Question

A 90.00 g sample of Na, CO *xH, O is heated until all of the water is driven

off, forming 32.28 g of the anhydrous salt, Na, Coz. What is the percent by
mass of H,O in the hydrated compound, Na CO, *xH,O?*

Answer 1

The percent by mass of H₂O in the hydrated compound, Na₂CO₃.xH₂O = 64.13%

Further explanation

Given

90 g sample Na₂CO₃.xH₂O

32.28 g Na₂CO₃

Required

The percent by mass of H₂O

Solution

mass of H₂O = mass of sample - mass of the anhydrous salt, Na₂CO₃

`\tt mass~H_2O=90-32.28=57.72~g`

The percent by mass :

`\tt \%mass~H_2O=(mass~H_2O)/(mass~sample)* 100\%\\\\\%mass~H_2O=(57.72)/(90)* 100\%\\\\\%mass~H_2O=64.13\%`