Fertilisers：練習題

A student reads a bag of fertiliser and sees the label NPK. Which three elements essential for plant growth do these letters represent?

What is the correct chemical formula for ammonium nitrate, a widely used nitrogenous fertiliser?

A bag of NPK fertiliser is labelled 15-10-12. These numbers represent the percentage by mass of N, \(P_2O_5\), and \(K_2O\) respectively.
How many grams of nitrogen are present in a 20kg bag of this fertiliser?

Why is nitrogen included in most synthetic fertilisers?

A farmer adds an ammonium salt fertiliser to a field. Shortly after, she adds slaked lime (calcium hydroxide) to reduce the acidity of the soil.
What is the likely consequence of this action?

State the names of the three elements provided by NPK fertilisers to improve plant growth.

Calculate the percentage by mass of nitrogen in ammonium sulfate, \((NH_4)_2SO_4\).
[Relative atomic masses, \(A_r\): \(N = 14\), \(H = 1\), \(S = 32\), \(O = 16\)]

Compare the roles of phosphorus and potassium in the context of NPK fertilisers and plant development.

NPK fertilisers are commonly used by farmers to improve the yield of crops.
(a) Identify the three elements provided by NPK fertilisers.
(b) Explain why plants require nitrogen and phosphorus for healthy growth.

Ammonium sulfate, \( (\text{NH}_4)_2\text{SO}_4 \), is a nitrogenous fertiliser.
(a) State the word equation for the production of ammonium sulfate from ammonia and sulfuric acid.
(b) Calculate the percentage by mass of nitrogen in ammonium sulfate.
[Relative atomic masses: \( \text{N}=14, \text{H}=1, \text{S}=32, \text{O}=16 \)]