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# chem, calculate empirical formula watch

1. For some reason, I can't do this question. I can usually do % by mass composition things fine, but this one wont work for me. I'm probably just being retarded, but help?

Calculate the empirical formula of X which has the following composition by mass -

K - 32%
Cr - 21.3%
F - 46.7%

RMM

K - 39
Cr - 52
F 19
2. i get CrK2F6
3. 32/39 = 0.820512820512820512820512820512 82
21.3/52 = 0.409615384615384615384615384615 38
46.7/19 = 2.457894736842105263157894736842 1
--------------
1/ 0.409615384615384615384615384615 38 = 2.441314553990610328638497652584 5
--------------
2.441314553990610328638497652584 5 * 0.820512820512820512820512820512 82 = 2
2.441314553990610328638497652584 5 * 0.409615384615384615384615384615 38 = 1
2.441314553990610328638497652584 5 * 2.457894736842105263157894736842 1 = 6
--------------
K2CrF6
4. agreed
5. (Original post by aMb)
32/39 = 0.820512820512820512820512820512 82
21.3/52 = 0.409615384615384615384615384615 38
46.7/19 = 2.457894736842105263157894736842 1
--------------
1/ 0.409615384615384615384615384615 38 = 2.441314553990610328638497652584 5
--------------
2.441314553990610328638497652584 5 * 0.820512820512820512820512820512 82 = 2
2.441314553990610328638497652584 5 * 0.409615384615384615384615384615 38 = 1
2.441314553990610328638497652584 5 * 2.457894736842105263157894736842 1 = 6
--------------
K2CrF6

hw the hell did you guys do this?
isnt the empirical formula done by ratios?
umm..i think i got it......but i dnt remember using percentages, they gaves us teh mass of each and u had to dvide by molecular mass, hw do u use the percentage to get the ratios?
6. Use just use the percentages as masses. It works out the same
7. thanks man, i was dyin a bit there

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