Download App

Solutions — Chemistry STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceChemistrySolutions3 Marks
Question
Explain positive deviation from Raoult's law with an example.
✓

Answer

When the is a positive deviation in the mixture of two liquids A and B, the A-B attraction is weaker than the attraction between A-A and B-B, that is, in this situation the intermolecular force between the solute solvent molecules is less than that of the solute-solute and solvent-solvent molecules. Therefore, form such solutions, molecules of A and B can escape more easily than the pure component, due to whih the vapour pressure increases.
Example: Mixture of pure ethanol and acetone, there are hydrogen bonds between the molecules. When acetone is added to pure ethanol, its molecules comes between the hydrogen bonds of ethanol molecule and breaks them. Due to this intermolecular forces of attraction, this mixture shows positive deviation from Raoult's law.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "3 Marks Question" from Solutions→Solutions — all question types→Chemistry STD 12 Science question papers→Gujarat Board STD 12 Science question papers→Gujarat Board question paper generator→

Similar questions

Explain the importance of carbohydrate compounds.
→
Write the monomers used for getting the following polymers:
  1. Polyvinyl chloride.
  2. Teflon.
  3. Bakelite.
→
Indicate the steps in the preparation of:
$KMnO_4$ from pyrolusite ore.
→
Answer the following questions:
Give reasons:
  1. Among transition metals, the highest oxidation state is exhibited in oxoanions of a metal.
  2. $Ce^{4+}$ is used as an oxidising agent in volumetric analysis.
  3. $Zn^{2+}$​​​​​​​ salts are white while $Cu^{2+}$​​​​​​​ salts are blue.
→
Justify the placement of $O,\ S,\ Se,\ Te$ and $Po$ in the same group of the periodic table in terms of electronic configuration, oxidation state and hydride formation.
→
Explain the following: $H_3PO_3$ is diprotic.
→
Account for any two of the following:
  1. Amines are basic substances while amides are neutral.
  2. Nitro compounds have higher boiling points than the hydrocarbons having almost the same molecular mass.
  3. Aromatic amines are weaker bases than aliphatic amines.
→
Free energies of formation $(\triangle _fG)$ of $MgO(s)$ and $CO(g)$ at $1273K$ and $2273K$ are given below.
$\Delta_{\text{f}}\text{G}[\text{MgO(s)}]=-941\text{kJ/ mol}\text{ at }1273\text{K}$ $\Delta_{\text{f}}\text{G}[\text{MgO(s)}]=-314\text{kJ/ mol}\text{ at }2273\text{K}$
$\Delta_{\text{f}}\text{G}[\text{CO(g)}]=-439\text{kJ/ mol}\text{ at }1273\text{K}$ $\Delta_{\text{f}}\text{G}[\text{CO(g)}]=-628\text{kJ/ mol}\text{ at }2273\text{K}$
On the basis of above data, predict the temperature at which carbon can be used as a reducing agent for $MgO(s).$
→
How will you convert the following:
  1. Impure Nickel to pure Nickel
  2. Zinc blende to Zinc metal
  3. $[Ag(CN)_2]^-$ to $Ag$
→
Explain magnetic properties of transition element.
→