Advertisements
Advertisements
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)
Advertisements
उत्तर
We know that the depression in freezing point is given by
`DeltaT_`
Here,
van't Hoff factor = i
Depression in freezing point, ΔTf=1.62 K
Kf for benzene=4.9 K kg mol−1
Mass of benzoic acid, ws=3.9 g
Mass of benzene, W=49 g
Molar mass of benzoic acid, Ms=122 g mol−1
Substituting the values, we get
`1.62 = (ixx4.9xx(3.9xx1000))/(122xx49)`
`rArri=(1.62xx122xx49)/(4.9xx3.9xx1000)`
= 0.51
As the value of i < 1, benzoic acid is an associated solute.
APPEARS IN
संबंधित प्रश्न
Derive van’t Hoff general solution equation.
Calculate the amount of benzoic acid (C6H5COOH) required for preparing 250 mL of 0.15 M solution in methanol.
How will you convert the following in not more than two steps:
Benzoic acid to Benzaldehyde
We have three aqueous solutions of NaCl labelled as ‘A’, ‘B’ and ‘C’ with concentrations 0.1 M, 0.01 M and 0.001 M, respectively. The value of van’t Hoff factor for these solutions will be in the order ______.
The values of Van’t Hoff factors for KCl, NaCl and K2SO4, respectively, are ______.
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"`
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)
Consider the reaction
\[\begin{bmatrix}\begin{array}{cc}
\phantom{.......}\ce{CH3}\\
\phantom{....}|\\
\ce{CH3CH2CH2 - \overset{⊕}{N} - CH2CH3}\\
\phantom{....}|\\
\phantom{.......}\ce{CH3}
\end{array}\end{bmatrix}\]\[\ce{OH^- ->[Heat] ?}\]
Which of the following is formed in a major amount?
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]
Why is boiling point of 1 M NaCl solution more than that of 1 M glucose solution?
