Question

How many grams of product are formed from 2.0 mol of N2 (g) and 8.0 mol of Mg(s)? Show all calculations leading to an answer. List 3 indicators of a chemical change.

Answer 1

Balanced chemical reaction happening here is:

3Mg(s) + N₂(g) → Mg₃N₂(s)        

 moles of product formed from each reactant:

2.0 mol of N2 (g) x 1 mol Mg₃N₂        = 2 mol Mg₃N₂

                                    1 mol N2

and

8.0 mol of Mg(s) x 1 mol Mg₃N₂         = 2.67 mol Mg₃N₂

                                 3 mol Mg

Since N2 is giving the least amount of product(Mg₃N₂) ie. 2 mol Mg₃N₂

N2 is the limiting reactant here and Mg is excess reactant.

Hence mole of product formed here is 2 mol Mg₃N₂    

molar mass of Mg₃N₂    

= 3 Mg + 2 N

= 101g/mol  

mass of product(Mg₃N₂) formed  

= moles x Molar mass

= 2 x 101

= 202g Mg₃N₂

202g of product are formed from 2.0 mol of N2(g) and 8.0 mol of Mg(s).

    The following are indicators of chemical changes:

Change in Temperature    

Change in Color

Formation of a Precipitate