Final answer:
The balanced chemical equation for sodium reacting with oxygen is
4Na(s) + O2(g) → 2Na2O(s).
The balanced equation for aluminium reacting with dilute hydrochloric acid is
2Al(s) + 6HCl(aq) → 2AlCl3(aq) + 3H2(g).
Step-by-step explanation:
To balance the equations for the reactions given in the question, we need to ensure that the number of atoms of each element is the same on both sides of the equation. Let's write the balanced equations for each reaction:
Sodium reacting with oxygen
4Na(s) + O2(g) → 2Na2O(s)
Aluminium reacting with dilute hydrochloric acid
2Al(s) + 6HCl(aq) → 2AlCl3(aq) + 3H2(g)
In the first reaction, sodium (Na) reacts with oxygen (O2) to form sodium oxide (Na2O). We balance this reaction by placing a coefficient of 4 in front of Na and a coefficient of 2 in front of Na2O.
In the second reaction, aluminium (Al) reacts with hydrochloric acid (HCl) to form aluminum chloride (AlCl3) and hydrogen gas (H2).
We start by balancing aluminum with a coefficient of 2 in front of Al and AlCl3, then balance chlorine by placing a coefficient of 6 in front of HCl, and finally balance hydrogen by placing a coefficient of 3 in front of H2.