Depression in Freezing Point of the Solvent

IMPORTANT

Depression in Freezing Point of the Solvent: Overview

This Topic covers sub-topics such as Depression in Freezing Point, Anti-Freezing Agents, Molal Freezing Point Depression Constant and, Molal Freezing Point Depression Constant Using Molar Heat of Fusion

Important Questions on Depression in Freezing Point of the Solvent

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What mass of ethylene glycol (molar mass =62.0g​ mol1)  must be added to 5.50 kg of water to lower the freezing point of water from  0°C to10.0°C?  (Kf  forwater=1.86Kkgmol1)

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Calculate the depression in the freezing point of water when 10 g of  CH3CH2CHClCOOH is added to 250 g of water.  Ka=1.4×103, Kf=1.86 K kg mol1.

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Calculate the freezing point of a solution containing 18 g glucose, C6H12O6and68.4gsucrose,C12H22O11in200g of water. The freezing point of pure water is 273 K and Kf for water is 1.86 K kg mol1.

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The freezing point of a solution containing 0.2 g of acetic acid in 20.0 g of benzene is lowered by 0.45°C. The molar mass (g/mol) of acetic acid from this data and the value of van’t Hoff factor would be (for benzene, Kf=5.12 K kg mol-1)

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Assertion: Camphor is usually used in molecular mass determination.

Reason: Camphor has low cryoscopic constant and therefore, causes greater depression in freezing point.

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Assertion: Sodium chloride is used to clear snow on the roads.

Reason :Sodium chloride depresses the freezing point of water.

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PtCl4·6H2O can exist as a hydrated complex. 1 molal aqueous solution has a depression in freezing point of 3.72°C. Assume, 100% ionization and Kf H2O=1.86 K mol-1 kg. Then the complex is

MEDIUM
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When 9.45 g of ClCH2COOH is added to 500 mL of water, its freezing point drops by 0.5°C. The dissociation constant of ClCH2COOH is x×10-3. The value of x is _______. (Rounded off to the nearest integer)

KfH2O=1.86 K kg mol-1

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How much amount of NaCl should be added to 600 g of water (ρ=1.00 g/mL) to decrease the freezing point of water to -0.2°C?_______(The freezing point depression constant for water =2 K kg mol-1)

Round off your answer to the nearest integer after multiplying with 10.

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X g of NaCl was dissolved in 400 g water and cooled up to -0.5 °C, due to which 28 g of ice is separated out from the solution. Then the value of x is (Given : KfH2O=1.86 K kg mol-1). Assuming complete dissociation of salt. Give answer to the nearest integer.

MEDIUM
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Find the pH of HA aq.solution at 25°C. If its same equimolal aqueous solution compared to urea solution show depression in freezing point in the ratio 12 :10. Ka of HA=10-5, log2=0.3, log3=0.48, log5=0.7

Round off the answer to the nearest integer after multiplying with 10.

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Which of the following statements is false?

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31 g of an unknown molecular material is dissolved in 500 g of water. The resulting solution freezes at 271.14 K. Calculate molar mass of the material in gmol-1.(KfH2O = 1.86 K kg mol-1 , TofH2O= 273K)

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If van't Hoff factor for KCl is 1.8. What is the boiling point of 0.75 m  solution of KCl in water Kb=0.5°Ckg/mol?
 

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The freezing point (in C) of a solution containing 0.1 g of K3Fe(CN)6 (Mol.wt.329)  in 100 g of water Kf=1.86 K kg mol-1 is :

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An aqueous solution containing 6% by weight of urea and 9% by weight of glucose. What will be its approximate freezing point? KfH2O=1.86 K kg mol-1

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Which of the following aqueous solution has highest melting point ?

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A 0.2 molal aqueous solution of a weak acid HX is 20% ionised. The freezing point of this solution is:

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The depression in freezing point of 0.01M aqueous CH3COOH solution is 0.02046°1 M urea solution freezes at -1.86°C. Assuming molality equal to molarity, pH of CH3COOH solution is :

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An aqueous solution of 10% NaCl (ideal) is cooled. It will allow some