What are common mistakes students make with empirical forumlas?
I'll get this started, hopefully other contributors will add...
An empirical formula is the lowest whole number ratio of elements in a compound
NaCl - is a 1:1 ratio of sodium ions to chloride ions
CO - is a molecule that contains one atom of C and one atom of O
HO - is the empirical formula for hydrogen peroxide, note the formula of hydrogen peroxide is
- Sometimes students think that empirical formulas and molecular formulas are always the same - they can be different
- Empirical formulas apply to both ionic and molecular compounds
- The ratio used to determine an empirical formula is a mole:mole ratio (not a mass:mass)
Example of 3: water has a 2:1 ratio of hydrogen to oxygen, the mass ratio of hydrogen to oxygen is 1:8). If you are determining an empirical formula from experimental data, you must convert from grams of elements to moles. Here is a link for a video which will show you how to do this.
Hope this helps!