Answer:
THE VALUE OF X IS 7 AND THE FORMULA OF THE HYDRATED SALT IS KAl(SO4)2.7H20
Explanation:
1. write out the varibales given in thequestion:
Mass of the hydrated salt = 4.74 g
Mass of water lost = 2.16 g
Formula of the hydrated salt = KAl(SO4)2. XH20
2. calculate the molar mass of the salt and that of water of crystallization:
Molar mass of anhydrous salt = ( K = 39, Al = 27, S = 32, 0=16)
= ( 39 + 27 + 32*2 + 16 * 8
= (39 + 27 + 64 + 128)
= 258 g/mol
Molar mass of water = 18 g/mol
3. Use this expression to calculate X:
The expression,
XH20 / molar mass of anhydrous salt = Mass of water lost / Mass of hydrated salt.
X = molar mass of anhydrous salt * mass of water lost / mass of anhydrous salt * H20
where XH20 is the molar mass of water of crystallization, is used to calculate the value of X.
4. Solve for X:
So therefore:
X = 258 * 2.16 / 4.74 * 18
X = 557.28/ 85.32
X = 6.53
X is approximately 7.
The value of X is 7 and the formula pf the hydrated salt is KAl(SO4)2.7H20
