Hmm no. 4. Magnesium reacts with nitrogen gas to become Magnesium nitride. I have to show the word equation, chemical equation and the balanced equation.
First, I have to know the word equation. Magnesium is solid, Nitrogen is gas and the product, Magnesium nitride, is solid also. So if I construct it to a word equation, it will be like this.
Magnesium (s)+ Nitrogen (g)--> Magnesium nitride (s)
Hmm, I think I got this! For the chemical equation , Magnesium is Mg, Nitrogen is N2 because it is diatomic and the product will be Mg3N2. It is because Magnesium has a 2+ charge while Nitrogen has 3- then cross multiply.
Mg (s)+ N (g)--> Mg3N2 (s)
Now I just have to balance the equation. If I count the number of atoms in both sides, I'll have 1 of Magnesium and 2 of Nitrogen at the reactant side while 3 of Magnesium and 2 Nitrogen at the product side. So to balance this, I will add a coefficient 3 before the Magnesium in the reactant side.