Chlorine is used to purify drinking water. Excess of chlorine is harmful. The excess of chlorine is removed by treating with sulphur dioxide. Present a balanced equation for this redox change taking place in water.
The given redox reaction can be represented as:
Cl2(s) + SO2(aq) + H2O(l) → Cl-(aq) + SO2-4(aq)
The oxidation half reaction is:
S+4 O2(aq) → S+6O2-4(aq)
The oxidation number is balanced by adding two electrons as:
SO2(aq) → SO2-4(aq) + 2e-
The charge is balanced by adding 4H+ ions as:
SO2(aq) → SO2-4(aq) + 4H+(aq) + 2e-
The O atoms and H+ ions are balanced by adding 2H2O molecules as:
SO2(aq) + 2 H2O(l) → SO2-4(aq) + 4H+(aq) + 2e- ..........(i)
The reduction half reaction is: The chlorine atoms are balanced as:
Cl2(s) → Cl-(aq)
The oxidation number is balanced by adding electrons
Cl2(s) + 2e- → 2 Cl-(aq) ............(ii)
The balanced chemical equation can be obtained by adding equation (i) and (ii) as:
Cl2(s) + SO2(aq) + 2 H2O(l) → 2 Cl-(aq) + SO2-4(aq) + 4H+(aq)
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 meant by the term bond order? Calculate the bond order of: N2, O2,O2+,and O2-.
What is the difference between distillation, distillation under reduced pressure and steam distillation ?
How would you explain the fact that the first ionization enthalpy of sodium is lower than that of magnesium but its second ionization enthalpy is higher than that of magnesium?
Calculate the degree of ionization of 0.05M acetic acid if its pKa value is 4.74.
How is the degree of dissociation affected when its solution also contains (a) 0.01 M (b) 0.1 M in HCl?
Nitrogen laser produces a radiation at a wavelength of 337.1 nm. If the number of photons emitted is 5.6 × 1024, calculate the power of this laser.
Considering x-axis as the internuclear axis which out of the following will not form a sigma bond and why?
(a) 1s and 1s
(b) 1s and 2px
(c) 2py and 2py
(d) 1s and 2s.
What causes the temporary and permanent hardness of water?
Use molecular orbital theory to explain why the Be2 molecule does not exist.
How does H2O2 behave as a bleaching agent?
One mole of H2O and one mole of CO are taken in 10 L vessel and heated to 725 K. At equilibrium 40% of water (by mass) reacts with CO according to the equation,
H2O (g) + CO (g) ↔ H2 (g) + CO2 (g)
Calculate the equilibrium constant for the reaction.