The ionization constant of propanoic acid is 1.32 x 10-5. Calculate the degree of ionization of the acid in its 0.05M solution and also its pH. What will be its degree of ionization if the solution is 0.01M in HCl also?
Let the degree of ionization of propanoic acid be α.
Then, representing propionic acid as HA, we have:
HA + H2O ↔ H3O+ + A-
(0.05-0.0α) ≈ 0.05 0.05α 0.05α
Ka = [H3O+] [A-] / [HA]
= (0.05α)(0.05α) / 0.05
= 0.05 α2
Then, [H3O+] = 0.05α = 0.05 x 1.63 x 10-2 = Kb . 15 x 10-4 M
∴ pH = 3.09
In the presence of 0.1M of HCl, let α' be the degree of ionization.
Then, [H3O+] = 0.01
[A-] = 0.05α'
[HA] = 0.05
Ka = 0.01 x 0.05α' / 0.05
⇒ 1.32 x 10-5 = 0.1 α'
α' = 1.32 x 10-3
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) → MnO2 (s) + I2(s) (in basic medium)
(b) MnO4 – (aq) + SO2 (g) → Mn2+ (aq) + HSO4– (aq) (in acidic solution)
(c) H2O2 (aq) + Fe 2+ (aq) → Fe3+ (aq) + H2O (l) (in acidic solution)
(d) Cr2O7 2– + SO2(g) → Cr3+ (aq) + SO42– (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?
What is the equilibrium concentration of each of the substances in the equilibrium when the initial concentration of ICl was 0.78 M ?
2ICl (g) ↔ I2 (g) + Cl2 (g); Kc = 0.14
Explain why the following systems are not aromatic?
What are the various factors due to which the ionization enthalpy of the main group elements tends to decrease down a group?
Pressure is determined as force per unit area of the surface. The SI unit of pressure, Pascal is as shown below:
1Pa = 1N m–2
If mass of air at sea level is 1034 g cm–2, calculate the pressure in Pascal.
Explain the difference in properties of diamond and graphite on the basis of their structures.
Calculate the pH of the following solutions:
(a) 2 g of TlOH dissolved in water to give 2 litre of solution.
(b) 0.3 g of Ca(OH)2 dissolved in water to give 500 mL of solution.
(c) 0.3 g of NaOH dissolved in water to give 200 mL of solution.
(d) 1mL of 13.6 M HCl is diluted with water to give 1 litre of solution.
Write the expression for the equilibrium constant, Kc for each of the following reactions:
(i) 2NOCl (g) ↔ 2NO (g) + Cl2 (g)
(ii) 2Cu(NO3)2 (s) ↔ 2CuO (s) + 4NO2 (g) + O2 (g)
(iii) CH3COOC2H5(aq) + H2O(l) ↔ CH3COOH (aq) + C2H5OH (aq)
(iv) Fe3+ (aq) + 3OH– (aq) ↔ Fe(OH)3 (s)
(v) I2 (s) + 5F2 ↔ 2IF5
List gases which are responsible for greenhouse effect.
Calculate a) ΔG0 and b) the equilibrium constant for the formation of NO2 from NO and O2 at 298K
NO (g) + ½ O2 (g) ↔ NO2 (g)
where ΔfG0 (NO2) = 52.0 kJ/mol
ΔfG0 (NO) = 87.0 kJ/mol
ΔfG0 (O2) = 0 kJ/mol
For the reaction at 298 K,
2A + B → C
ΔH = 400 kJ mol-1and ΔS = 0.2 kJ K-1mol-1
At what temperature will the reaction become spontaneous considering ΔH and ΔS to be constant over the temperature range?