Question

What is the percent by mass of water in Na S04.10H20?

total mass of element in compound noch
Use %Element=--
molar mass of compound
X II

Answer 1

Percent by mass of water is 56%

Step-by-step explanation:

First of all calculate the mass of hydrated compound as,

Mass of Sodium = Na × 2 = 22.99 × 1 = 45.98 g

Mass of Sulfur = S × 1 = 32.06 × 1 = 32.06 g

Mass of Oxygen = O × 14 = 16 × 14 = 224 g

Mass of Hydrogen = H × 20 = 1.01 × 20 = 20.2 g

Mass of Na₂S0₄.10H₂O = 322.24 g

Secondly, calculate mass of water present in hydrated compound. For this one should look for the coefficient present before H₂O in molecular formula of hydrated compound. In this case the coefficient is 10, so the mass of water is...

Mass of water = 10 × 18.02

Mass of water = 180.2 g

Now, we will apply following formula to find percent of water in hydrated compound,

%H₂O = Mass of H₂O / Mass of Hydrated Compound × 100

Putting values,

%H₂O = 180.2 g / 322.24 g × 100

%H₂O = 55.92 % ≈ 56%