Rounding in Mole Ratios for Empirical Formulas

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Christine Chen 1H
Posts: 64
Joined: Fri Sep 28, 2018 12:18 am

Rounding in Mole Ratios for Empirical Formulas

Postby Christine Chen 1H » Thu Oct 04, 2018 11:37 pm

When multiplying by an integer to get a whole number for the mole ratio in an empirical formula, do you round the other numbers before multiplying them also? Or do you keep the unrounded number and multiply it by the same integer?

Ex. If the ratio for C is 1, H is 9.77, and O is 5.56, you multiply 2 by 5.56 to get 11. Do you round 9.77 to 10 and then multiply by 2? or do you multiply 9.77 by 2?

Ethan Breaux 2F
Posts: 63
Joined: Sat Sep 29, 2018 12:16 am

Re: Rounding in Mole Ratios for Empirical Formulas

Postby Ethan Breaux 2F » Thu Oct 04, 2018 11:53 pm

I would instead treat 9.77 as 9.75 and multiply the ratio by 4 so you end up with C 5 : H 39 : O 22 (its more accurate this way). Just look to see if decimals can be rounded to .25 .5 or .75 cuz those are easy numbers to work with.

Madeera_Mian_3B
Posts: 30
Joined: Fri Sep 28, 2018 12:24 am

Re: Rounding in Mole Ratios for Empirical Formulas

Postby Madeera_Mian_3B » Fri Oct 05, 2018 12:23 am

I agree with Ethan, making the decimal points easy to work with can make the multiplication easier. I usually find a number that satisfies most of the ratios and try to round off near the end.


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