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Ask QuestionPosted by Shruti Vasoya 5 years, 4 months ago
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Posted by Smaranika Mishra 5 years, 4 months ago
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Gaurav Seth 5 years, 4 months ago
Lyophilic colloids readily form a sol by bringing them into contact or by warming those with the medium due to their strong affinity for the dispersion medium.
For example, only heating with water in enough for preparing the sols of starch, gelatin, gum arabic etc.
However, it is not so easy to prepare the sols of lyophobic colloids practically as they have no affinity for the dispersion medium. Special methods are required for the preparation of lyophobic sols.
There are number of special methods used for preparation of lyophobic sols which can broadly be divided into the following categories:
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Dispersion methods
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Condensation or aggregation methods
Posted by S P 5 years, 4 months ago
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Posted by Abhishek Shukla 5 years, 4 months ago
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Gaurav Seth 5 years, 4 months ago
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
Posted by Raghvinder Singh 5 years, 4 months ago
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Gaurav Seth 5 years, 4 months ago
Henry’s law
- Henry’s Law establishes aquantitative relation betweenpressure and solubility of a gasin a solvent.
- This law is for gas-liquid solution.
- According to the law at a constant temperature, thesolubility of a gas in a liquid is directly proportional to thepressure of the gas.
- It can also be stated as - The partial pressure of the gas in vapour phase (p) is proportional to the mole fraction of the gas (x) in the solution.
- Mathematically,
p = KH x where KH = Henry’s law constant.
- At same temperature different gasses have different KH
- It is a function of the nature of the gas. At a given pressure increasing value of KH implies lower solubility of the gas in the liquid.
- Value of KH increases with the increase in temperature therefore solubility of gases increases with decreasing temperature. Due to this reason cold water is more sustainable for aquatic life than warm water.
Posted by Chandu Bindu 5 years, 4 months ago
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Gaurav Seth 5 years, 4 months ago
In this isomerism the isomers exist in dynamic equilibrium with each other.It arises due to migration of a hydrogen atom from one polyvalent atom to the other within the same molecule with necessary rearrangement of linkages.The isomers thus obtained are called tautomers and the phenomenon is called tautomerism. Tautomerism is also called desmotropism.
Posted by Devil ? 5 years, 4 months ago
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Yash Agarwal 5 years, 4 months ago
Posted by Hritick ❤❤ Be Unique 5 years, 4 months ago
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Yogita Ingle 5 years, 4 months ago
Molarity of solution =1/10M
Volume of solution =250mL
Milli-mole of oxalic acid =M×V(mL)=1/10 × 250
w/126 × 1000=1/10×250 0 (mol.wt. of oxalic acid =126=126)
∴w = (250×126)/ (10×1000) =3.15g
Posted by Choudhay Him 5 years, 4 months ago
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Yogita Ingle 5 years, 4 months ago
A catalyst increases rate of reacting by decreasing activation energy. and increasing the enthalpy change of the reaction
Posted by Dikshansh Kaushal 5 years, 4 months ago
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Posted by Hrushi 55 5 years, 4 months ago
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Gaurav Seth 5 years, 4 months ago
Given,
T1=269.15 K
T2 = 273.15
Molar mass of sucrose = 342 g mol–1
Molar mass of glucose = 180 g mol–1
ΔTf = Kf m
Here , m = w2x 1000/ M2XM1
273.15-269.15 = Kf x 10 x1000/ 342 x90
Kf = 12.3 K kg/mol
ΔTf = Kf m
= 12.3 x 10 x1000/ 180x90
= 7.6 K
Tf = 273.15 – 7.6 = 265.55 K
Posted by Suresh Sharma 5 years, 5 months ago
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Posted by Suresh Sharma 5 years, 5 months ago
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Harshini M S 5 years, 4 months ago
Posted by Suresh Sharma 5 years, 5 months ago
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Chandu Bindu 5 years, 4 months ago
Posted by Punam Thakur Punam Thakur 5 years, 5 months ago
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Posted by Suresh Sharma 5 years, 5 months ago
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Yogita Ingle 5 years, 5 months ago
Molybdenum (MO)
Electronic configuration: 1s22s22p63s23p63d104s24p64d55s1
The outer electronic configuration of Mo ( Z= 42 ) is 5s1
Posted by Radha Kumari 5 years, 5 months ago
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Gaurav Seth 5 years, 5 months ago
SN1 Reaction
The SN1 reaction is a substitution nucleophilic unimolecular reaction. It is a two-step reaction. In the first step, The carbon-halogen bond breaks heterolytically with the halogen retaining the previously shared pair of electrons. In the second step, the nucleophile reacts rapidly with the carbocation that was formed in the first step.
SN2 Reaction
This reaction follows second order kinetics and the rate of reaction depends upon both haloalkane as well as participating nucleophile. Hence this reaction is known as substitution nucleophilic bimolecular reaction. In this reaction, the nucleophile attacks the positively charged carbon and the halogen leaves the group.
It is a one-step reaction. Both the formation of carbocation and exiting of halogen take place simultaneously. In this process, unlike the SN1 mechanism, the inversion of configuration is observed. Since this reaction requires the approach of the nucleophile to the carbon bearing the leaving group, the presence of bulky substituents on or near the carbon atom has a dramatic inhibiting effect.
Posted by Abhishek Sahu???? 5 years, 5 months ago
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Yogita Ingle 5 years, 5 months ago
In the lanthanide series, +3 oxidation state is most common i.e., Ln(III) compounds are predominant. However, +2 and +4 oxidation states can also be found in the solution or in solid compounds.
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Shivam Kumari 5 years, 5 months ago
Pragati Gola 5 years, 5 months ago
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Kushal Saini 5 years, 4 months ago
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Posted by Ad Upadhyay 5 years, 5 months ago
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Gaurav Seth 5 years, 5 months ago
A “motif” is a generalised structure. Motifs are normally chemically similar but slightly different. As a simple example, a hydrocarbon motif on the end of a molecule could be:
Methyl, ethyl, propyl, butyl etc. It could also include isopropyl and related branched chains.
All similar chemically but with slightly different electronic and sterics effects.
You could do a similar thing with aromatic rings i.e. substituting different positions with different ( but similar) groups.
There is however normally quite a big change when you swap an alkyl chain for a aromatic ring do these two sets are not the same motif.
Posted by Preeti Yadav 5 years, 5 months ago
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Gaurav Seth 5 years, 5 months ago
The reactivity series
<section data-reactid=".1qh9egok9mi.0.0.0.1:0.2.0.$0.$1">In a reactivity series, the most reactive element is placed at the top and the least reactive element at the bottom. More reactive metals have a greater tendency to lose electrons and form positive ions.
A good way to remember the order of a reactivity series of metals is to use the first letter of each one to make up a silly sentence. For example: People Say Little Children Make A Zebra Ill Constantly Sniffing Giraffes.
</section>Posted by Preeti Yadav 5 years, 5 months ago
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Posted by Purvi Patel 5 years, 5 months ago
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Yogita Ingle 5 years, 5 months ago
According to Henry's law, the solubility of a gas in a liquid is directly proportional to the pressure of the gas.
X=Kh×P
X is the mole fraction of gas, Kh is Henry's law constant and P is the partial pressure of the gas.
Important applications of Henry's law:
1) In packing of soda cans: Soda water bottles are always packed under higher pressure to increase the solubility of CO2 gas.
2) In deep-sea diving: Nitrogen is more soluble than Helium in our blood. In the deep sea, the pressure is higher than at the surface of the water. When diver tries to come rapidly towards the surface of the water, pressure decreases and dissolved nitrogen comes back from blood and makes bubbles in veins. Hence, divers use oxygen diluted with helium.
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Gaurav Seth 5 years, 4 months ago
Lyophilic Colloids:-Substances like gum, gelatin, starch, rubber, which when mixed with a suitable liquid as the dispersion medium directly form the colloidal sol are called lyophilic and the sols thus are obtained are called lyophilic sols.
Ex. Muddy water.
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