Assuming complete dissociation, calculate the expected freezing point of a solution prepared by dissolving 6 00 g of Glauber's salt, Na2SO4.10H20 in 0.100 kg of H20 (kf for water = 1.86 K kg/mol)
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Answered by
109
The correct answer should be - 271.96 K.
The complete reaction will be according to the equation -
Na₂SO₄ → 2Na⁺ + SO₄
So, three particles have been formed after complete dissociation.
The molar mass of Na₂SO₄.10H₂O will be = 46 + 32 + 64 + (10 x 18) = 322
The weight of water Wa = 0.1 kg = 100 g
The weight of the solute (Glauber's salt) Wb = 6.0 g
Kf = 1.86 k kg. mol⁻¹
i (Vont Hof factor) = 3
According to the relation, DTf = kf / MB x 1WB/WA x 1000 x i
= 1.86 / 322 x 6.0 / 100 x 1000 x 3 = 1.039 K
So, the freezing point will be calculated as = 273 - 1.039 K = 271.96 K
The complete reaction will be according to the equation -
Na₂SO₄ → 2Na⁺ + SO₄
So, three particles have been formed after complete dissociation.
The molar mass of Na₂SO₄.10H₂O will be = 46 + 32 + 64 + (10 x 18) = 322
The weight of water Wa = 0.1 kg = 100 g
The weight of the solute (Glauber's salt) Wb = 6.0 g
Kf = 1.86 k kg. mol⁻¹
i (Vont Hof factor) = 3
According to the relation, DTf = kf / MB x 1WB/WA x 1000 x i
= 1.86 / 322 x 6.0 / 100 x 1000 x 3 = 1.039 K
So, the freezing point will be calculated as = 273 - 1.039 K = 271.96 K
Answered by
7
the correct answer is - 273.96 kelvin
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