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ICSE Class 10 Chemistry Question 28 of 72

Mole Concept & Stoichiometry Miscellaneous Exercises — Question 28

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Question 27

If a crop of wheat removes 20 kg of nitrogen per hectare of soil, what mass of the fertilizer, calcium nitrate Ca(NO3)2 would be required to replace the nitrogen in a 10 hectare field ?

Answer

Molecular mass of Ca(NO3)2

= 40 + [2(14) + 6(16)]
= 40 + 28 + 96
= 164 g

Mass of N2 in Ca(NO3)2 = 28 g

In 1 hectare of soil, 20 kg of N2 is removed

∴ In 10 hectare field N2 removed is 20 x 10 = 200 kg

28 g N2 is present in 164 g of Ca(NO3)2

So, 200 kg or 200,000 g of N2 is present in 16428\dfrac{164}{28} x 200,000

= 1171428 g = 1171.4 kg