Question

Anhydrous sodium sulfate, Na2SO4, absorbs water vapor and is converted to the decahydrate, Na2SO4⋅10H2O.

How much would the mass of 24.40 g  of anhydrous 

Na 2 SO 4 increase if converted completely to the decahydrate?

Answer 1

24.40 grams of Anhydrous sodium sulfate will absorb 30.946 grams of water. First, calculate the molar mass of Anhydrous sodium sulfate by looking up the molar mass of each element in it. Sodium = 22.989769 Sulfur = 32.065 Oxygen = 15.999 Sum the product of each element count by their molar mass 2 * 22.989769 + 32.065 + 4 * 15.999 = 142.0405 So 1 mole of Anhydrous sodium sulfate masses 142.0405 grams Calculate how many moles you have. 24.40 g / 142.0405 g/mole = 0.171782 mole Calculate the molar mass of H2O Hydrogen = 1.00794 2 * 1.00794 + 15.999 = 18.01488 Each mole of Anhydrous sodium sulfate can absorb 10 moles of H2O, so 0.171782 moles * 10 * 18.01488 g / mole = 30.946 grams