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.
For 2g of TlOH dissolved in water to give 2 L of solution:
[TIOH(aq)] = 2/2 g/L
= 2/2 x 1/221 M
= 1/221 M
TIOH(aq) → TI+(aq) + OH-(aq)
OH-(aq) = TIOH(aq) = 1/221M
Kw = [H+] [OH-]
10-14 = [H+] [1/221]
[H+] = 221x10-14
⇒ pH = -log [H+] = -log ( 221x10-14)
= 11.65
(b) For 0.3 g of Ca(OH)2 dissolved in water to give 500 mL of solution:
Ca(OH)2 → Ca2+ + 2OH-
[Ca(OH)2] = 0.3x1000/500 = 0.6M
OH-(aq) = 2 x [Ca(OH)2(aq)] = 2 x 0.6 = 1.2M
[H+] = Kw / OH-(aq)
= 10-14/1.2 M
= 0.833 x 10-14
pH = -log(0.833 x 10-14)
= -log(8.33 x 10-13)
= (-0.902 + 13)
= 12.098
(c) For 0.3 g of NaOH dissolved in water to give 200 mL of solution:
NaOH → Na +(aq) + OH-(aq)
[NaOH] = 0.3 x 1000/200 = 1.5M
[OH-(aq)] = 1.5M
Then [H+] = 10-14 / 1.5
= 6.66 x 10-13
pH = -log ( 6.66 x 10-13)
= 12.18
(d) For 1mL of 13.6 M HCl diluted with water to give 1 L of solution:
13.6 x 1 mL = M2 x 1000 mL
(Before dilution) (after dilution)
13.6 x 10-3 = M2 x 1L
M2 = 1.36 x 10-2
[H+] = 1.36 × 10-2
pH = - log (1.36 × 10-2)
= (- 0.1335 + 2)
= 1.866 = 1.87
Popular Questions of Class 11 Chemistry
- Q:-
The mass of an electron is 9.1 × 10–31 kg. If its K.E. is 3.0 × 10–25 J, calculate its wavelength.
- Q:-
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.
- Q:-
Calculate the wavelength of an electron moving with a velocity of 2.05 × 107 ms–1.
- Q:-
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)
- Q:-
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?
- Q:-
What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30°C?
- Q:-
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
- Q:-
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?
- Q:-
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)
- Q:-
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?
Recently Viewed Questions of Class 11 Chemistry
- Q:-
Addition of HBr to propene yields 2-bromopropane, while in the presence of benzoyl peroxide, the same reaction yields 1-bromopropane. Explain and give mechanism.
- Q:-
Write the conjugate acids for the following Brönsted bases: NH–2 , NH3 and HCOO–.
- Q:-
Suggest reasons why the B-F bond lengths in BF3 (130 pm) and BF-4(143 pm) differ.
- Q:-
(i) Calculate the total number of electrons present in one mole of methane.
(ii) Find
(a) the total number and
(b) the total mass of neutrons in 7 mg of 14C. (Assume that mass of a neutron = 1.675 × 10–27 kg).(iii) Find
(a) the total number and
(b) the total mass of protons in 34 mg of NH3 at STP.Will the answer change if the temperature and pressure are chang
- Q:-
Find energy of each of the photons which
(i) correspond to light of frequency 3× 1015 Hz.
(ii) have wavelength of 0.50 Å.
- Q:-
Write bond line formulas for : Isopropyl alcohol, 2,3-Dimethyl butanal, Heptan-4- one.
- Q:-
Explain why is sodium less reactive than potassium?
- Q:-
Calculate the number of atoms in each of the following
(i) 52 moles of Ar
(ii) 52 u of He
(iii) 52 g of He.
- Q:-
Give reasons:
(i) Conc. HNO3 can be transported in aluminium container.
(ii) A mixture of dilute NaOH and aluminium pieces is used to open drain.
(iii) Graphite is used as lubricant.
(iv) Diamond is used as an abrasive.
(v) Aluminium alloys are used to make aircraft body.
(vi) Aluminium utensils should not be kept in water overnight.
(vii) Aluminium wire is used to make transmission cables.
- Q:-
The mass of an electron is 9.1 × 10–31 kg. If its K.E. is 3.0 × 10–25 J, calculate its wavelength.
- NCERT Chapter