What are some basic laboratory tests that can tell me the chemical formula of a compound?

Question

So my teacher has given us a piece of white-chalk-like substance, and we need to tell him what it is. We have measured the density, acidity, etc. How can I tell how many moles of stuff are present in it and ultimately what it is? What are some tables that I can use to determine its composition?

Answer 1

First, see if it dissolves in water. Do not use up all of it! make a 1g/l solution, or even less.

then do preliminary testing:
http://home.clara.net/rod.beavon/prelim.htm

get the ideas of how to test different unknown anions and cations from the following:

http://home.clara.net/rod.beavon/anions.htm
http://home.clara.net/rod.beavon/cations.htm

Good luck!

Answer 2

Knowing what the pH of the substance is can give you information about its composition. Does it dissolve in water? Does it dissolve in other solvents? Does it fizz when you add acid to it? In order to obtain the number of moles, you first need to figure out what the molecular formula for the compound is. Using that information and the weight you can figure the amount of moles.

Answer 3

You need to conduct salt tests. Carry out tests with different reagents and observe the evolved products.