Calculate and compare the mass of the reactants with the mass of the products for each equation.

a)2KClO3 (s) ==> 2KCl(s) + 3O2 (g)
b)4NH3(g) + 6NO(g) ==> 5N2(g) + 6H2O(g)
c)4K(s) + O2(g) ==> 2K2O(s)

Show that each balanced equation obeys the law of conservation of mass.

2 answers

Calculate molar masses and show that they add up on both sides. For example, the first one.
KClO3 is 122.549 and 2 moles would be
2 x 122.549 = 245.098.
On the right we have
2 x 74.551 = 149.102 for 2KCl
3 x 31.9988 = 95.9964
149.102+95.9964 = 245.098
so the product decomposes but we didn't lose anything. The second one is done the same way.
Good work