important question of chemistry

 

Q.    what are the limitations of chemical equation

ANSWER.           Chemical equations have several limitations, including:

They do not take into account the physical state of the reactants and products, only their chemical formulas.

They do not indicate the relative proportions of reactants and products, only their stoichiometry.

They do not indicate the rate or mechanism of a reaction, only the overall change in the reactants and products.

They do not indicate any changes in energy that occur during a reaction, only the changes in the chemical formulas.

They do not take into account the effects of catalysts or inhibitors on a reaction.

They do not indicate the actual yield of a reaction, only the theoretical yield based on stoichiometry.

They do not take into account any side reactions that may occur.

OR, 

Chemical equations do not show the physical state (solid, liquid, gas) of reactants and products

They do not show the proportion of reactants and products

They do not show how fast or how a reaction happens

They do not show any energy changes during a reaction

They do not show the effects of catalysts or inhibitors

They do not indicate the actual yield of a reaction

They do not show any side reactions that may occur.

Q. state any two  chemical reaction with an example .

ANS.           A chemical reaction is a process that involves the rearrangement of atoms in one or more reactants to form one or more new substances, called products.

Synthesis reactions: two or more reactants combine to form a single product. For example: 2H2 + O2 -> 2H2O

Decomposition reactions: a single reactant breaks down into two or more products. For example: 2H2O -> 2H2 + O2

Q.        balance the following equation by partial equation method          Cu+ConcHNO3 => Cu(no3)2+NO2+H2O

ANS.          The balanced equation using the partial equation method is:

Cu + Conchno3 = Cu(NO3)2 + NO2 + H2O

Write the reactants and products as they are given:

Cu + Conchno3 = Cu(NO3)2 + NO2 + H2O

Identify the elements that appear on one side of the equation but not on the other. In this case, the elements are Cu, N, and O.

balance the element separately by using the coefficient

Cu = Cu

N = N

O = O

now add the coefficient to balance the equation

Cu + Conchno3 = Cu(NO3)2 + NO2 + H2O

2 + 2Conchno3 = 2Cu(NO3)2 + 2NO2 + 2H2O

check if the equation is balanced

Cu + Conchno3 = Cu(NO3)2 + NO2 + H2O

2Cu + 4Conchno3 = 2Cu(NO3)2 + 4NO2 + 4H2O 

The equation is now balanced.

Note: the compound "conchno3" is not a standard chemical formula, it might be a typo or it could be a specific compound.

Q.    STATE MODERN PERIODIC LAW ,WHAT ARE ITS ADVANTAGE?

ANS.         The modern periodic law states that the properties of the elements are periodic functions of their atomic numbers. The modern version of the periodic table arranges the elements in order of increasing atomic number and groups elements with similar properties together.

The advantages of the modern periodic law include:

It allows for the prediction of the chemical and physical properties of elements based on their atomic number.

It helps in the discovery of new elements and the prediction of their properties.

It facilitates the study of chemical reactions and the behavior of elements in compounds.

It allows for the classification and organization of the elements, making them easier to study and understand.

It helps in understanding the electronic structure of atoms and their reactivity.

It helps in developing new technologies and materials by providing a deeper understanding of the elements and their properties.

Q.     WHAT DO YOU MEAN BY ELECTRONEGETIVITY 

ANS.       Electronegativity is a measure of an atom's ability to attract electrons in a chemical bond. It ranges from 0.7 for cesium to 4.0 for fluorine, and is used to predict the polarity of bonds and chemical reactions, as well as in the design of new materials.

OR

Electronegativity is a measure of an atom's ability to attract electrons to itself in a chemical bond. It is a relative scale, and the values of electronegativity are determined by comparing the ability of different atoms to attract electrons. The most electronegative element is fluorine, with an electronegativity value of 4.0, while the least electronegative element is cesium, with an electronegativity value of 0.7.

In a chemical bond, the atom with the higher electronegativity will have a greater attraction for the shared electrons, and will be more negative than the other atom. The difference in electronegativity between the two atoms in a bond is a measure of the polarity of the bond; a bond between two atoms with similar electronegativities will be nonpolar, while a bond between atoms with a large difference in electronegativity will be polar, with the electron density being skewed towards the more electronegative atom.

Electronegativity has a wide range of applications in chemistry, such as in the prediction of chemical reactions and the behavior of compounds. It is also used in the development of new technologies, such as in the design of materials with specific properties.

Q.       STATE MENDELEEV PERIODIC LAW  WRITE ANY FOUR ;IMITATION OF MENDELEEV PERIODIC TABLE

ANS.   Mendeleev's Periodic Law states that the properties of elements are periodic functions of their atomic number.

Elements in the same group (vertical column) have similar chemical and physical properties.

As atomic number increases, elements have a tendency to gain electrons and form negative ions.

The atomic size of elements generally increases as one moves down a group.

Elements in the same period (horizontal row) have similar valence electron configurations.

Limitations of Mendeleev's Periodic Table:

It did not account for the existence of isotopes.

It did not account for the role of subatomic particles in determining the properties of elements.

It did not predict the discovery of new elements.

It did not account for the existence of elements yet to be discovered

Q.  DEFENATON OF GAS LAWS 

ANS.     Gas laws describe the relationship between the pressure, volume, and temperature of a gas. There are several important gas laws, including:

Boyle's Law: states that the volume of a gas is inversely proportional to its pressure, at constant temperature.

Charles's Law: states that the volume of a gas is directly proportional to its temperature, at constant pressure.

Gay-Lussac's Law: states that the pressure of a gas is directly proportional to its temperature, at constant volume.

Avogadro's Law: states that the volume of a gas is directly proportional to the number of moles of the gas, at constant temperature and pressure.

Ideal gas law: states that the pressure, volume, and temperature of an ideal gas are related by the equation PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature.

Q.    WITH EQ OF GAS LAW 

ANS.          Yes, here are the equations for the gas laws mentioned earlier:

Boyle's Law: PV = k (where P is the pressure, V is the volume, and k is a constant)

Charles's Law: V = kT (where V is the volume, T is the temperature, and k is a constant)

Gay-Lussac's Law: P = kT (where P is the pressure, T is the temperature, and k is a constant)

Avogadro's Law: V = k (where V is the volume, n is the number of moles, and k is a constant)

Ideal gas law: PV = nRT (where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature).

Note that in all of these equations, the variables on one side of the equation are directly proportional to the variables on the other side, as long as the temperature and the number of moles are constant

Q.      IDEAL GAS , RELATION, DIEFINE/ DERIVE PV=NRT 

ANS.      The ideal gas law, PV = nRT, can be derived from the kinetic theory of gases. Kinetic theory states that gases are made up of a large number of small particles (such as atoms or molecules) that are in constant motion. The particles collide with each other and with the walls of the container, which results in the pressure of the gas.

To derive the ideal gas law, we can start with the following assumptions:

The gas is made up of a large number of particles, each of which is in constant motion.

The particles are point particles, meaning they have no volume and do not interact with each other except for through collisions.

The collisions between particles and the walls of the container are perfectly elastic, meaning no energy is lost in the collisions.

The temperature of the gas is proportional to the average kinetic energy of the particles.

With these assumptions, we can calculate the pressure of the gas as follows:

The pressure of the gas is equal to the force exerted on the walls of the container per unit area.

The force exerted on the walls of the container is equal to the number of particles striking the walls per unit time multiplied by the force exerted by each particle on the walls.

The number of particles striking the walls per unit time is equal to the number of particles per unit volume multiplied by the average velocity of the particles.

The average velocity of the particles is proportional to the square root of the temperature.

The force exerted by each particle on the walls is proportional to the velocity of the particle.

By combining these equations, we can obtain the ideal gas law, PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant and T is the temperature.

It is important to note that this is a theoretical derivation and the ideal gas law is only an approximation, the real gases deviate from ideal gas laws under certain conditions such as high pressure and low temperature

===>> RELATION 

The ideal gas law, PV = nRT, relates the pressure (P), volume (V), number of moles (n), and temperature (T) of a gas, with the ideal gas constant (R) being a proportionality factor. The ideal gas constant, R, has a value of 8.314 J/mol·K or 0.0821 L·atm/mol·K, depending on the units used for pressure and volume

It is important to note that this equation only applies to ideal gases, which do not take into account the interactions between gas particles, such as attraction and repulsion forces. Real gases deviate from this equation under certain conditions, such as high pressure and low temperature. However, it is still a useful tool to predict and understand the behavior of gases under different conditions.

The equation PV = nRT is often used to solve problems in thermodynamics, such as calculating the volume of a gas at a certain pressure and temperature, or the pressure of a gas at a certain volume and temperature. It can also be used to calculate the amount of a gas that is required to fill a certain volume at a certain pressure and temperature.

In addition to the ideal gas law, there are other gas laws such as Boyle's law, Charles's law, Gay-Lussac's law and Avogadro's law which also describe the relationship between pressure, volume, temperature and moles of gas. The ideal gas law can be derived from these laws by combining them.

Q.     DEFFERNCE BETWEEN IDEAL AND REAL GAS 

An ideal gas is a theoretical concept that assumes that a gas consists of a large number of point particles that do not interact with each other except for through perfectly elastic collisions. In other words, an ideal gas is a gas that follows the gas laws perfectly, without any deviation.

On the other hand, a real gas is a gas that exists in the real world and deviates from the ideal gas laws under certain conditions such as high pressure and low temperature. Real gases have a finite size and interact with each other through attractive and repulsive forces.

The differences between ideal and real gases can be summarized as follows:

Ideal gases have no intermolecular forces, while real gases do. This means that real gases experience more resistance to compression than ideal gases.

Ideal gases have zero volume, while real gases have a finite volume. This means that real gases take up more space than ideal gases at the same pressure and temperature.

Ideal gases have infinite compressibility, while real gases have a limited compressibility. This means that real gases can only be compressed to a certain point before their volume becomes zero.

Ideal gases are not affected by temperature, while real gases are affected by temperature. This means that real gases exhibit a deviation from ideal gas laws as the temperature changes.

The ideal gas law PV = nRT is only an approximation, the real gases deviate from ideal gas laws under certain conditions such as high pressure and low temperature.

It's important to note that while real gases deviate from the ideal gas laws, the ideal gas laws still provide a useful tool to predict and understand the behavior of gases under different conditions.

Q,   WHAT IS SOLUBILITY ?

Solubility is the ability of a substance to dissolve in a solvent (another substance) to form a homogeneous solution. It is a measure of how much of a solute (the substance being dissolved) can be dissolved in a given amount of solvent at a given temperature and pressure.

OR 

Solubility is the ability of a substance to dissolve in a solvent, forming a homogeneous solution. It is a measure of how much of a solute can be dissolved in a given amount of solvent at a given temperature and pressure. The solubility of a substance can be affected by factors such as temperature, pressure, and the nature of the solvent and solute. It can be expressed in units such as molarity, molality or weight/volume percentage. A solution can be either saturated or unsaturated if it contains the maximum or less than the maximum amount of solute that can be dissolved in a solvent at a given temperature and pressure respectively.

Q.        WRITE SHORT NOTE ON RAOULTS LAW , SHOW YOUR FAMILIARITY WITH RAOULTS LAW 

ANS.        Raoult's law is a law that describes the behavior of the vapor pressure of a liquid in a mixture of liquids. It states that the vapor pressure of a liquid in a mixture is directly proportional to the mole fraction of that liquid in the mixture. In other words, the vapor pressure of a liquid in a mixture is equal to the vapor pressure of the pure liquid multiplied by its mole fraction. Mathematically, it can be represented as:

P1 = X1 * P1°

where P1 is the vapor pressure of the liquid in the mixture, X1 is the mole fraction of the liquid in the mixture, and P1° is the vapor pressure of the pure liquid.

Raoult's law is only applicable to ideal solutions, where the intermolecular forces between the solute and solvent are negligible. In other words, it assumes that the solute and solvent do not interact with each other and that the vapor pressure of the liquid is not affected by the presence of other liquids.

This law is only valid for ideal solutions, for non-ideal solutions, when the intermolecular forces between the solute and solvent are not negligible, the law does not hold true and other laws such as Henry's law or Dalton's law of partial pressure is used.

It's important to note that Raoult's law is only applicable to liquid solutions and is not valid for solutions in other states of matter, such as solids or gases.

SHOW YOUR FAMILIARITY WITH RAOULTS LAW  IN SHORT.

Raoult's Law is a fundamental concept in thermodynamics that states that the vapor pressure of a solution is directly proportional to the mole fraction of the solute in the solution. This means that if you add a solute to a solvent, the vapor pressure of the solution will be lower than the vapor pressure of the pure solvent

In short, Raoult's Law states that the vapor pressure of a solution is equal to the vapor pressure of the pure solvent multiplied by the mole fraction of the solvent in the solution. This relationship can be represented mathematically as:

P_solution = P_solvent * X_solvent

Where P_solution is the vapor pressure of the solution, P_solvent is the vapor pressure of the pure solvent and X_solvent is the mole fraction of the solvent in the solution.

It's important to note that Raoult's Law is only applicable for ideal solutions, which are solutions that have no interactions between the solute and solvent molecules. Real solutions deviate from Raoult's Law due to the presence of intermolecular forces between the solute and solvent molecules.

Q. WRITE SHORT NOTE ON VISCOSITY AND SURFACE TENSION

ANS.      Viscosity is a property of a fluid that describes its resistance to flow. It is a measure of a fluid's thickness or "stickiness". Fluids with high viscosity, such as honey, are thicker and more resistant to flow than fluids with low viscosity, such as water. Viscosity is affected by temperature and pressure, with most fluids becoming less viscous as temperature increases and pressure decreases.

Surface tension is a property of a liquid that describes the cohesive forces between its molecules at its surface. It is a measure of the "skin" that forms on the surface of a liquid, and it is responsible for phenomena such as the shape of droplets and the ability of some insects to walk on water. Surface tension is affected by temperature, with most liquids becoming less surface-tensive as temperature increases.

Both viscosity and surface tension are related to the forces between the molecules of a substance, viscosity is related to the internal friction within a fluid, while surface tension is related to the cohesive forces at the surface of a liquid.