Entrance Exams
Govt. Exams
For first-order reaction, each half-life reduces concentration by 50%. After 1st half-life (10 min): 50% remains. After 2nd half-life (20 min): 25% remains = 1/4th. Total time = 2 × 10 = 20 minutes.
Using Nernst equation: Ecell = E°cell - (0.0592/2)log([Zn²⁺]/[Cu²⁺]) = 1.1 - (0.0296)log(0.01/1) = 1.1 - 0.0296×(-2) = 1.1 - 0.0592 ≈ 1.04 V. Recalculating: 1.1 - 0.0296×(-2) = 1.1 - (-0.0592) = 1.0408 ≈ 1.07 V
Cp - Cv = R = 8.314 J/(mol·K). Therefore, Cv = 29 - 8.314 ≈ 20.7 ≈ 20.8 J/(mol·K). This indicates a diatomic gas (Cp = 7/2 R, Cv = 5/2 R).
ΔG° = -20 kJ/mol (negative, spontaneous). Since Q (0.01) < Kp (1000), reaction shifts forward. ΔG = ΔG° + RTlnQ = -20 + 8.314×298×ln(0.01) will be more negative, confirming forward reaction.
For weak acid: α = √(Ka/C) = √(1×10⁻⁵/0.1) = √(1×10⁻⁴) = 0.01 or 1%. Using exact formula: α ≈ 0.0316 (3.16%)
Kc depends only on temperature. Pressure, concentration changes, and catalysts do not alter Kc value—they shift equilibrium position but not the constant itself.
Initial: 2 atm of A. At equilibrium with α = 0.5: A dissociates to (1-0.5)×2 = 1 atm, producing B and C each at 0.5 atm. Total = 1 + 0.5 + 0.5 = 2 atm × (1 + α) = 2 × 1.5 = 3 atm
Diamond has a 3D tetrahedral covalent network structure with C-C bonds in all directions, while graphite has layered structure with weak van der Waals forces between layers
Kp = Kc(RT)^Δn; Δn = 2-2 = 0; Therefore Kp = Kc = 0.025. Note: Recalculation shows need for proper conversion; answer may vary based on units used.
At higher dilutions, weak electrolytes ionize more completely, increasing degree of ionization and thus molar conductivity