Finding the value of x...(chemistry)?

Question

Washing soda is a hydrate, which means that a certain number of water molecules are included in the solid structure. Its formula can be written as Na2CO3 X xH2O, where x is the number of moles of H2O per mole of Na2CO3. When a 2.558-g sample of washing soda is heated at 125 degrees C, all the water of hydration is lost, leaving 0.0948 g of Na2CO3. What is the value of x?

I greatly appreciate your time and help

10 points

Answer 1

You sure it's 0.0948 g, not 0.948? Because if it's 0.948 g then the answer is 10. Not sure though

Answer 2

The mass of Na2CO3 must be 0.948 g and NOT 0.0948 g.

Water lost = 2.558 g - 0.948 g = 1.610 g H2O

moles H2O = 1.610 g / 18.0 g/mole = 0.0894 moles H2O

moles Na2CO3 = 0.948 g / 106 g/mole = 0.00894 moles Na2CO3

moles H2O / moles Na2CO3 = 0.0894 / 0.00894 = 10

Henc ethe formula is Na2CO3 x 10 H2O.