When a 3.22 g sample of an unknown hydrate of sodium sulfate, na2so4 ⋅ h2o (s), is heated, h2o (molar mass 18 g) is driven off. The mass of the anhydrous na2so4 (s) (molar mass 142 g) that remains is 1.42 g. The value of x in the hydrate is?

Question

Conor Juarez

Chemistry

5 April, 08:11

When a 3.22 g sample of an unknown hydrate of sodium sulfate, na2so4 ⋅ h2o (s), is heated, h2o (molar mass 18 g) is driven off. The mass of the anhydrous na2so4 (s) (molar mass 142 g) that remains is 1.42 g. The value of x in the hydrate is?

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Answers (1)

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Eliana Gordon · Answer 1

The value of X is 10 hence the formula of unknown hydrate sodium sulfate is NaSO4.10 H20

calculation

step 1:find the moles of NaSO4 and the moles of H2O

moles = mass/molar mass

moles of Na2SO4=1.42:142=0.01 moles

moles of H20 = mass of H2O/molar mass of H2O

mass of H2O = 3.22-1.42=1.8g

mole of H2O is therefore 1.8:18=0.1 moles

step 2: find the mole ratio by dividing each mole by smallest number of mole (0.01)

that is Na2So4 = 0.01/0.01 = 1

H2O = 0.1/0.01=10