Category: Chemistry Notes PPT

Solute is that component (usually solid) that gets dissolved in a solvent to produce a homogeneous mixture. The amount of solute is usually less in quantity compared to the solvent. The concentration represents the amount of solute present in a chemical solution with respect to the amount of solvent. Some examples of solutes include sodium chloride, sugar (See figure 1), and carbon dioxide.
Dissolution of a solute in a solvent to form a solution                                                         

• Presence or absence of water as solvent
•The amount of solute added

The route and mobility of an electron in an atom can be described using quantum numbers. The Schrodinger equation must be met when the quantum numbers of all the electrons in an atom are summed together.

Quantum numbers are the values of the conserved quantities in a quantum system. Electronic quantum numbers (quantum numbers that describe electrons) are numerical quantities that provide solutions to the Schrodinger wave equation for hydrogen atoms.

Brief Introduction of Quantum Numbers 

Quantum numbers are used to define the trajectory and movement of an electron within an atom. Additionally, the quantum numbers of every electron in an atom are combined; it should obey the Schrodinger equation.

Notably, this is a crucial topic in your syllabus. Not only do you need to learn about this topic for your syllabus, but also because it is vital for future curriculum in various examinations. Consequently, do learn the significance of quantum numbers in detail.

The following four quantum numbers can be used to fully characterise all of the characteristics of an atom’s electrons:

• n is the principal quantum number.

• The quantum number of orbital angular momentum (also known as the azimuthal quantum number) is indicated by the letter l.

• ml stands for a magnetic quantum number.

• ms stands for the electron spin quantum number.

What are Quantum Numbers?

The position and energy of an electron in an atom are described by quantum numbers, which are a collection of numbers. An atom is made up of a vast number of orbitals that are distinguishable from one another by their shape, size, and spatial orientation. The orbital properties are utilised to thoroughly define an electron’s state and are expressed in terms of three numbers: 

• Principal quantum number

• Azimuthal quantum number

• Magnetic quantum number

• Spin quantum number

The numbers that designate and distinguish various atomic orbitals and electrons present in an atom are known as quantum numbers. Quantum Numbers are a collection of four numbers that may be used to obtain all of the information about all of the electrons in an atom, including their energy, location, space, kind of orbital occupied, and even the direction of that orbital.

Quantum Number Values

• No two electrons in an atom may have the same set of quantum numbers, according to the Pauli exclusion principle. A half-integer or integer value is used to represent each quantum number.

• The number of the electron’s shell is the primary quantum number, which is an integer. The value is one or more (never 0 or negative).

• The value of the electron’s orbital is represented by the angular momentum quantum number (s=0, p=1). l is less than or equal to n-1 and bigger than or equal to zero.

• With integer values ranging from -l to l, the magnetic quantum number is the orbital’s orientation. As a result, for the p orbital, where l=1, m might be -1, 0, or 1.

• The spin quantum number is a half-integer value that is either -1/2 (referred to as “spin down”) or 1/2 (referred to as “spin up”) (called “spin up”).

Principal Quantum Number

This principal quantum number portrays the electron shell or energy level of an atom. Here, the value on ‘n’ starts from one and gradually increases to the shell that contains the outermost electron of a particular atom. For instance, in caesium (Cs), the outermost valence electron within the shell has energy level 6. Hence, the ‘n’ value of an electron in caesium can range from 1 to 6. 

Moreover, particles that are in a time-independent potential have the nth given value of Hamiltonian, as per the Schrodinger equation. Hamiltonian’s nth eigenvalue refers to the energy, i.e. E with contribution from angular momentum. However, the term that involves J2 is not considered here. 

Therefore, this number only depends on the distance between an electron and its nucleus, which is the radial coordinate ‘r’. Since the average number rises with ‘n’, quantum states with various principal quantum numbers are said to be a part of different shells.

Azimuthal Quantum Number

The azimuthal quantum number is commonly known as the angular or orbital quantum number. Moreover, it describes the subshell of an electron and its magnitude of the orbital angular momentum via relation. Additionally, in spectroscopy or chemistry where 

ℓ = 0, it is known as an s orbital,

ℓ = 1 is a p orbital,

ℓ = 2 represents a d orbital,

ℓ = 3 is an f orbital.

Therefore, the value of ℓ varies from 0 to n-1, because the first p orbital where ℓ=1 arrives in the second electron shell, i.e. n=2. Likewise, the first d orbital, i.e. ℓ=2, appears within the third shell, which is n=3, and so on. The azimuthal quantum number is very significant in chemistry, as it identifies the shape of an atomic orbital, and has a powerful effect on chemical bonds and bond angles. 

Magnetic Quantum Number

Magnetic quantum numbers articulate the energy available in a subshell and estimate the orbital angular momentum along a specific axis. Moreover, values associated with mℓ ranges between – to ℓ, but integer steps are associated. Additionally, the ‘s’ is a subshell where ℓ=0 has one orbital. Therefore, mℓ of an electron within a ‘s’ subshell will be zero always. 

Additionally, the ‘p’ subshell, i.e. ℓ=1 comprises three orbitals. It is also known as three ‘dumbbell-shaped’ clouds. Hence, the mℓ of an electron in this ‘p’ subshell should be either -1, 0, 1.

Lastly, the ‘d’ subshell where ℓ=2 has five orbitals. Furthermore, here mℓ has values starting from -2 to +2. Additionally, the value of mℓ quantum number here is associated with orbital orientation.

Spin Projection Quantum Number

The fourth number on this list, quantum numbers spin, describes intrinsic angular momentum or ‘spin’ of an electron within an orbital. Moreover, it provides a projection of the spin angular momentum (s) along a particular axis.

Additionally, the values of ms r start from –s to s. Here, ‘s’ defines the spin quantum number, an inherent property of particles. An electron that has a spin ‘s’ = 1/2, its ms will be ‘±’, confirming its spin and opposite spin. Moreover, every electron in any particular orbital should have different spins according to ‘Pauli Exclusion Principle’. Hence, an orbital cannot contain more than 2 electrons. 

Background of Quantum Numbers

The work of Broglie and Bohr
have established how electrons have diverse discrete energy levels associated with their atomic radius. This model offered a comparatively, simpler spherical view. Moreover, this model by Bohr and Broglie indicated how the energy level of electrons is related to their principal quantum number. However, there are no numerical ways present in this model to classify additional behaviour of an electron in space. 

Furthermore, Schrodinger’s equation offered three additional quantum numbers to describe an electron’s behaviour in a more complicated multi-electron atom. This model was opposite to what Bohr and Broglie have done previously. Moreover, it opened new possibilities in the field of studying quantum numbers.

Additionally, based on these two models and further contributions from John Lennard-Jones and Slater, the Hund-Mulliken theory has been developed. Moreover, this theory is regarded as the most prominent system of nomenclature in the history of quantum mechanics.

Moreover, this nomenclature has incorporated Hund-Mulliken’s theory along with Bohr’s energy levels, and observations made on electron spin on spectroscopy and Hund’s rule.

Multiplicative Quantum Numbers

One negligible yet confusing point, which is related to the quantum numbers is that a large portion of these numbers is additive. Hence, in an elementary particle reaction, the sum value of such a number must be similar before and after a reaction. 

However, some of these numbers, which are typically called parity, are multiplicative. It means their product is preserved. Moreover, these multiplicative quantum numbers are affiliated with a symmetry. Hence, applying it results in transformation twice as equal to that of not doing anything, i.e. involution.

Atomic Orbital

Solving the Schrodinger equation results in obtaining a set of mathematical functions called wave functions. It indicates the probability of locating electrons at specific energy levels in an atom. Additionally, this wave function for an electron within an atom is called the atomic orbital. Moreover, it indicates a space where the probability of finding an electron is higher.

Quantum numbers Class 11 chemistry is not a very difficult chapter to prepare if you get an interactive session with a subject expert. You will learn the concepts, real-life examples and how to solve equations with ease in such sessions. 

Therefore, if you are searching for such an interactive session on quantum numbers, then visit the official app of . Subject experts from across the country conduct live and interactive classes which can be immensely helpful in clearing any doubt that you might have.

The reaction rate, also known as the rate of reaction, is the rate at which a chemical reaction occurs, and is proportional to the increase in product concentration per unit time and the decrease in reactant concentration per unit time. The speed at which the reaction proceeds varies a lot. 

Rate of reaction examples: The oxidative rusting of iron under Earth’s atmosphere is a gradual process that can take several years, while the combustion of cellulose in a fire occurs in fractions of a second. The rate of most reactions decreases as the reaction progresses. The rate of a reaction can be calculated by tracking changes in concentration over time.

The rate of a chemical reaction is often expressed in terms of the concentration (amount per unit volume) of a substance produced in a unit of time or the concentration (amount per unit volume) of a reactant consumed in a unit of time. It can also be expressed in terms of the number of reactants consumed or products produced in a given amount of time.

This article will study reaction rate, rate of chemical reaction, to define rate of reaction, and rate of reaction formula.

Factors Affecting Rate of Reaction

The nature of the reaction, concentration, strain, reaction order, temperature, solvent, electromagnetic radiation, catalyst, isotopes, surface area, stirring, and the diffusion limit are all factors that affect the reaction rate. Some reactions occur more quickly than others. The rate of a reaction is greatly affected by the number of reacting species, their physical state (solid particles move much more slowly than gases or those in solution), the complexity of the reaction, and other factors.

1. Concentration of Reactant

As defined by the rate law and explained by collision theory, the reaction rate increases with concentration. The number of collisions increases as the concentration of reactants rises. The rate of gaseous reactions increases as pressure rises, which is similar to a rise in gas concentration. While there are fewer moles of gas present, the reaction rate increases, and when there are more moles of gas present, it decreases. The pressure dependency is poor for condensed-phase reactions.

2. Electromagnetic Radiation

As a consequence, electromagnetic radiation can speed up or even make a reaction spontaneous by adding more energy to the reactant particles. This energy is stored in the reacting particles in one way or another, resulting in intermediate species that are easy to react. The particles gain more energy as the strength of light increases, and thus the rate of reaction increases.

3. Catalysts

By offering an alternative pathway with lower activation energy, the presence of a catalyst increases the reaction rate (in both forward and reverse reactions). At room temperature, platinum, for example, catalyzes the combustion of hydrogen with oxygen.

4. Isotope

Because of the relative mass difference between hydrogen and deuterium, the kinetic isotope effect induces a different reaction rate for the same molecule if it has different isotopes, typically hydrogen isotopes. The rate of reaction increases as the surface area increases in reactions on surfaces, such as during heterogeneous catalysis. This is due to the fact that more stable particles are exposed and can be struck by reactant molecules.

5. Stirring

For heterogeneous reactions, stirring can have a significant impact on the rate of reaction.

6. Diffusion

Diffusion is a limiting factor in certain reactions. The reaction rate coefficient takes into account all variables that influence a reaction rate, excluding concentration and reaction order (the coefficient in the rate equation of the reaction).

7. Temperature

The average kinetic energy of the reactants is measured by temperature. The kinetic energy of the reactants increases as the temperature rises. In other words, the particles are moving faster. Since the reactants are moving faster, further collisions will occur at a faster pace, raising the chances of reactants forming into products and therefore increasing the rate of reaction. A ten-degree increase in temperature causes the reaction rate to double. The temperature dependence of each reaction rate coefficient k is typically given by the Arrhenius equation:

k=Ae[^{-Ea/RT}]

8. Pressure

The concentration of gases increases as pressure rises, resulting in a faster rate of reaction. The reaction rate increases as the number of gaseous molecules decreases and decreases as the number of gaseous molecules increases.

As a result, it’s easy to see how pressure and concentration are related, and how they both influence reaction rates.

Average Rate of Reaction

Now consider the following reaction to achieve a better understanding.

For the given reaction below:

A → B

A reactant A undergoes a chemical reaction to produce a product B in this reaction. The concentration of any reactant or product is usually defined as [reactant] or [product]. As a result, A’s concentration can be expressed as [A] and B’s concentration as [B]. The start time, t=0 should be the time when the reaction starts.

Let’s take a look at the following situation:

At t = t₁,

The concentration of A = [A]₁

The Concentration of B = [B]₁

At t = t₂,

The concentration of A = [A]₂

The concentration of B = [B]₂

In the time interval between t₁ and t₂, we want to know the rate at which A (reactant) disappears and the rate at which the product B appears. As a result

Rate of Disappearance of [A] = [frac{[A]_{2} – [A]_{1}}{t_{2} – t_{1}}] = [frac{-Delta A}{Delta t}]

The negative sign indicates that the concentration of A is decreasing.

Rate of Appearance of [B] = [frac{[B]_{2} – [B]_{1}}{t_{2} – t_{1}}] = [frac{Delta B}{Delta t}]

Since A is the only reactant in the reaction and B is the only product produced, and since mass is conserved, the amount of A that has disappeared in the time interval t will be the same as the amount of B that has formed in the same time interval. So we can conclude that

The reaction rate = – A’s rate of disappearance equals B’s rate of appearance.

Rate of Reaction = [frac{-Delta A}{Delta t}] = [frac{Delta B}{Delta t}]

The above reaction shows that the disappearance of A is equal to the appearance of B.

Instantaneous Rate of Reaction

The rate of reaction at any given time is known as the instantaneous rate of reaction.

Assume that the time t has a very small value and is approaching zero. Now we have an infinitesimally small t, which is a very short time period and can be thought of as a single point in time. The instantaneous rate of reaction would be the average reaction rate.

Instantaneous Rate of Reaction = [frac{-dA}{dt}] =  [frac{dB}{dt}]

Did You Know?

The power dependence of rate on all reactant concentrations can be described as the order of the reaction. The rate of a first-order reaction,
for example, is solely determined by the concentration of one species in the reaction. The following are some features of a chemical reaction’s reaction order.

1. The number of species whose abundance directly affects the rate of reaction is defined by reaction order.

2. All the exponents of the concentration terms in the rate expression can be added to get it.

3. The stoichiometric coefficients corresponding to each species in the balanced reaction have no effect on the reaction order.

4. A chemical reaction’s reaction order is often determined by reactant concentrations rather than product concentrations.

5. The order of reaction can be expressed as an integer or as a fraction. It is also possible for it to have a value of zero.

The power-law form of the rate equation is commonly used to calculate the reaction order r = k[A]^x[B]^y is the expression for this form of the rate law.

What is Reduction Potential?

The electrode potential is called oxidation potential, and the reduction potential is termed as oxidation potential if the oxidation occurs at the electrode. Reduction involves a gain of electrons, and so, the electrode tendency to gain electrons is referred to as its reduction potential.

The potential equilibrium difference of the metal electrode and the solution surrounding it is known as the electrode potential. It is also described as the electrode tendency either to lose or gain electrons.

Reduction Potential Explanation

When a metal piece is immersed in a solution of its own ions, a potential difference is formed at the metal interface and the solution. The potential difference magnitude is a measure of the electrode tendency to undergo either reduction or oxidation or the tendency to either lose or gain the electrons.

The ion and metal represent half cell, and the reaction is the half-reaction. The immersed metal is called an electrode, and the potential occurred because of the reaction at the electrode interface. The solution is known as the electrode potential. Thereby, the electrode potential is described as the tendency of an electrode either to lose or gain electrons. If the reduction occurs at the electrode, it is defined as the reduction potential.

If the oxidation occurs at the electrode, it is referred to as the oxidation potential.

M → M²⁺ + 2e⁻

As metal ions start depositing on the metal surface and this develops a positive charge on the particular metal rod. Since oxidation is simply a reverse of reduction and thus the reduction potential is obtained from the oxidation potential just by changing the sign.

Generally, for an electrode:

Oxidation potential = – Reduction potential

As an example, in a zinc electrode, the standard oxidation potential can be represented as follows:

E[^{0}] ([frac{Zn}{Zn^{2+}}]) = 0.76v 

and the standard reduction potential can be given as follows:

E[^{0}] ([frac{Zn^{2+}}{Zn}]) = – 0.76v 

It is quite common practice to show all the electrode potentials as the reduction potentials.

Very recently, the reduction potential has been adopted by the department of the International Union of Pure and Applied Chemistry (IUPAC) for the electrode potential designation.

When the half-cell reaction is carried out with a temperature of 298K, and the electrode is suspended in one single molar solution concentration, the electrode potential can be defined as the standard electrode potential, and it can be represented by E[^{0}]. Moreover, the Standard electrode potential E[^{0}] enables one to assess the activity of thermodynamics of different chemical substances. However, there are no other methods available where we can measure its absolute value. The electrode potential of an electrode can be measured with respect to the standard hydrogen electrode.

The electrode potential of an electrode completely depends upon the concentration of ions in a solution in contact with the metal. In simple words, the oxidation potential of an electrode is inversely proportional to the ion concentration, whereas the reduction potential is directly proportional to the ion concentration.

Half Cells

As a cell, a battery has two half-cells separated with an electrolyte. The electrodes are required to connect the half cells to the external circuit. Every electrode can act as part of a redox couple, but none of these has to be.

The standard conditions for the hydrogen half-cell are the concentration of hydrogen [H⁺(AQ)], the pressure of hydrogen gas is given as 105Pa with a temperature of 298K.

The standard hydrogen half-cell can be used as a reference half-cell, whereas all the other half-cells are measured against it. An electrode potential list has been generated relative to the half-cell of standard hydrogen. The half-reaction in this half cell is given as follows:

2H⁺(aq) + 2e⁻ ⇌ H₂(g)

Electrodes potentials differ with the temperature, and thus, a standard temperature can be defined. This is given as 298K. By altering any ion concentration appearing in the half-reactions also affects the voltages, and thus, a standard concentration of 1.00 mol dm-3 can be chosen. Standard pressure is given as 105Pa.

The potential of a standard hydrogen half-cell can be described as 0.0V, which is a value chosen for convenience.

The half-cell’s standard electrode potential E[^{0}] can be defined as the potential difference between the half-cell and the standard hydrogen half-cell.

E[^{0}] values contain a sign based on whether the half-cell is at either a higher or lower positive potential compared to the standard hydrogen half-cell. The measurements are created at 298K with a metal dipping into a 1.00 mol dm-3 solution of the metal’s salt.

Effects of Reduction Potential

Generally, very late transition metal ions at the right end of the transition metal chain, including silver, copper, gold, contain a high potential for reduction. If the normal reduction potential of the lithium is more negative, then the oxidation potential of the lithium-ion is very positive.

Your school, residential complex, or other structure is composed of rocks and minerals. Additionally, the Earth is a goldmine of rocks and minerals. Have you ever wondered what distinguishes rocks from minerals? They are clever components of our daily lives. Cement, gold, granite, and volcanic are just a handful of the rocks and minerals we utilize daily. The terms ‘rocks and minerals are frequently used interchangeably. They cannot differentiate between rocks and minerals since they are unfamiliar with their names. However, it is critical to recognize the distinction between rocks and minerals. Let us examine the rocks and minerals and their significance.

What are Minerals?

A mineral is an inorganic solid that occurs naturally and has a distinct chemical composition and crystalline form.

The Earth comprises mineral components that exist either alone or in an infinite variety of combinations known as compounds. A mineral is made up of a single atom or molecule. A mineral is an inorganic material that occurs naturally and has a distinct chemical composition and organized atomic structure.

What are Rocks?

A rock is a dense, inorganic solid. Similar to minerals, stones are formed naturally. However, it’s worth noting that rock comprises two or more mineral grains. In other definitions, a rock is a substance composed of minerals or a mineral rock. Each stone is unique in shape, size, and texture. Geologists classify rocks into three categories: igneous, sedimentary, and metamorphic. Sandstone, limestone, marbles, and slate are all great examples.

What is the Difference Between Minerals and Rocks?

Usually, it’s challenging to differentiate between various minerals because some rocks are more delicate than granite. A slate is a kind of stone composed of clay composed of microscopic particles. Quartz, apatite, feldspar, kaolinite, and various other minerals can be used as particles. However, these crystals are not visible in the slate rock. The slate is identical in terms of texture and color. However, it cannot be classified as a mineral since its chemical composition and atomic structure is irregular. Minerals make up rocks, and minerals are self-contained and self-contained.

Uses of Rocks and Minerals

What are the uses of Rocks?

1. Building Foundations: The foundation must be laid first when constructing a house. This is because the building’s foundation binds all of the other components together. Blocks of rock are used for foundations, bridge pier construction, lighthouse construction, and retaining walls.

2. Making Electricity: Certain kinds of stones are utilized to produce energy. Coal is derived from a sedimentary rock composed of decaying plants. It is written of the leftovers of woody plants that are useless in marshy places and roasted into a solid mass.

3. Making Concretes: Most urban environments are composed of concrete, a naturally occurring rock. The use of stones accomplishes concreting. In the construction business, rock is crushed into finer particles and utilized as concrete. Limestone is the most utilized rock form in manufacturing Portland cement, paper, lime, and pesticides.
   

What are the uses of Minerals?

1. Electronics: Monitors and keyboards interact due to thin semiconductors such as silica. Indeed, microchips in electronic devices are composed of various natural components, ranging from silicon and germanium to gallium arsenide compounds.

2. Creating Cell Phone Components: A single smartphone requires the unique properties of around 30 different chemical elements, including a trace of gold, the world’s most conductor metal. The glass screen’s resilience is derived from silica sand, potassium, and other substances. 

3. Batteries: Lithium is used in virtually everything we have these days that require a lightweight battery, whether it’s lighting, telephones, or electric vehicles. Lithium batteries are available in various sizes, ranging from a 10-watt mobile phone battery to a 650-pound electric car battery containing nine pounds of lithium. 
   

Chemical Composition of Rocks and Minerals

• Chemical Composition of Rock: Rocks are composed of various compounds in different proportions by mass. The amounts of each compound determine the qualities of the rock. SiO₂ is found in sandstone; CaCO₃ is found in limestone.

• Chemical Composition of Minerals: Minerals can be classified into pure elements, simple compounds, and complex compounds. Simple compounds, such as water(H₂O), carbon dioxide(C0₂), and so on, are made of more than two or two atoms in fixed proportions. Complex compounds are substances in which bonds are formed.

• Eg:Steenstrupine-
  Na₁₄Ce₆Mn₂ + Mn₃ +Fe₂ + 5(Zr,Th)(SO₁₈)₂(PO₄)₇⋅3H₂ONa₁₄Ce₆Mn₂ + Mn₃ + Fe₅₂ +(Zr,Th)(SO₁₈)₂(PO₄)₇⋅3H₂O.

The segregation of different anions and cations and identification of the same in inorganic salts is known as salt analysis. This process is known via different names like qualitative analysis of inorganic salts or systematic qualitative analysis. Inorganic salts are separated into different ions with the help of different sorts of experiments done under laboratory conditions and putting the compounds under different distinct tests which confirm whether certain ions are present or not in the solution. 

For both theory and practical examinations, class 12 chemistry practicals salt analysis is a very important topic. If you were plagued until today with questions like ‘how to do salt analysis experiment class 12’, keep reading this article to get all your answers. 

A Walkthrough for Analysing Salts

1. Procure a considerable amount of salt on which you want to conduct an experiment.

2. Try to find out which anion group is present inside the salt. For most of this experiment, finding a wider group of ions is easier because, for groups, there is a common reagent against which a positive test result is obtained.

3. Once you find the group, take each anion of that group and perform positivity tests. 

4. Do the same group-wise experiment for cations, as you did for anions.

5. Once you find the group, take each cation of that group and perform positivity tests.

6. When both the cation and anion are obtained and identified, construct the chemical formula keeping in mind the valences of each ion. For example, if the cation found is Fe3+ and the anion found is Cl–, then the final inorganic salt result will be FeCl3. 

7. It is not mandatory that anions have to be found first. The order of finding each ion can also be swapped. 

Sample Answer Format

Below we provide a table that will help you conduct and write any practical experiment related to salt analysis class 12 with ease. 

Aim: To separate and identify the cation and anion present in the given inorganic salt.

Apparatus Needed: To be done by students. 

Procedure:

1. Anion Group Test – Preliminary

2. Final Anion Test – Confirmatory

3. Cation Group Test – Preliminary

4. Final Cation Test – Confirmatory

Shortcuts to Identify Ions

There are thousands of cations and anions which are there in nature and being discovered regularly. That is the reason it is impossible for students to test for each and every one of them. Also, owing to academic reasons, there are a certain set of popular ions which are asked to be experimented upon. We provide here a small checklist and a table that will help you identify cations much more easily than your peers. 

1. Make sure you correctly identify the colour of the cation. 

2. Most cations secrete a certain colour when mixed with other compounds. If a cation is coloured, you can skip the steps in between and go directly for the confirmatory test. 

3. Do not be confused if the salt is colourless. There are more colourless salts present than coloured salts. For colourless salts, the most fruitful test is the flame test, which proves the presence of three different cations. The most effective way to perform the flame test is to hold a pinch of the given salt and pour a minuscule amount of concentrated acid (say, hydrochloric acid) on it and then put it on a burner.

4. If even after this, there is no coloured cation seen to be present, move on to the preliminary test to identify the cation group, rather than single cations. 

5. Remember that there are certain cations that do not react with certain anions. For example, Sr2+, Pb2+, Ca2+ and Ba2+ do not have any known inorganic salt with the sulphate ion (SO42-). Another such example is the phosphate ion (PO43-) which forms salts only with group 0, group 1 and group 2 ions.

6. There are certain salts that are commonly asked in class 12 examinations. For example, NH4Br and CaCl2 are the two most popular salts that examiners ask students. Also, salts like calcium carbonate have a chalk-like appearance, which can be easily identified. Hence, even if it seems tough to identify salts, remembering these shortcuts can help save you a lot of time in the exam hall.

Pop Quiz 1

1. Identify the anion in the given inorganic salt – MnO2. 

1. Mn4+

2. O2- (Answer)

3. O–

4. Mn+

A Guide to Common Cations to Help with Salt Analysis

Keep in mind that multiple cations of the same group will have to undergo the same preliminary test, but undergo distinct confirmatory tests.

A Guide to Common Anions in Salt Analysis

Preliminary Tests (Anions & Acid Radicals)

The salt analysis for anions involves carrying out preliminary tests and group-wise to find the salt’s anion. If the test yields positive results, a confirmatory test needs to be carried out in order to confirm if the anion is present or not in the salt.

Preliminary Tests (Group 1 Anions)

Procedure: Take a small amount of salt solution in a test tube and add some drops of sulphuric acid (H2SO4) to it. If you observe no change, then you can carry out preliminary tests for Group 2 anions.

Preliminary Tests (Group 2 Anions)

Procedure: Take a few drops of concentrated sulfuric acid (H2SO4) in a test tube and add tiny amounts of salt to it. If you notice no change, then you can carry out preliminary tests for Group 3 anions.

Preliminary Tests (Group 3 Anions)

Significantly, Group 3 anions do not have any prominent preliminary test. These are the phosphate and sulphate ion groups, and if no positive test results are obtained, you must directly carry out the confirmatory tests for these.

The salt analysis is a very integral part of the CBSE chemistry syllabus for class 12. To learn more about the preliminary tests for cations, basic radicals and inorganic salts, check out our range of engaging study material and content available on the site. Download our app and register yourself for our free live demo classes.

Preliminary Test for Group 4 Cations

Experiment: To the original solution add the solid form of NH4Cl and then add NH4OH. Post adding the two compounds pass H2S gas through the solution. 

Preliminary Test for Group 5 Cations

Experiment: to the original solution add ammonia chloride, ammonium carbonate and ammonium hydroxide. If there is a precipitate which is white in colour then there is a possibility that the cation is that of the group 5 cation. After it, add dilute acetic acid (CH3COOH) to dissolve to white precipitate completely. Now perform the below mentioned test in the same sequence as written below.