Balance the chemical equation Li + HNO3 → LiNO3 + H2

What you are balancing in this reaction

Lithium metal reacts with nitric acid to form the salt lithium nitrate and hydrogen gas. Your job is to choose whole-number coefficients so each element has the same number of atoms on both sides.

Treating $NO_3$ as a unit makes it faster

Because $NO_3$ stays together in $HNO_3$ and $LiNO_3$, you can balance the nitrate group as a single unit:

• Left side has 1 nitrate group ($HNO_3$).
• Right side has 1 nitrate group ($LiNO_3$). So nitrate is already balanced.

Balance lithium and hydrogen

Start with lithium:

• Left has 1 $Li$.
• Right has 1 $Li$ in $LiNO_3$. So lithium is also balanced at first.

Now check hydrogen:

• Left has 1 H in $HNO_3$.
• Right has 2 H in $H_2$. To make hydrogen even, put 2 in front of $HNO_3$: $$Li + 2HNO_3 \rightarrow LiNO_3 + H_2$$ Now hydrogen balances (2 H on both sides), but nitrate and lithium no longer do.

Adjust coefficients to finish

With $2HNO_3$, you have 2 nitrate groups on the left, so put 2 in front of $LiNO_3$: $$Li + 2HNO_3 \rightarrow 2LiNO_3 + H_2$$ Now you have 2 lithium atoms on the right, so put 2 in front of $Li$: $$2Li + 2HNO_3 \rightarrow 2LiNO_3 + H_2$$

Quick check of atom counts

• $Li$: 2 left, 2 right
• $H$: 2 left, 2 right
• $N$: 2 left, 2 right
• $O$: 6 left, 6 right So the equation is balanced.