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Rounding in Mole Ratios for Empirical Formulas

Posted: Thu Oct 04, 2018 11:37 pm
by Christine Chen 1H
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?

Re: Rounding in Mole Ratios for Empirical Formulas

Posted: Thu Oct 04, 2018 11:53 pm
by Ethan Breaux 2F
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.

Re: Rounding in Mole Ratios for Empirical Formulas

Posted: Fri Oct 05, 2018 12:23 am
by Madeera_Mian_3B
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.