Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
NTA Abhyas JEE Main2020ChemistryThermodynamics (C)Practice

Diamonds are formed from graphite under high pressure in coal mines. Calculate the equilibrium pressure (in atm) at which graphite is converted to diamonds at 25 o C (assumed constant) given densities of ρ graphite = 2 g / cc & ρ diamond = 3 g / cc Δ G f o for diamonds is 3 kJ m - 1 from graphite

Correct answer

15001

Step-by-step solution

Differential equation of free energy dG = VdP - SdT at constant temp. with change in allotropic modification there is a change in molar volume ∴ d Δ G = Δ V dP . Δ V = M Diamond ρ Diamond - M graphite ρ graphite = 1 2 3 - 1 2 2 Δ V = - 2 cm 3 / mole = - 2 × 1 0 - 6 m 3 mole -1 ∫ d Δ G Δ G f o at 2 9 8 K, 1 atm Δ G f o at 2 9 8 K, p atm = 0 = - 2 × 1 0 - 6 m 3 mole - 1 ∫ dP P = 1 atm P = p atm Because at equilibrium when diamonds are formed

Practice Thermodynamics (C) on Quantrex Academy →

More from Thermodynamics (C)

An ideal gas ( 0.5 mol), initially at 2 bar pressure, is compressed at a constant temperature of 600 K in two steps: first, against a constant external pressure of P bar ( 2 < P < 2026List-I contains various physical/chemical processes, and List-II contains combinations of changes in enthalpy ( H ) and entropy ( S ). Match each entry in List-I to the appropriate 2026Consider the reaction 2 H ₂ S (g) + 3 O ₂(g) 2 H ₂ O (l) + 2 SO ₂(g) The magnitude of enthalpy change for the reaction in kJ mol ⁻¹ is ________. (Nearest integer) Given: _fH^ ( H ₂ 2026Match List - I with List - II. Given V₁ and V₂ are initial and final volumes respectively. List - I (Isothermal process) List - II (Expression) A. Reversible expansion I. q = 0 B. 2026Arrange the following isothermal processes in order of the magnitude of the work ( p - V ) involved between states 1 and 2 . A. Expansion in single stage w_A B. Expansion in multi 2026Consider the reaction X Y at 300 K. If H^ and K are 28.40 kJ mol ⁻¹ and 1.8 10⁻⁷ at the same temperature, then the magnitude of S^ for the reaction in J K ⁻¹ mol ⁻¹ is _______. (Ne 2026Consider the following data for the reaction X₂(g) + Y₂(g) 2XY(g) at 600 K . The _r G^ (in kJ mol ⁻¹ ) for the reaction is : Compound _f H^ _ 600K (kJ mol ⁻¹ ) S^ _ 600K (J mol ⁻¹ 2026The correct order of molar heat capacities measured at 298 K and 1 bar is : 2026 Full Thermodynamics (C) list All NTA Abhyas JEE Main PYQs