Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Thermodynamics question

2022 · 25 Jun · Shift 1 · Q17
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /JEE Main
  3. /Chemistry
  4. /Thermodynamics
  5. /2022 · 25 Jun · Shift 1 · Q17

Thermodynamics question

2022 · 25 Jun · Shift 1 · Q17

JEE MainChemistryThermodynamicsNumerical+4 / −1
The standard entropy change for the reaction 4FeFeFe(s) + 3O2O_2O2​(g) →\to→ 2Fe2O3Fe_2O_3Fe2​O3​(s) is −-− 550 J K −-− 1 at 298 K. [Given : The standard enthalpy change for the reaction is −-− 165 kJ mol −-− 1]. The temperature in K at which the reaction attains equilibrium is ‾\underline{\hspace{2cm}}​. (Nearest Integer)
Numerical answer
View written solutionFree

Correct answer: 300

  1. For equilibrium at a temperature TTT, the standard Gibbs free energy change must be zero:

ΔG∘=ΔH∘−TΔS∘=0\Delta G^\circ = \Delta H^\circ - T\Delta S^\circ = 0ΔG∘=ΔH∘−TΔS∘=0

So,

T=ΔH∘ΔS∘T = \frac{\Delta H^\circ}{\Delta S^\circ}T=ΔS∘ΔH∘​

  1. Given data:

ΔH∘=−165 kJ mol−1\Delta H^\circ = -165\,\text{kJ mol}^{-1}ΔH∘=−165kJ mol−1 ΔS∘=−550 J K−1\Delta S^\circ = -550\,\text{J K}^{-1}ΔS∘=−550J K−1

Convert enthalpy into joules:

ΔH∘=−165×103 J mol−1\Delta H^\circ = -165 \times 10^3\,\text{J mol}^{-1}ΔH∘=−165×103J mol−1

  1. Substitute into the equation:

T=−165×103−550T = \frac{-165 \times 10^3}{-550}T=−550−165×103​

T=300 KT = 300\,\text{K}T=300K

  1. Since both ΔH∘\Delta H^\circΔH∘ and ΔS∘\Delta S^\circΔS∘ are negative, the reaction is spontaneous at low temperature and attains equilibrium when:

T=300 KT = 300\,\text{K}T=300K

Hence, the required temperature is:

300\boxed{300}300​

PreviousNext

More from Thermodynamics

  • At 25 ∘ C and 1 atm pressure, the enthalpy of combustion of benzene (I) and acetylene (g) are − 3268 kJ mol − 1 and − 1300 kJ mol − 1, respectively. The change in enthalpy for the reaction 3 C2​H2​(g) → C6​H6​ (I),…2022 · MCQ
  • 2.4 g coal is burnt in a bomb calorimeter in excess of oxygen at 298 K and 1 atm pressure. The temperature of the calorimeter rises from 298 K to 300 K. The enthalpy change during…2022 · Numerical
  • For the reaction H2​F2​( g)→H2​( g)+F2​( g)ΔU=−59.6 kJ mol−1 at 27∘C. The enthalpy change for the…2022 · Numerical
  • For complete combustion of methanol CH3​OH(I) + 23​ O2​(g) → CO2​(g) + 2H2​O(I) the amount of heat produced as measured by bomb calorimeter is 726 kJ mol − 1 at 27 ∘ C. The enthalpy of combustion for the…2022 · Numerical
  • A fish swimming in water body when taken out from the water body is covered with a film of water of weight 36 g. When it is subjected to cooking at 100 ∘ C, then the internal energy for vaporization in kJ mol − 1 is ​…2022 · Numerical
  • The molar heat capacity for an ideal gas at constant pressure is 20.785 J K−1 mol−1. The change in internal energy is 5000 J upon heating it from 300 K to 500 K.…2022 · Numerical
  • A gas (Molar mass = 280  g mol−1) was burnt in excess O2​ in a constant volume calorimeter and during combustion the temperature of calorimeter increased from 298.0 K to 298.45K.…2022 · Numerical
  • Match List-I with List-II. Choose the correct answer from the options given below : Includes table2022 · MCQ