A 140.5 g sample of niso4•xh2o was heated until no further mass decrease was noted. The remaining sample was assumed to be anhydrous niso4 with a mass of 77.5 g. First determine the moles of anhydrous niso4 and moles of h2o lost. What is the mole ratio of niso4 to water?

Question

Chemistry

Elena Franco

5 January, 13:18

A 140.5 g sample of niso4•xh2o was heated until no further mass decrease was noted. The remaining sample was assumed to be anhydrous niso4 with a mass of 77.5 g. First determine the moles of anhydrous niso4 and moles of h2o lost. What is the mole ratio of niso4 to water?

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Bria · Answer 1

moles of anhydrous nickel (II) sulfate salt = 0.908 mole

moles of water = 63/18 = 3.5 moles

The mole ratio of Nickel (II) Sulfate to Water = 1 : 4

Explanation:

mass of Nickel (II) sulfate hydrate = 140.5 grams

mass of Nickel (II) sulfate salt. = 77.5 grams

mass of water present in the hydrated Nickel salt can be calculated as : Mass of hydrated Nickel salt-mass of anhydrous salt

Therefore, mass of water = (140.5 - 77.5) = 63 grams

The moles of a substance is calculated as mass of substance/molar mass of substance

molar mass of water = 18 (Atomic mass of H=1*2=2g, O=16; 2+16=18g)

Thus moles of water = 63/18 = 3.5 moles

moles of Nickel (II) sulfate salt. = 140.5/154.69 (Molar mass of Nickel (II) sulfate is 154.75 i. e Ni = 58.69 + S = 32 + 0 = (16*4) = 64, Sum of atomic masses = 154.69

moles of anhydrous Nickel (II) sulfate salt = 0.908 mole

The mole ratio of Nickel (II) Sulfate to Water = 1 : 4