Q3.141CP - Chemistry: Molecular Nature Of Matter And Change

Question

What mass % of ammonium sulfate, ammonium hydrogen phosphate, and potassium chloride would you use to prepare 10/10/10 plant fertilizer (see Problem 3.140)?

Step-by-Step Solution

Answer

The mass percentage are 47% (NH₄)₂SO₄, 18% (NH₄)₂HPO₄ and 16% KCl.

Step 1: Finding Moles of N, P and K

On finding the moles,

$$\begin{gathered} Moles of N=10 g N\times \frac{1 mol N}{14.01 g N}=0.71 mol N \\ Moles of P=10 g P_2{O}_3\times \frac{1 mol P_2{O}_5}{141.94 g P_2{O}_5}\times \frac{2 mol P}{1 mol P_2{O}_5}=0.14 mol P \\ Moles of K=10 g K_{2}O\times \frac{1 mol K_{2}O}{94.2 g K_{2}O}\times \frac{2 mol K}{1 mol K_{2}O}=0.21 mol K \end{gathered}$$

Step 2: Finding the mass

On finding the mass,

$$\begin{gathered} Mass of (N{H}_4{)}_{2}S{O}_4=0.71 mol N\times \frac{1 mol {\left(N{H}_4\right)}_{2}S{O}_4}{2 mol N}\times \frac{132.14 g {\left(N{H}_4\right)}_{2}S{O}_4}{1 mol{\left(N{H}_4\right)}_{2}S{O}_4}=47 g \\ Mass of (N{H}_4{)}_{2}HP{O}_4=0.14 mol P\times \frac{1 mol {\left(N{H}_4\right)}_{2}HP{O}_4}{1 mol P}\times \frac{132.06 {\left(N{H}_4\right)}_{2}HP{O}_4}{1 mol {\left(N{H}_4\right)}_{2}HP{O}_4}=18 g \\ Mass of KCl=0.21 mol K\times \frac{1 mol KCl}{1 mol K}\times \frac{74.55 g KCl}{1 mol KCl}=16 g \end{gathered}$$