10 grams of a hydrated sodium carbonate, `Na_(2)CO_(3).xH_(2)O`, on strong heating loses a weight of 6.29 grams. Report the value of x. 

Explanation

Hydrated sodium carbonate loses water of hydration on strong heating.
`Na_(2)CO_(3).xH_(2)OrarrNa_(2)CO_(3)+xH_(2)O`
1 mole of `Na_(2)CO_(3)` = x moles of `H_(2)O`
106 grams of `Na_(2)CO_(4)` = x "x" 18 grams of water
weight loss = 6.29 gms hence weight of leftover `Na_(2)CO_(3)` = 3.71 gms
3.71 grams of `Na_(2)CO_(3)` = 6.29 grams of water
3.71 grams of `Na_(2)CO_(3)` is related to 106 grams
6.29 grams of water is related to ?
Weight of water in one formula unit sallt =`(6.29)/(3.71)xx106 = 180 grams`
18 grams of water = 1mole
180 grams of water = ?
value of x `=("Weight of water in are formula unit of salt")/("formula weight of water") = (180)/(18)`
The value of x in `Na_(2)CO_(3).xH_(2)O = 10`