Home
NCERT Solution
Class 11
Chemistry
Equilibrium
the first ionization constant of h2s is 9 1 times...

Question:
The first ionization constant of H₂S is 9.1 × 10^–8. Calculate the concentration of HS^– ion in its 0.1M solution. How will this concentration be affected if the solution is 0.1M in HCl also ? If the second dissociation constant of H₂S is 1.2 × 10^–13, calculate the concentration of S^2– under both conditions.

Answer:

(i) To calculate the concentration of HS^- ion:

Case I (in the absence of HCl):

Let the concentration of HS^- be x M.

H₂S ↔ H⁺ + HS^-

C_i 0.1 0 0

C_f 0.1-x x x

Then K_a1 = [H⁺] [ HS^-] / H₂S

9.1 × 10^–8= xx / 0.1-x

(9.1 × 10^–8) (0.1-x) = x²

Taking 0.1 - x M ; 0.1M, we have

(9.1 × 10^–8) (0.1) = x²

9.1 x 10^-9= x²

Case II (in the presence of HCl):

In the presence of 0.1 M of HCl, let [HS^-] be y M.

Then, H₂S ↔ H⁺ + HS^-

C_i 0.1 0 0

C_f 0.1-y y y

Also, HCI ↔ H⁺ + CI^-

0.1 0.1

Now, K_a1 = [H⁺] [ HS^-] / H₂S

K_a1 = [y] [0.1+y] / [0.1-y]

9.1 × 10^–8= y x 0.1 / 0.1 (∵ 0.1-y; 0.1M) (and 0.1+y; 0.1M)

9.1 × 10^–8= y

⇒ [ HS^-] = 9.1 × 10^–8

(ii) To calculate the concentration of [S^2-]:

Case I (in the absence of 0.1 M HCl):

HS^- ↔ H⁺ + S^2-

HS^- = 9.54 x 10^-5 M (From first ionization, case I)

Let S^2-be X.

Also, [H⁺] = 9.54 x 10^-5 M (From first ionization, case I)

K_a2 = (9.54 x 10^-5) (X) / (9.54 x 10^-5)

1.2x10-13 = X = S^2-

Case II (in the presence of 0.1 M HCl):

Again, let the concentration of HS^- be X' M.

1
0
0
Report?

Report a problem on Specifications:

Email id:

Comments

< Previous Question

Next Question >

SELECT ex_no,question,question_no,id,chapter FROM question_mgmt as q WHERE courseId='2' AND subId='9' AND ex_no!=0 AND status=1 and id!=3079 ORDER BY views desc, last_viewed_on desc limit 0,10

Popular questions of class 11 Chemistry

The mass of an electron is 9.1 × 10^–31 kg. If its K.E. is 3.0 × 10^–25 J, calculate its wavelength.

Calculate the amount of carbon dioxide that could be produced when

(i) 1 mole of carbon is burnt in air.

(ii) 1 mole of carbon is burnt in 16 g of dioxygen.

(iii) 2 moles of carbon are burnt in 16 g of dioxygen.

Calculate the wavelength of an electron moving with a velocity of 2.05 × 10⁷ ms^–1.

Balance the following redox reactions by ion – electron method :

(a) MnO₄^–(aq) + I^–(aq) → MnO_{2 (s)} + I_2(s) (in basic medium)

(b) MnO₄ ^– (aq) + SO_{2 (g)}→ Mn²⁺ (aq) + HSO₄^– (aq) (in acidic solution)

(d) Cr₂O₇ ^2– + SO_2(g) → Cr³⁺ _(aq) + SO₄^2–(aq) (in acidic solution)

In a process, 701 J of heat is absorbed by a system and 394 J ofwork is done by the system. What is the change in internal energy for the process?

What will be the minimum pressure required to compress 500 dm³ of air at 1 bar to 200 dm³ at 30°C?

In a reaction A + B2 → AB2 Identify the limiting reagent, if any, in the following reaction mixtures.

(i) 300 atoms of A + 200 molecules of B

(ii) 2 mol A + 3 mol B

(iii) 100 atoms of A + 100 molecules of B

(iv) 5 mol A + 2.5 mol B

(v) 2.5 mol A + 5 mol B

At 0°C, the density of a certain oxide of a gas at 2 bar is same as that of dinitrogen at 5 bar. What is the molecular mass of the oxide?

Which one of the following will have largest number of atoms?

(i) 1 g Au (s)

(ii) 1 g Na (s)

(iii) 1 g Li (s)

(iv) 1 g of Cl2(g)

Density of a gas is found to be 5.46 g/dm³ at 27 °C at 2 bar pressure. What will be its density at STP?

SELECT ex_no,question,question_no,id,chapter FROM question_mgmt as q WHERE courseId='2' AND subId='9' AND ex_no!=0 AND status=1 and id!=3079 ORDER BY last_viewed_on desc limit 0,10

Recently Viewed Questions of Class 11 Chemistry

0.3780 g of an organic chloro compound gave 0.5740 g of silver chloride in Carius estimation. Calculate the percentage of chlorine present in the compound.

What happens when

(a) Borax is heated strongly,

(b) Boric acid is added to water,

(d) BF₃is reacted with ammonia?

When an alkali metal dissolves in liquid ammonia the solution can acquire different colours. Explain the reasons for this type of colour change.

The pH of 0.005M codeine (C₁₈H₂₁NO₃) solution is 9.95. Calculate its ionization constant and pKb.

What are hybridisation states of each carbon atom in the following compounds ?

(i) CH₂=C=O,

(ii) CH₃CH=CH₂,

(iii) (CH₃)₂CO,

(iv) CH₂=CHCN,

(v) C₆H₆

Discuss the chemistry of Lassaigne's test.

Draw the Lewis structures for the following molecules and ions: H2S, SiCl4, BeF2, , HCOOH

State as to why

(a) a solution of Na₂CO₃ is alkaline ?

(b) alkali metals are prepared by electrolysis of their fused chlorides ?

Explain why is sodium less reactive than potassium?

In three moles of ethane (C₂H₆), calculate the following:
(i) Number of moles of carbon atoms.
(ii) Number of moles of hydrogen atoms.
(iii) Number of molecules of ethane.

< Previous Question

Next Question >

Popular questions of class 11 Chemistry

Recently Viewed Questions of Class 11 Chemistry

Comments

Comment(s) on this Question

Important links

Quick Links

Resources

Support