Question

na₂s(aq) + cu(no₃)₂(aq) → nano₃(aq) + cus(s)
express your answers as integers separated by commas.

Explanation:

Step1: Balance sodium atoms

There are 2 sodium atoms on the left - hand side in $Na_2S$. So we need 2 moles of $NaNO_3$ on the right - hand side to balance sodium.
$Na_2S(aq)+Cu(NO_3)_2(aq)
ightarrow 2NaNO_3(aq)+CuS(s)$

Step2: Check other elements

After putting 2 in front of $NaNO_3$, copper, sulfur, nitrogen and oxygen atoms are also balanced.

Answer:

1,1,2,1