Question

ammonium phosphate ((nh4)3 po4) is an important ingredient in many solid fertilizers. it can be made by reacting aqueous phosphoric acid (h3 po4) with liquid ammonia. calculate the moles of ammonia needed to produce 0.10 mol of ammonium phosphate. be sure your answer has a unit symbol, if necessary, and round it to the correct number of significant digits.

Explanation:

Step1: Write the balanced chemical equation

$$\ce{H3PO4 + 3NH3 ightarrow(NH4)3PO4}$$

From the equation, the mole ratio of $\ce{NH3}$ to $\ce{(NH4)3PO4}$ is $3:1$.

Step2: Calculate the moles of ammonia

Let $n(\ce{NH3})$ be the moles of ammonia and $n(\ce{(NH4)3PO4}) = 0.10\space mol$.
Using the mole ratio $\frac{n(\ce{NH3})}{n(\ce{(NH4)3PO4})}=\frac{3}{1}$, we can solve for $n(\ce{NH3})$:
$$n(\ce{NH3})=3\times n(\ce{(NH4)3PO4})$$
$$n(\ce{NH3}) = 3\times0.10\space mol$$

Answer:

$0.30\space mol$