Here,no. Of moles of water in 54 g = given weight/molecular weight

=54/18

=3

So, no. Of molecules=avogadro no. ×no. Of moles

=(6.022×10²³)×3

= 18.066 ×10²³ molecules

Aim:

To identify the anionic radicals present in an inorganic mixture of salts by performing various test.

Qualitative analysis involves the detection and identification of acidic and basic radicals present in inorganic salts. Inorganic salts are formed by the reaction of acids and bases or acidic oxides with a base or basic oxides.

Some of the examples of the reaction of acids and bases or acidic oxides with a base or basic oxides are

NaOH + HCl → NaCl + H₂O

CO₂ + 2NaOH → Na₂CO₃ + H₂O

KOH + HNO₃ → KNO₃ + H₂O

2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O

Continued.........

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<a href="https://ncert.nic.in/pdf/publication/sciencelaboratorymanuals/classXII/chemistry/lelm107.pdf" ping="/url?sa=t&source=web&rct=j&url=https://ncert.nic.in/pdf/publication/sciencelaboratorymanuals/classXII/chemistry/lelm107.pdf&ved=2ahUKEwjU4e_mua7tAhWLzDgGHUbgAi8QFjAQegQIHBAC" rel="noopener" target="_blank">systematic qualitative analysis - ncert</a>

When a slow dry current(stream) of oxygen is passed through silent electrical discharge, oxygen gets converted to ozone(about 10%). The product is known as ozonised oxygen.

 3O₂       →   2O₃    

It is an endothermic process. Use of a silent discharge is important in its preparation to prevent its decomposition

According to the valence bond theory, Electrons in a molecule occupy atomic orbitals rather than molecular orbitals. The atomic orbitals overlap on the bond formation and the larger the overlap the stronger the bond.

The important postulates of the valence bond theory are listed below.

1. Covalent bonds are formed when two valence orbitals (half-filled) belonging to two different atoms overlap on each other. The electron density in the area between the two bonding atoms increases as a result of this overlapping, thereby increasing the stability of the resulting molecule.
2. The presence of many unpaired electrons in the valence shell of an atom enables it to form multiple bonds with other atoms. The paired electrons present in the valence shell do not take participate in the formation of chemical bonds as per the valence bond theory.
3. Covalent chemical bonds are directional and are also parallel to the region corresponding to the atomic orbitals that are overlapping.
4. Sigma bonds and pi bonds differ in the pattern that the atomic orbitals overlap in, i.e. pi bonds are formed from sidewise overlapping whereas the overlapping along the axis containing the nuclei of the two atoms leads to the formation of sigma bonds.

• Nitrogen does not form pentahalides.
• The electronic configuration of nitrogen is 1s²2s²2p³.
• It has 5 valence electrons. In the valence shell, it has s and p orbitals. Nitrogen does not has vacant d orbitals. It cannot expand its octet. In other words, it cannot have more than 8 valence electrons. Hence, nitrogen cannot be pentavalent .

In amines, the hydrogen atoms in ammonia have been replaced one at a time by hydrocarbon groups. On this page, we are only looking at cases where the hydrocarbon groups are simple alkyl groups. The amine functional group contains a basic nitrogen atom with a lone pair of electrons. As such, the group is a derivative of ammonia, in which one or more hydrogen atoms have been replaced by a carbon-containing substituent. Amine groups bonded to an aromatic (conjugated cyclic) structure are known as aromatic amines.

Retention of configuration: A process in which the relative configuration of an atom is retained. If the atom in question is a stereocenter, retention of configurationusually (but not always) changes R absolute configuration into R, and S into S.

Inversion of configuration: A process in which the relative configuration of an atom is changed. If the atom in question is a stereocenter, inversion of configuration usually (but not always) changes R absolute configurationinto S, and S into R.
Racemization refers to the converting of an enantiomerically pure mixture (one where only one enantiomer is present) into a mixture where more than one of the enantiomers are present. If the racemization results in a mixture where the enantiomers are present in equal quantities

It is because of the Metal excess defect due to anionic vacancies.

When crystals of KCl are heated in an atmosphere of potassium vapour, the potassium atoms are deposited on the surface of the crystal. The Cl– ions diffuse to the surface of the crystal and combine with K atoms to give KCl. This happens by loss of electron by sodium atoms to form K+ ions. The released electrons diffuse into the crystal and occupy anionic sites. As a result the crystal now has an excess of potassium. The anionic sites occupied by unpaired electrons are called F-centres (for colour centre). They impart violet colour to the crystals of KCl. The colour results by excitation of these electrons when they absorb energy from the visible light falling on the crystals.

Entropy is a measure of randomness or disorder of the system.

The greater the randomness, higher is the entropy.

Solid state has the lowest entropy, the gaseous state has the highest entropy and the liquid state has the entropy in between the two.

Entropy is a state function. The change in its value during a process, is called the entropy change.

ΔS = S₂ -S₁ = ∑S _products – ∑S _reactants 

1) When a system absorbs heat ,the molecules start moving faster because kinetic energy increases. Hence, disorder increases. More the heat absorbed ,greater is the disorder.

2) For the same amount of heat absorbed at low temperature, the disorder is more than at high temperature. This shows that entropy change is inversely proportional to temperature.

ΔS = q_rev / T

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.

The CBSE syllabus has been reduced but care has been taken so that the learning outcomes remain the same and the students do not miss out on learning core concepts in various subjects.

Deleted syllabus of CBSE Class 12 Chemistry

Aromatic carboxylic acids do not undergo Friedal-Crafts reaction because the carboxylic group is strongly deactivating and the catalyst AlCl3AlCl3 (lewis acid ) gets bonded to the carboxylic group strongly 

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.

The CBSE syllabus has been reduced but care has been taken so that the learning outcomes remain the same and the students do not miss out on learning core concepts in various subjects.

Deleted syllabus of CBSE Class 12 Chemistry