Respuesta :
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
The value of X in the potassium aluminum sulfate hydrate, KAl(SO₄)₂.XH₂O is 12
From the question given above, the following data were obtained:
Mass of KAl(SO₄)₂.XH₂O = 4.74 g
Mass of water = 2.16 g
Value of X =?
- Next, we shall determine the mass of KAl(SO₄)₂.
Mass of KAl(SO₄)₂.XH₂O = 4.74 g
Mass of H₂O = 2.16 g
Mass of KAl(SO₄)₂ = 4.74 – 2.16
Mass of KAl(SO₄)₂ = 2.58 g
- Finally, we shall determine the formula of the compound in order to obtain the value of X. This is illustrated below:
Molar mass of KAl(SO₄)₂ = 39 + 27 + 2[32 + (4×26)] = 258 g/mol
Molar mass of H₂O = (2×1) + 16 = 18 g/mol
Mass of KAl(SO₄)₂ = 2.58 g
Mass of H₂O = 2.16 g
Divide by their molar mass
KAl(SO₄)₂ = 2.58 / 258 = 0.01
H₂O = 2.16 / 18 = 0.12
Divide by the smallest
KAl(SO₄)₂ = 0.01 / 0.01 = 1
H₂O = 0.12 / 0.01 = 12
Thus, the formula of the compound is KAl(SO₄)₂.12H₂O
Comparing KAl(SO₄)₂.12H₂O with KAl(SO₄)₂.XH₂O, the value of X is 12
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