Question

Find the total percentage of oxygen in magnesium nitrate crystals : Mg(NO3)2. 6H2O
[O = 16, N = 14, H = 1, Mg = 24]

August 4, 2024

Answer

Molecular weight of magnesium nitrate Mg(NO₃)₂. 6H₂O

= 24 + 2[14 + 3(16)] + 6[2(1) + 16]

= 24 + 2[14 + 48] + 6(18)

= 24 + 2(62) + 6(18)

= 24 + 124 + 108

= 256 g

Mass of oxygen in Mg(NO₃)₂. 6H₂O

= 6(16) + 6(16)

= 96 + 96 = 192

256 g of magnesium nitrate crystals contains 192 g of oxygen

∴ 100 g of magnesium nitrate crystals contains

= $192\over 256$ × 100 = 75 %

Hence, total percentage of Oxygen in magnesium nitrate crystals is 75%

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