Empirical Formula with fraction coefficient

[RSD2014]

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A compound composed of C, H, O. 71.98% C, 6.71%H, 21.3%O. What is the Empirical Formula of the compound?


I basically converted them to mole and divide each by the lowest mole.
it comes out. 4.5 C : 5 H, 1 O

I am thinking, multiply the whole thing by 2, to make the coefficient whole#. To get C9 H10 O2. (My gut tells me this is the correct way).

However, how do we know to multiply it by 2 instead of rounding 4.5 --> 5? It would give C5 H5 O.

What if the coefficient is 7.8 C, 5 H, 1 O?
would we round it to C8 H5 O?
or multiply it by 5 to get C39 H 25 O5?

any feedback is appreciated.

 

[chromosome21]

First que. Yes, you should multiply to make the coefficient whole #. It's mentioned in barron's AP chem.

Second que. Not sure. I'd say round off, but not sure.

I dont' think dat would ask such type of a question.

When are you taking your exam?

 

[UndergradGuy7]

A compound composed of C, H, O. 71.98% C, 6.71%H, 21.3%O. What is the Empirical Formula of the compound?


I basically converted them to mole and divide each by the lowest mole.
it comes out. 4.5 C : 5 H, 1 O

I am thinking, multiply the whole thing by 2, to make the coefficient whole#. To get C9 H10 O2. (My gut tells me this is the correct way).

However, how do we know to multiply it by 2 instead of rounding 4.5 --> 5? It would give C5 H5 O.

What if the coefficient is 7.8 C, 5 H, 1 O?
would we round it to C8 H5 O?
or multiply it by 5 to get C39 H 25 O5?

any feedback is appreciated.

4.5 is not close to 4 or 5, its in the middle. Rounding it to 5 would be a big error. Multiplying by 2 would give a perfect whole number.

Don't think the dat would have 7.8. They are mostly easy calculations.

 

[DoCt0rPeTe]

4.5 is not close to 4 or 5, its in the middle. Rounding it to 5 would be a big error. Multiplying by 2 would give a perfect whole number.

Don't think the dat would have 7.8. They are mostly easy calculations.

+1