Advertisements
Advertisements
प्रश्न
When 19.5 g of F – CH2 – COOH (Molar mass = 78 g mol−1), is dissolved in 500 g of water, the depression in freezing point is observed to be 1°C. Calculate the degree of dissociation of F – CH2 – COOH.
[Given: Kf for water = 1.86 K kg mol−1]
Advertisements
उत्तर
Given: Mass = 19.5 g
Molar mass = 78 g mol−1
ΔTf = 1°C
Kf = 1.86 K kg mol−1
ΔTf = Kf × Molality × i
Molality = `"Moles of solute"/"Kg of solvent"`
= `(19.5/78)/(500/100)`
= 0.5 M
i = `(Δ"T"_"f")/("K"_"f" xx "Molality")`
= `1/(1.86 xx 0.5)`
i = 1.07
For F – CH2 – COOH ⇒ i = 1 + α
α = i − 1
= 1.07 − 1
α = 0.07
APPEARS IN
संबंधित प्रश्न
3.9 g of benzoic acid dissolved in 49 g of benzene shows a depression in freezing point of 1.62 K. Calculate the van't Hoff factor and predict the nature of solute (associated or dissociated).
(Given : Molar mass of benzoic acid = 122 g mol−1, Kf for benzene = 4.9 K kg mol−1)
How van’t Hoff factor is related to the degree of dissociation?
Give reasons for the following
Elevation of the boiling point of 1 M KCl solution is nearly double than that of 1 M sugar solution.
Predict whether van’t Hoff factor, (i) is less than one or greater than one in the following:
CH3COOH dissolved in water
Van’t Hoff factor i is given by the expression:
(i) i = `"Normal molar mass"/"Abnormal molar mass"`
(ii) i = `"Abnormal molar mass"/"Normal molar mass"`
(iii) i = `"Observed colligative property"/"Calculated colligative property"`
(iv) i = `"Calculated colligative property"/"Observed colligative property"`
What is the expected each water van't Hoff factor for and K4[F4(CN6)] when it completely dissociated in waters.
A storage battery contains a solution of H2SO4 38% by weight. At this concentration, Van't Hoff Factor is 2.50. At the battery content freeze temperature will be ______ K.
(Kf = 1.86 K Kg mol−1)
The degree of dissociation of Ca(NO3)2 in a dilute aqueous solution containing 7 g of the salt per 100 g of water at 100°C is 70%. If the vapour pressure of water at 100°C is 760 mm. The vapour pressure of the solution is ______ mm.
A molecule M associates in a given solvent according to the equation \[\ce{M <=> (M)_n}\]. For a certain concentration of M, the van't Hoff factor was found to be 0.9 and the fraction of associated molecules was 0.2. The value of n is ______.
Why is boiling point of 1 M NaCl solution more than that of 1 M glucose solution?
