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)Orarr Na_(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_(3)-=X xx18` grams of water
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 `=(6.29)/(3.71)xx106`
= 180 grams
18 grams of water = 1 mole
180 grams of water = ?
Value of `X=(180)/(18)=10`