Question

if a crop of wheat removes 30 kg of nitrogen per hectare of soil ,what mass of the fertiliser calcium nitrate would be required to replace the nitrogen of a 5 hectare land(at wt: N =14, o =16 ,Ca =40)

Answer 1

Molar mass of Ca(NO3)2 is 164 g. Mass of N in 1 mole Ca(NO3)2 is 28 g. That is 17.1 % of total mass.

Total required mass of nitrogen = 30*5 kg=150 kg = 150000g. 1kg = (1000g)

17.1% Mass of Ca(NO3)2 = 150000g
Mass of Ca(NO3)2 = 150000*(100/17.1) g = 877192.982g. = 877.192 kg = 877.2 kg.


So Ca(NO3)2 is required 877.2 kg.

Answer 2

Explanation:

Given,

1 hectare -----> 30kg of N2 (nitrogen).

5 hectare-----> 5*30= 150Kg of N2. (150*1000=150000g)

Calcium Nitrate formula is Ca(NO3)2

So, molecular mass of calcium Nitrate is 164g.

In this Nitrogen (N2) mass is 28g.

Therefore, 28g of nitrogen requires 164g of Calcium Nitrate.

150000g of nitrogen require ( 164*150000 ) / 28 = 8785771.4g

In kg, 8785771.4/1000 = 878.57kg

Nearest kg would be after rounding off 879 kg. of Calcium Nitrate.

Hope this gives much easier and patent solution to your asked question. :)