Calculate the enthalpy change for the process
CCl4(g) → C(g) + 4 Cl(g)
and calculate bond enthalpy of C – Cl in CCl4(g).
ΔvapH0(CCl4) = 30.5 kJ mol–1.
ΔfH0 (CCl4) = –135.5 kJ mol–1.
ΔaH0 (C) = 715.0 kJ mol–1 , where ΔaH0 is enthalpy of atomisation
ΔaH0 (Cl2) = 242 kJ mol–1
The chemical equations implying to the given values of enthalpies are:
(i) CCl4(l) → CCL4(g) ΔvapHθ = 30.5 kJ mol-1
(ii) C(s) → C(g) ΔaHθ = 715.0 kJ mol-1
(iii) Cl2(g) → 2Cl(g) ΔaHθ = 242 kJ mol-1
(iv) C(g) + 4Cl(g) → CCl4(g) ΔfH = -135.5 kJ mol-1
Enthalpy change for the given process C(g) + 4Cl(g) → CCl4(g) can be calculated using the following algebraic calculations as:
Equation (ii) + 2 × Equation (iii) - Equation (i) - Equation (iv)
ΔH = ΔaHθ(C) + 2ΔaHθ (Cl2) - ΔvapHθ - ΔfH
= (715.0 kJ mol-1) + 2(242 kJ mol-1) - (30.5 kJ mol-1) - (-135.5 kJ mol-1)
∴ΔH = 1304 kJ mol-1
Bond enthalpy of C-Cl bond in CCl4(g) = 326 kJ mol-1
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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.
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(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)
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(b) KO2 and water
(c) Na2O and CO2
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(CN)2(g) + 2OH-(aq) → CN-(aq) + CNO-(aq) + H2O(l)
The concentration of hydrogen ion in a sample of soft drink is 3.8 × 10–3 M. what is its pH?
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Express the following in the scientific notation:
(i) 0.0048
(ii) 234,000
(iii) 8008
(iv) 500.0
(v) 6.0012
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b n = 1 l = 0 ml = 0
c n = 1 l = 1 ml = 0
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f n = 3 l = 1 ml = 0
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