Compare the solubility and thermal stability of the following compounds of the alkali metals with those of the alkaline earth metals.
(a) Nitrates (b) Carbonates (c) Sulphates.
(i) Nitrates
Thermal stability
Nitrates of alkali metals, except LiNO3, decompose on strong heating to form nitrites.
2KNO3 (s) → 2KNO2(s) +O2(g)
LiNO3, on decomposition, gives oxide.
2LiNO3(s) Li2O(s) + 2 NO2(g) + O2(g)
Similar to lithium nitrate, alkaline earth metal nitrates also decompose to give oxides.
2Ca(NO3)(s) 2CaO(s) + 4 NO2(g) + O2(g)
As we move down group 1 and group 2, the thermal stability of nitrate increases.
Solubility
Nitrates of both group 1 and group 2 metals are soluble in water.
(ii) Carbonates
Thermal stability
The carbonates of alkali metals are stable towards heat. However, carbonate of lithium, when heated, decomposes to form lithium oxide. The carbonates of alkaline earth metals also decompose on heating to form oxide and carbon dioxide.
Solubility
Carbonates of alkali metals are soluble in water with the exception of Li2CO3. Also, the solubility increases as we move down the group. Carbonates of alkaline earth metals are insoluble in water.
(iii) Sulphates
Thermal stability
Sulphates of both group 1 and group 2 metals are stable towards heat.
Solubility
Sulphates of alkali metals are soluble in water. However, sulphates of alkaline earth metals show varied trends.
BeSO4 Fairly soluble
MgSO4 Soluble
CaSO4 Sparingly soluble
SrSO4 Insoluble
BaSO4 Insoluble
In other words, while moving down the alkaline earth metals, the solubility of their sulphates decreases.
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?
Balance the following equations in basic medium by ion-electron method and oxidation number methods and identify the oxidising agent and the reducing agent.
(a) P4(s) + OH – (aq) → PH3(g) + HPO2 – (aq)
(b) N2H4(l) + ClO3 – (aq) → NO(g) + Cl–(g)
(c) Cl2O7 (g) + H2O2(aq) → ClO – 2(aq) + O2(g) + H + (aq)
What do you understand by isoelectronic species? Name a species that will be isoelectronic with each of the following atoms or ions.
(i) F–
(ii) Ar
(iii) Mg2+
(iv) Rb+
The pH of a sample of vinegar is 3.76. Calculate the concentration of hydrogen ion in it.
Calculate the molarity of a solution of ethanol in water in which the mole fraction of ethanol is 0.040 (assume the density of water to be one).
A sample of drinking water was found to be severely contaminated with chloroform, CHCl3, supposed to be carcinogenic in nature. The level of contamination was 15 ppm (by mass).
(i) Express this in percent by mass.
(ii) Determine the molality of chloroform in the water sample.
In terms of period and group where would you locate the element with Z =114?
Which of the following reactions will get affected by increasing the pressure?
Also, mention whether change will cause the reaction to go into forward or backward direction.
(i) COCl2 (g) ↔ CO (g) + Cl2 (g)
(ii) CH4 (g) + 2S2 (g) ↔ CS2 (g) + 2H2S (g)
(iii) CO2 (g) + C (s) ↔ 2CO (g)
(iv) 2H2 (g) + CO (g) ↔ CH3OH (g)
(v) CaCO3 (s) ↔ CaO (s) + CO2 (g)
(vi) 4 NH3 (g) + 5O2 (g) ↔ 4NO (g) + 6H2O(g)
The reaction:
CH3CH2I + KOH(aq) → CH3CH2OH + KI
is classified as :
(a) electrophilic substitution
(b) nucleophilic substitution
(c) elimination
(d) addition
Write reactions to justify amphoteric nature of aluminium.
Explain the principle of paper chromatography.
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Alkaline qus 32 ka ans
Ans, Carbonete is tharmally most stable