What is the balanced chemical equation for the reaction NH3 + H2SO4 → (NH4)2SO4?

What you are balancing here

You need the same number of each type of atom on both sides of the arrow. In this reaction, sulfur and oxygen stay together as the sulfate ion $SO_4$, so it is easiest to treat $H_2SO_4$ and the $SO_4$ part of the product as a unit.

Match the sulfate first

There is 1 sulfur and 4 oxygens in $H_2SO_4$, and the product $(NH_4)_2SO_4$ also has 1 sulfur and 4 oxygens.

So, keep the coefficient of $H_2SO_4$ as 1 and the coefficient of $(NH_4)_2SO_4$ as 1.

Balance nitrogen and hydrogen with ammonia

The product $(NH_4)_2SO_4$ contains 2 nitrogen atoms (because there are two $NH_4$ groups). Each $NH_3$ has 1 nitrogen, so you need 2 $NH_3$:

$$2NH_3 + H_2SO_4 \rightarrow (NH_4)_2SO_4$$

Now check hydrogen:

• Left side: $2NH_3$ gives $6$ H, and $H_2SO_4$ gives $2$ H, total $8$ H
• Right side: $(NH_4)_2$ gives $2 \times 4 = 8$ H

Everything matches.

Quick atom check

• N: $2$ left, $2$ right
• H: $8$ left, $8$ right
• S: $1$ left, $1$ right
• O: $4$ left, $4$ right