How would you explain the following observations?
(i) BeO is almost insoluble but BeSO4 in soluble in water,
(ii) BaO is soluble but BaSO4 is insoluble in water,
(iii) LiI is more soluble than KI in ethanol.
(i) BeO is almost insoluble in water and BeSO4 is soluble in water. Be2+ is a small cation with a high polarizing power and O2- is a small anion. The size compatibility of Be2+ and O2- is high. Therefore, the lattice energy released during their formation is also very high. When BeO is dissolved in water, the hydration energy of its ions is not sufficient to overcome the high lattice energy. Therefore, BeO is insoluble in water. On the other hand, SO2-4 ion is a large anion. Hence, Be2+ can easily polarize SO2-4 ions, making BeSO4 unstable. Thus, the lattice energy of BeSO4 is not very high and so it is soluble in water.
(ii) BaO is soluble in water, but BaSO4 is not. Ba2+ is a large cation and O2- is a small anion. The size compatibility of Ba2+ and O2- is not high. As a result, BaO is unstable. The lattice energy released during its formation is also not very large. It can easily be overcome by the hydration energy of the ions. Therefore, BaO is soluble in water. In BaSO4, Ba2+ and SO2-4 are both large-sized. The lattice energy released is high. Hence, it is not soluble in water.
(iii) Lil is more soluble than KI in ethanol. As a result of its small size, the lithium ion has a higher polarizing power than the potassium ion. It polarizes the electron cloud of the iodide ion to a much greater extent than the potassium ion. This causes a greater covalent character in LiI than in KI. Hence, LiI is more soluble in ethanol.
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?
Similar to electron diffraction, neutron diffraction microscope is also used for the determination of the structure of molecules. If the wavelength used here is 800 pm, calculate the characteristic velocity associated with the neutron.
Explain the important aspects of resonance with reference to the ion.
On the basis of quantum numbers, justify that the sixth period of the periodic table should have 32 elements.
Describe the method, which can be used to separate two compounds with different solubilities in a solvent S.
A large number of fish are suddenly found floating dead on a lake. There is no evidence of toxic dumping but you find an abundance of phytoplankton. Suggest a reason for the fish kill.
The species: H2O, HCO–3, HSO-4 and NH3 can act both as Brönsted acids and bases. For each case give the corresponding conjugate acid and base.
Calculate the wavelength of an electron moving with a velocity of 2.05 × 107 ms–1.
What transition in the hydrogen spectrum would have the same wavelength as the Balmer transition n = 4 to n = 2 of He+ spectrum?
Discuss the general characteristics and gradation in properties of alkaline earth metals.
Write Lewis dot symbols for atoms of the following elements: Mg, Na, B, O, N, Br.
29, ans,chhota,me how would you explain tha