Question

Washing soda, a compound used to prepare hard water for washing laundry, 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⋅χH2O 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∘C all the water of hydration is lost, leaving 0. 948 g of Na2CO3.What is the value of x?

Answer 1

X = 10

Step-by-step explanation:

First, we need to calculate the moles of Na₂CO₃ in the 0.948g. Then, the moles of water based on the difference of masses. X will be the ratio of moles of water and moles of sodium carbonate.

Moles Na₂CO₃ (Molar mass: 105.99g/mol):

0.948g * (1mol / 105.99g) = 8.944x10⁻³ moles

Moles H₂O (Molar mass: 18.02g/mol):

2.558g - 0.948g = 1.61g of water

1.61g * (1mol / 18.02g) =0.08935 moles

The ratio, X, is:

0.08935mol / 8.944x10⁻³ moles

X = 10