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ICSE Class 10 Chemistry Question 62 of 72

Mole Concept & Stoichiometry Miscellaneous Exercises — Question 62

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Question

Question 50(b-iii)

Find the total percentage of Magnesium in magnesium nitrate crystals, Mg(NO3)2.6H2O.

(Mg = 24, N = 14, 0 = 16 and H = 1)

Answer

Molecular weight of Mg(NO3)2.6H2O = 24 + 2[14 + 3(16)] + 6[2(1) + 16]
= 24 + 2[14 + 48] + 6[18]
= 24 + 2(62) + 108
= 24 + 124 + 108 = 256 g

256 g of magnesium nitrate crystals contains 24 g of magnesium

∴ 100 g of magnesium nitrate crystals will contain = 24256\dfrac{24}{256} x 100 = 9.375% = 9.38%

Hence, percentage of magnesium in magnesium nitrate crystals is 9.38%