Compare the alkali metals and alkaline earth metals with respect to
(i) ionization enthalpy
(ii) basicity of oxides and
(iii) solubility of hydroxides.
S.No. |
Alkali metals |
Alkaline earth metals |
1 |
Ionization enthalpy: These have lowest ionization enthalpies in respective periods. This is because of their large atomic sizes. Also, they lose their only valence electron easily as they attain stable noble gas configuration after losing it. |
Ionization enthalpy: Alkaline earth metals have smaller atomic size and higher effective nuclear charge as compared to alkali metals. This causes their first ionization enthalpies to be higher than that of alkali metals. However, their second ionization enthalpy is less than the corresponding alkali metals. This is because alkali metals, after losing one electron, acquires noble gas configuration, which is very stable. |
2 |
Basicity of oxides: The oxides of alkali metals are very basic in nature. This happens due to the highly electropositive nature of alkali metals, which makes these oxides highly ionic. Hence, they readily dissociate in water to give hydroxide ions. |
Basicity of oxides: The oxides of alkaline earth metals are quite basic but not as basic as those of alkali metals. This is because alkaline earth metals are less electropositive than alkali metals. |
3 |
Solubility of hydroxides: The hydroxides of alkali metals are more soluble than those of alkaline earth metals. |
Solubility of hydroxides: The hydroxides of alkaline earth metals are less soluble than those of alkali metals. This is due to the high lattice energies of alkaline earth metals. Their higher charge densities (as compared to alkali metals) account for higher lattice energies. |
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.
Discuss the various reactions that occur in the Solvay process.
Comment on each of the following observations:
(a) The mobilities of the alkali metal ions in aqueous solution are Li+ < Na+ < K+ < Rb+ < Cs+
(b) Lithium is the only alkali metal to form a nitride directly.
(c) E° for M2+(aq) (where M = Ca, Sr or Ba) is nearly constant.
Why are lithium salts commonly hydrated and those of the other alkali metal ions usually anhydrous?
State as to why
(a) a solution of Na2CO3 is alkaline ?
(b) alkali metals are prepared by electrolysis of their fused chlorides ?
(c) sodium is found to be more useful than potassium ?
When an alkali metal dissolves in liquid ammonia the solution can acquire different colours. Explain the reasons for this type of colour change.
In what ways lithium shows similarities to magnesium in its chemical behaviour?
Why is Li2CO3 decomposed at a lower temperature whereas Na2CO3 at higher temperature?
Find the oxidation state of sodium in Na2O2.
Explain why is sodium less reactive than potassium?
How do you account for the formation of ethane during chlorination of methane?
What are hybridisation states of each carbon atom in the following compounds ?
(i) CH2=C=O,
(ii) CH3CH=CH2,
(iii) (CH3)2CO,
(iv) CH2=CHCN,
(v) C6H6
What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30°C?
Calculate the molecular mass of the following:
(i) H2O
(ii) CO2
(iii) CH4
Assign oxidation number to the underlined elements in each of the following species:
(a) NaH2PO4
(b) NaHSO4
(c) H4P2O7
(d) K2MnO4
(e) CaO2
(f) NaBH4
(g) H2S2O7
(h) KAl(SO4)2.12 H2O
What is the basic theme of organisation in the periodic table?
Explain the formation of a chemical bond.
Choose the correct answer. A thermodynamic state function is a quantity
(i) used to determine heat changes
(ii) whose value is independent of path
(iii) used to determine pressure volume work
(iv) whose value depends on temperature only.
A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased.
a) What is the initial effect of the change on vapour pressure?
b) How do rates of evaporation and condensation change initially?
c) What happens when equilibrium is restored finally and what will be the final vapour pressure?
Justify the position of hydrogen in the periodic table on the basis of its electronic configuration.
A mixture of dihydrogen and dioxygen at one bar pressure contains 20% by weight of dihydrogen. Calculate the partial pressure of dihydrogen.
What do you understand by the term “non-stoichiometric hydrides”? Do you expect this type of the hydrides to be formed by alkali metals? Justify your answer.
Write the favourable factors for the formation of ionic bond.
How would you explain the lower atomic radius of Ga as compared to Al?
For the reaction
2 A(g) + B(g) → 2D(g)
ΔU0 = –10.5 kJ and ΔS0 = –44.1 JK–1.
Calculate ΔG0 for the reaction, and predict whether the reaction may occur spontaneously.
Why is benzene extra ordinarily stable though it contains three doublebonds?
In the modern periodic table, the period indicates the value of:
(a) Atomic number
(b) Atomic mass
(c) Principal quantum number
(d) Azimuthal quantum number.
The pH of 0.1M solution of cyanic acid (HCNO) is 2.34. Calculate the ionization constant of the acid and its degree of ionization in the solution.
Explain, giving reasons, which of the following sets of quantum numbers are not possible.
a n = 0 l = 0 ml = 0
b n = 1 l = 0 ml = 0
c n = 1 l = 1 ml = 0
d n = 2 l = 1 ml = 0
e n = 3 l = 3 ml = – 3
f n = 3 l = 1 ml = 0
Explain what happens when boric acid is heated.