Question

if a commercial fertiliser weighing 2.5 kg had the series 12–4–32 written on its label, what mass of nitrogen, phosphorus and potassium would you expect it to contain

Answer 1

The fertilizer has 0.3kg of nitrogen, 0.1kg of phosphorus and 0.8kg of potassium.

Step-by-step explanation:

The series 12-4-32 indicates the percentage of each element in the fertilizer. So, in this case, there are 12% of nitrogen, 4% of phosphorus and 32% of potassium, and the rest will be oxygen.

knowing that the 100% of the fertilizer is equivalent to 2.5kg, we can calculate the mass of each element using a mathematical rule of three:

• Mass of Nitrogen:

`\begin{gathered} 100\%-2.5kg \\ 12\%-x=(12\%*2.5kg)/(100\%) \\ x=0.3kg \end{gathered}`

• Mass of Phosphorus:

`\begin{gathered} 100\%-2.5kg \\ 4\%-x=(4\%*2.5kg)/(100\%) \\ x=0.1kg \end{gathered}`

• Mass of potassium:

`\begin{gathered} 100\%-2.5kg \\ 32\%-x=(32\%*2.5kg)/(100\%) \\ x=0.8kg \end{gathered}`

So, the fertilizer has 0.3kg of nitrogen, 0.1kg of phosphorus and 0.8kg of potassium.