Question

If a crop of wheat removes 20 kg of nitrogen per hectare of soil, what mass in kg. of the fertilizer calcium nitrate would be required to replace the nitrogen in a 10 hectare field

August 4, 2024

Answer

Molecular weight of Ca(NO₃)₂

= 40 + 2[14 + 3(16)]

= 40 + 2[14 + 48]

= 40 + 2(62)

= 40 + 124 = 164 g

Total nitrogen that has to be replaced in 10 hectares of land

= 20 × 10 = 200 kg

28 g of N is present in 164 kg of calcium nitrate

∴ 200 kg of N is present in = $164\over28$ × 200

= 1171 kg

Hence, 1171 kg of fertilizer will be required

💡 Some Related Questions

Copper [II] sulphate soln. reacts with sodium hydroxide soln. to form copper hydroxide according to the equation :
2NaOH + CuSO4 ⟶ Na2SO4 + Cu(OH)2↓
What mass of copper hydroxide is precipitated by using 200 g of sodium hydroxide.
[H = 1, O = 16, Na = 23, S = 32, Cu = 64]

Aluminium carbide reacts with water according to the following equation :
Al4C3 + 12H2O ⟶ 4Al(OH)3 + 3CH4
(i) State what mass of aluminium hydroxide is formed from 12 g. of aluminium carbide.
(ii) State the volume of methane at s.t.p. obtained from 12 g of aluminium carbide.
[relative molecular weight of Al4Cl3] = 144 ; Al(OH)3 = 78

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From the equation :
(NH₄)₂Cr₂O₇ ⟶ N₂(g) + 4H₂O(g) + Cr₂O₃
Calculate:
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(NH₄)₂Cr₂O₇ is heated.
(ii) the quantity in moles of N₂ formed.
(iii) the volume in litres or dm3 of N₂ evolved at s.t.p.
(iv) the mass in grams of Cr₂O₃ formed at the same time.
[H = 1, Cr = 52, N = 14]

KClO3 ${\overset{ MnO2 }{\longrightarrow}}$ 2KCl + 3O2
(i) Calculate the mass of KClO3 required to produce 6.72 lit of O2 at s.t.p.
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(ii) Calculate the number of moles of O2 in the above volume and also the number of molecules.

P + 5HNO3 [conc.] ⟶ H3PO4 + H2O + 5NO2.
If 9.3 g of phosphorous was used in the reaction, calculate :
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[H = 1, N = 14, P = 31, O = 16]

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Commercial NaOH weighing 30 g. has some NaCl in it. The mixture on dissolving in water and treatment with excess AgNO3 soln. formed a precipitate weighing 14.3 g. What is the percentage of NaCl in the commercial sample of NaOH.
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[Relative molecular mass of NaCl = 58 ; AgCl = 143]

From the equation : C + 2H2SO4 ⟶ CO2 + 2H2O + 2SO2
Calculate :
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A sample of ammonium nitrate when heated yields 8.96 litres of steam (measured at step.)
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