CHEMISTRY NOTES
CHAPTER # 1
Are you seeking out the notes of Chemistry bankruptcy 1 Chemical Equilibrium Class 10? here are we shared 10th magnificence Chemistry Notes Chapter 1 Chemical Equilibrium. We are sharing whole chapter wise short answer question, numerical, lengthy question, and test yourself....
CHEMICAL EQUILIBRIUM
SHORT ANSWER QUESTIONS :
QUESTION 1 : What is introduction of chemical equilibrium ?
ANSWER : We presume that most chemical and physical changes proceed to completion. A complete reaction is one in which all reactants have been converted into product. Most chemical reaction do not go to completion because products react themselves to form the reactants . As a result, after sometime no further change take place .
QUESTION 2 : Define Reversible Reactions and give example ?
ANSWER : Quantities of Reactants and products remain unchanged , and it seems that the reaction has stopped . In fact, these reaction do not stop : rather they take place on both directions at equal rate and attain the equilibrium state . Such reactions are called reversible reactions .
"For example "
Many examples of physical and chemical equilibrium are found in nature , like Oxygen, water, plants etc .
QUESTION 3 : Define Products and Reactants and give example ?
ANSWER : In a chemical reactions, the substances that combine are called Reactants . And the new substances formed are called Products.
" FOR EXAMPLE" When H2 and O2 combine they form H2O ( Product).
QUESTION 4 : What are Irreversible Reactions ?
ANSWER : Most of the reactions, in which the products do not recombine to form reactants are called Irreversible reactions . They are supposed to complete and are represented by putting a single arrow
( → ) between the reactants and products .
QUESTION 5 : What are Reversible reactions ?
ANSWER : Reactions in which the products can combine to form reactants are called Reversible Reactions . These reactions never go to completion . They are presented by a double row ( ⇆ ) between reactants and products.
QUESTION 6 : Define Forward reaction ?
ANSWER : Reaction between hydrogen and iodine is one of the reactants, iodine is purple, while the product hydrogen iodide is colorless. On heating, hydrogen and iodine vaporous in a closed flask , hydrogen iodide is formed . As a result , purple color of iodine fades at reacts to form colorless hydrogen iodide. This reaction is called as Forward Reactions .
QUESTION 7 : What is Reverse Reaction ?
ANSWER : Hydrogen iodide acts are reactants and produces hydrogen and iodine vapors . This reaction is reverse of the above. Therefor, it is called Reverse Reactions. When both of these reactions are written together as a Reversible Reaction, they are represented as :
showing establishment of reversible reaction.
ANSWER : When the rate of forward reaction is the same as the rate of reserve reactions . The composition of the reaction mixture remain constant. It is called a Chemical Equilibrium State .
QUESTION 9 : Define dynamic equilibrium state ?
ANSWER : When reaction does not stop , only the rates of forward and reserve reactions become equal to each other but take place in opposite directions. This is called Dynamic Equilibrium State .
" Rate of forward reaction = Rate of reserve reaction "
ANSWER : " Forward Reactions "
1 . It is a reaction in which reactants react to form product.
2 . It takes place from left to right.
3. An initial stage the rate of forward reaction is very fast.
4. It slows down gradually .
" Reserve Reactions "
1. It is a reaction in which products react to produce reactants .
2. It takes place from right to left .
3. In the beginning the rate of reserve reaction is negligible .
4. It speeds up gradually .
QUESTION 11 : Differentiate between Macroscopic Characteristics of Dynamic Equilibrium ?
ANSWER : A few important characteristics features of dynamic equilibrium are given below.
1 : An equilibrium is achievable only in a closed system ( in which substances can neither leave or nor enter )
2 : At equilibrium state a reaction does not stop. Forward and Reserve reactions keep on taking place at the same rate but in opposite directions.
3 : At equilibrium state , the amount ( concentration ) of reactants and products do not change. Even physical properties like color, density, etc. remain the same .
4 : An equilibrium state is attainable from either way , i.e . starting from reactants or from products.
5 : An equilibrium state can be disturbed and again achieved under the given conditions of concentration, pressure and temperature.
QUESTION 12 : Definition of LAW OF MASS ACTION ?
ANSWER : law of mass action, law stating that the rate of any chemical reaction is proportional to the product of the masses of the reacting substances, with each mass raised to a power equal to the coefficient that occurs in the chemical equation. This law was formulated over the period 1864–79 by the Norwegian scientists Cato M.
Goldberg and Peter Wage but is now of only historical interest. This law was useful for obtaining the correct equilibrium equation for a reaction, but the rate expressions it provides are now known to apply only to elementary reactions.
" FORMULA LAW OF MASS ACTION "
![K= \frac {[A']^{\alpha '} [B']^{\beta '}\ldots} {[A]^\alpha [B]^\beta \ldots}](https://www.gstatic.com/education/formulas2/472522532/en/law_of_mass_action.svg)
 | = | equilibrium constant |
 | = | psychometric coefficients for the reaction |
![[A]](https://www.gstatic.com/education/formulas2/472522532/en/law_of_mass_action_law_of_mass_action_var_3.svg) | = | concentration of reactant A |
![[B]](https://www.gstatic.com/education/formulas2/472522532/en/law_of_mass_action_law_of_mass_action_var_4.svg) | = | concentration of reactant B |
![[A']](https://www.gstatic.com/education/formulas2/472522532/en/law_of_mass_action_law_of_mass_action_var_5.svg) | = | concentration of product A |
![[B']](https://www.gstatic.com/education/formulas2/472522532/en/law_of_mass_action_law_of_mass_action_var_6.svg) | = | concentration of product B |
" TEST YOUR SELF "
QUESTION 13 : Define static equilibrium and give example ?
ANSWER : When reaction ceases to proceed, it is called STATIC EQUILIBRIUM. This happen mostly in physical phenomenon. For example , a building remains standing rather than falling down because all the forces acting on it are balanced. This is an example of Static equilibrium.
QUESTION 14 : Why reversible reactions never complete ?
ANSWER : Because in these reactions product can recombine to form reactants . These reactions can proceed in both directions. For example : forward and reserve.
QUESTION 15 : Why the amount,s of reactants and products do not change at equilibrium in reversible reactions ?
ANSWER : Because in reversible reaction decomposition and combination take place at the same rate but in opposite direction. As a result amounts of products and reactants do not change.
QUESTION 16 : Point out the coefficients of each in the following ?
ANSWER : Hypothetical reactants :
a) : 2A + 3B ⇋ 4C + 2D
Component : A B C D
Coefficients : 2 3 4 2
b) : 4X ⇋ 2Y + 3Z
Component : X Y Z
Coefficients : 4 2 3
c) : 2M + 4N ⇋ 5O
Component : M N O
Coefficients : 2 4 5
QUESTION 17 : Write the equilibrium constants expressions for the following reactions ?
ANSWER : "Reactions "
a) : 2NO2(g) ⇋ N2O4(g)
Kc = [ N2 O4 ] / [ ND 2 ] 2
b) : PCI3(g) + CI2(g) ⇋ PCI5(g)
Kc = [ PCI 5 ] / [ PCI3 ] + [ CI2 ]
c) : 2SO2(g) + O2(g) ⇋ 2SO3(g)
Kc = [ SO3 ]2 / [ SO2]2 + [ O2 ]
QUESTION 18 : Define Predicting Direction of a reaction ?
ANSWER : Direction of a reaction at a particular moment can be predicted by inserting the concentration of the reactants and products at the particular moment in the equilibrium expression. Consider the gaseous reaction of hydrogen with iodine.
QUESTION 19 : Explain Predicting extents of a reaction ?
ANSWER : Numerical value of the equilibrium constant predicts the extent of a reaction. It indicates to which extent reactants are converted to products. In fact, it measures how far a reaction proceeds before establishing equilibrium state.
In general, there are three possibilities of predicting extent of reactions ...
(a) Large numerical value of Kc.
(b) Small numerical value of kc.
(c) Numerical value of Kc is neither small nor large.
QUESTION 20 : Why the reversible reactions do not go to completion ?
ANSWER : Reversible reaction do not go to completion because products recombine to form reactants and reaction i.e.
" forward and reserve "
if a reaction has large value of Kc it indicates that reactions has almost gone to completion because at the equilibrium position the reactions mixtures consists of almost all products and reactants are negligible.
QUESTION 21 : If a reaction has large value of Kc will it go to completion and why ?
ANSWER : The large value of Kc indicates that at equilibrium position the reaction mixture consist of almost all products and reactants are negligible. ( The reaction has almost gone to completion). For example , oxidation of carbon monoxide goes to completion at 1000 K.
2CO(g) + O2(g) ⇋ 2CO2(g) Kc = 2.2 × 1022
QUESTION 22 : Which types of reactions do not go to completion ?
ANSWER : Reversible reactions never go to completion or they attain equilibrium after a certain time. ∙ So,the concentration of reactants and products is stable at equilibrium, it neither increases nor decreases . One example of a reversible reaction is the reaction of hydrogen gas and iodine vapor to form hydrogen iodide.
QUESTION 23 : Why the reaction mixture does not have 50% reactants and 50% products at equilibrium position ?
ANSWER : At a dynamic equilibrium, a closed system of chemicals in a reversible reaction have equal rates of its forward reaction and its backward reaction. However, they may not necessarily have equal composition of its reactants and products. This is because the composition of reactants and products is governed by other factors, such as the temperature, the initial concentrations of the reactants and the psychometric ratios of reactants and products. Therefore, while the rates of the forward and backward reactions are equal, the composition ratios may not have to be. However, it is important to note that the concentrations of reactants and products remain constant at dynamic equilibrium. They may not be at the same concentration, but they will remain constant when an equilibrium is established.
CONCEPT DIAGRAM
There is complete paragraph wise short questions and test yourself answers . For further numerical and long questions we share very soon .
Note:
We are providing all subjects notes from 6 to 10 and College / University level, Sargodha and Punjab Board.
0 Comments