Question

PLEASE HELP!!
What kind of compound is (NH4)2C2O4 -ammonium oxalate - and what's the rule to naming it??

Answer 1

NH4)2C2O4 is a compound which is ammonium oxalate
NH4 is ammonium
C2O4 is called oxalate

Answer 2

Oxalic acid is really the common name of ethandioic acid which looks like this: See, it's the only possible way to get two carboxylic acids on an ethane molecule. So if you deprotonate oxalic acid, you just get oxalate which is the anion left behind, and as you can see since there are 2 Hydrogen atoms that can leave, there will be 2 negative charges left behind so they are balanced by 2 Ammonium cations. The difference between Ammonia and Ammonium is simple if you can remember that thing that end in -ium are usually positive. For example, Calcium is usually Ca2+ follows this similar sort of idea. I'll draw their Lewis structures out so you can see the difference between Ammonia and Ammonium:

Answer 3

Whoops, small typo, "ethanedioic acid" not "ethandioic acid"