An unknown compound was found to have a percent composition as follows 47.0% potassium, 14.5% carbon, and 38.5% oxygen. What is its empirical formula?

1 Answer
anor277
Jan 2, 2016

Potassium oxalate?

Explanation:

In 100 g of compound there are 47.0 g potassium, 14.5 g carbon, and 38.5 g oxygen. Why?

We divide thru by the atomic masses:

#K# #=# #(47.0*g)/(39.1*g*mol^(-1))# #=# #1.20#.

#C# #=# #(14.5*g)/(12.0*g*mol^(-1))# #=# #1.21#.

#O# #=# #(38.5*g)/(16.0*g*mol^(-1))# #=# #2.4#.

Now if we divide thru by the lowest ratio, we get #K_nC_mO_o# #=# #KCO_2# as the empirical formula.

You have likely got the dipotassium salt of oxalic acid, #HOC(=O)C(=O)OH#, which has precisely this empirical formula. I take it you are an undergraduate?

Related questions
See all questions in Percent Composition
Impact of this question
6327 views around the world
You can reuse this answer
Creative Commons License