb!🙂

 

[TimeforDAT]

oh haha..thanks.👍