A colligative property is a property of a solution that is dependent on the ratio between the total number of solute particles (in the solution) to the total number of solvent particles. Colligative properties are not dependent on the chemical nature of the solution’s components. Thus, colligative properties can be linked to several quantities that express the concentration of a solution, such as molarity, normality, and molality. The four colligative properties that can be exhibited by a solution are:

• Boiling point elevation
• Freezing point depression
• Relative lowering of vapour pressure
• Osmotic pressure

Colligative properties are properties of a solution which depend only on the number of particles like ions or molecules of the solute in a definite amount of the solvent but not on the nature of the solute.

In chemistry, colligative properties are those properties of solutions that depend on the ratio of the number of solute particles to the number of solvent molecules in a solution, and not on the nature of the chemical species present. The number ratio can be related to the various units for concentration of a solution, for example, molarity, molality, normality (chemistry), etc. The assumption that solution properties are independent of nature of solute particles is only exact for ideal solutions, and is approximate for dilute real solutions. In other words, colligative properties are a set of solution properties that can be reasonably approximated by assuming that the solution is ideal.

Only properties which result from the dissolution of nonvolatile solute in a volatile liquid solvent are considered. They are essentially solvent properties which are changed by the presence of the solute. The solute particles displace some solvent molecules in the liquid phase and therefore reduce the concentration of solvent, so that the colligative properties are independent of the nature of the solute. The word colligative is derived from the Latin colligatus meaning bound together. This indicates that all colligative properties have a common feature, namely that they are related only to the number of solute molecules relative to the number of solvent molecules and not to the nature of the solute.

Electrochemical Cells

The chemical changes which involve the flow of electric current are called electrochemical changes.

These are broadly of two types:

1) Electrochemical cells or Galvanic cells

These constitute the electrochemical reactions in which chemical energy is converted to electrical energy. In these cells, spontaneous redox reaction is used to generate an electric current.

The devices in which chemical energy of a spontaneous redox reaction is converted into electrical energy are called electrochemical cells or galvanic cells. In these devices, the Gibbs energy of the spontaneous redox reaction is converted into electrical work which may be used for running a motor or other electrical gadgets like heater, fan, geyser, etc.

An early example of a galvanic cell is a Daniel cell which was invented by the British chemist John Daniel in 1836. Daniel cell was constructed on the basis of the following spontaneous redox reaction :

Zn (s) + Cu²⁺ (aq) ⇔ Zn²⁺ (aq) + Cu (s)

Molar conductivity

Molar conductivity of a solution at a given concentration is the conductance of volume V of a solution containing one mole of electrolyte kept between two electrodes with an area of cross-section A and distance of unit length.

Ʌ_m = К/c

Here,

c = concentration in moles per volume
К = specific conductivity
Ʌ_m = molar conductivity.

Butenal on oxidation gives butanoic acid.

Butanoic acid can be obtained by oxidation of butan-1-ol.

The most common reagent used for oxidation of alcohols is chromium (Vl) reagents including chromic acid (H₂CrO_4­), potassium dichromate (K₂Cr₂O₇) and chromic anhydride (CrO₃).

Answer:

molar mass ofCaCl2.6H2O = 40 + 2(35.5) + 6(18)

                                              = 219 g mol^-1

Molarity = weight of solute * 1000 / molar mass of solute * volume

  1 = weight of solute * 1 / 219 * 1

weight of solute = 219 gm

here volume is already given in litre so we don't need to multiply with (1000).

Rate of change of concentration ammonia = -0.2 * 10^-4 M/s

Explanation:

Given: N2+3H2 →2NH3. During the formation of ammonia 2 moles of nitrogen disappear in 1min. The volume of vessel is 1L.

Solution:

N2 + 3H2 -----> 2NH3

-d[H2] / dt = 0.3 * 10^-4 M/s

Rate = (1/3)(-d[H2] / dt)

        = (1/2) (d[NH3] /dt)

       = d[NH3] / dt

       = (2/3)( -d[h2]/dt)

       = d [NH3]/dt

d[NH3] /dt = -2/3 (0.3 * 10^-4)

 d[NH3] /dt = -0.2 * 10^-4 M/s

Rate of change of concentration ammonia is the answer.

A n s w e r : Molecular crystal
E x p l a n a t i o n :
wax crystals are molecular crystals, in which constituent particles are molecules having inter particle forces are Vander Waal’s forces.

On July 7, HRD Minister Ramesh Pokhriyal announced a major CBSE syllabus reduction with 30% of the syllabus slashed for the year 2020-21 for classes 9 to 12 because of the reduction in classroom teaching time due to the Covid-19 pandemic and lockdown.

CBSE has rationalized the syllabus with the help of suggestions from NCERT and the same has been notified by a new CBSE notification as well.

Deleted syllabus of CBSE Class 12 Chemistry

For revised syllabus click on the given link:

• <a href="http://cbseacademic.nic.in/web_material/CurriculumMain21/revisedsyllabi/SrSecondary/REVISEDChemistry_2020-21.pdf" target="_blank">REVISED - Chemistry</a>

Crystal meth is the common name for crystal methamphetamine, a strong and highly addictive drug that affects the central nervous system. There is no legal use for it.

The intermolecular forces of attraction that are present in solids are very strong.  The constituent particles of solids have fixed positions i.e., they are rigid. Hence, solids have a definite volume.

1. 

Racemisation occurs in case of SN1 reaction.

Explanation:

• SN1 is the process of substitution reaction where there is a carbocation formation and then a nucleophilic attack on that carbocation to form a product.

• The SN1 reaction intermediate is a carbocation.

• Now a carbocation is a sp2 hybrid structure which is planar.

• So the nucleophile can attack from any side of the plane.

• So the product that is formed is a mixture of both the stereoisomers.

• So the product is a racemic mixture.