Ncert Solutions Chemistry Class 11th
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pH of 0.08 mol dm–3 HOCl solution is 2.85. Calculate its ionisation constant.
pH of 0.08 mol dm–3 HOCl solution is 2.85. Calculate its ionisation constant.
This is a Short Answer Type Questions as classified in NCERT Exemplar
Ans: pH of HOCL = 2.85
But, - pH = log [H+]
-2.85=log [H+]
= -3.15 = log [H+]
[H+]=anti log3.15
[H+]= 1.413* 10-3
or weak mono basic acid
[H+]= C
= = =
=24.957 10-6
=2.4957 10-5
A sparingly soluble salt gets precipitated only when the product of concentration of its ions in the solution (Qsp) becomes greater than its solubility product. If the solubility of BaSO4 in water is 8 × 10–4 mol dm–3. Calculate its solubility in 0.01 mol dm–3 of H2SO4.
A sparingly soluble salt gets precipitated only when the product of concentration of its ions in the solution (Qsp) becomes greater than its solubility product. If the solubility of BaSO4 in water is 8 × 10–4 mol dm–3. Calculate its solubility in 0.01 mol dm–3 of H2SO4.
This is a Short Answer Type Questions as classified in NCERT Exemplar
Ans: The chemical equation is given below-
&nb
pH of a solution of a strong acid is 5.0. What will be the pH of the solution obtained after diluting the given solution a 100 times?
pH of a solution of a strong acid is 5.0. What will be the pH of the solution obtained after diluting the given solution a 100 times?
This is a Short Answer Type Questions as classified in NCERT Exemplar
Ans: Given with the pH = 5 as, pH= - log [ H+ ]
[ H+ ] =10-5M
On 100 times dilution-
[ H+ ] =10-7M.
What are metallic/interstitial hydrides? How do they differ from molecular hydrides?
What are metallic/interstitial hydrides? How do they differ from molecular hydrides?
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These are formed by many d-block and/block elements. However, the metals of group 7, 8 and 9 do not form hydride. Unlike saline hydrides, they are almost always non- stoichiometric, being deficient in hydrogen. For example, LaH 2.8
On the basis of the equation pH = – log [H+ ], the pH of 10–8 mol dm–3 solution of HCl should be 8. However, it is observed to be less than 7.0. Explain the reason
On the basis of the equation pH = – log [H+ ], the pH of 10–8 mol dm–3 solution of HCl should be 8. However, it is observed to be less than 7.0. Explain the reason
This is a Short Answer Type Questions as classified in NCERT Exemplar
Ans: Here concentration of water cannot be neglected since the solution is very dilute. pH will be less than 7.0. Hence, the total concentration is given as -
[ H3O+ ] =10-8+10-7M.
The value of Kc for the reaction 2HI (g) ? H2 (g) + I2 (g) is 1 × 10–4
At a given time, the composition of reaction mixture is
[HI] = 2 × 10–5 mol, [H2] = 1 × 10–5 mol and [I2] = 1 × 10–5 mol
In which direction will the reaction proceed?
The value of Kc for the reaction 2HI (g) ? H2 (g) + I2 (g) is 1 × 10–4
At a given time, the composition of reaction mixture is
[HI] = 2 × 10–5 mol, [H2] = 1 × 10–5 mol and [I2] = 1 × 10–5 mol
In which direction will the reaction proceed?
This is a Short Answer Type Questions as classified in NCERT Exemplar
Ans: At a given time the reaction quotient Q for the reaction will be given by the expression:
Q= = = = 0.25
= 2.5×10−1
As the value of the reaction quotient is greater than the value of Kc i.e. 
Arrange the following in increasing order of pH.
KNO3 (aq), CH3COONa (aq), NH4Cl (aq), C6H5COONH4 (aq)
Arrange the following in increasing order of pH.
KNO3 (aq), CH3COONa (aq), NH4Cl (aq), C6H5COONH4 (aq)
This is a Short Answer Type Questions as classified in NCERT Exemplar
Ans: Correct order of pH is -
NH4Cl C6H5COONH4 KNO3 CH3COONa
Salts of strong acid and strong base do not hydrolyse and form neutral solution thus, pH will be nearly 7 of KNO3?
In sodium acetate,
Conjugate acid of a weak base is always stronger. What will be the decreasing order of basic strength of the following conjugate bases?
OH– , RO– , CH3COO– , Cl–
Conjugate acid of a weak base is always stronger. What will be the decreasing order of basic strength of the following conjugate bases?
OH– , RO– , CH3COO– , Cl–
This is a Short Answer Type Questions as classified in NCERT Exemplar
Ans: Conjugate acid of a weak base is always stronger and conjugate base of weak acid is always strong.
The weak acids are:
⇒H2O, ROH, CH3COOH, HCl
⇒HCl > CH3COOH > ROH > H2O
⇒ Conjugate base order ⇒ OH−>RO−>CH3COO−>Cl−
How can production of hydrogen from water gas be increased by using water gas shift reaction?
How can production of hydrogen from water gas be increased by using water gas shift reaction?
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Water-gas shift reaction: The water-gas shift reaction is a chemical reaction in which carbon monoxide reacts with steam in the presence of a catalyst to form carbon dioxide and hydrogen.
CO+H2+H2O → CO2+2H2
Ionisation constant of a weak base MOH, is given by the expression
kb=
Values of ionisation constant of some weak bases at a particular temperature are given below:
Base
K b
Dimethylamine
5.4 × 10–4
Urea
1.3 × 10–14
Pyridine
1.77 × 10–9
Ammonia
1.77 × 10–5
Arrange the bases in decreasing order of the extent of their ionisation at equilibrium. Which of the above base is the strongest?
Ionisation constant of a weak base MOH, is given by the expression
kb=
Values of ionisation constant of some weak bases at a particular temperature are given below:
|
Base |
K b |
|
Dimethylamine |
5.4 × 10–4 |
|
Urea |
1.3 × 10–14 |
|
Pyridine |
1.77 × 10–9 |
|
Ammonia |
1.77 × 10–5 |
Arrange the bases in decreasing order of the extent of their ionisation at equilibrium. Which of the above base is the strongest?
This is a Short Answer Type Questions as classified in NCERT Exemplar
Ans: Higher the value of Kb stronger will be the base.
Kb- 5.4 * 10-4 >1.77 * 10-5 > 1.77 * 10-9> 1.3 * 10-14
Decreasing order of basic strength.
Dimethylamine > Ammonia > Pyri