Entropy

Physics ⇒ Heat and Thermodynamics

Entropy starts at 11 and continues till grade 12. QuestionsToday has an evolving set of questions to continuously challenge students so that their knowledge grows in Entropy. How you perform is determined by your score and the time you take. When you play a quiz, your answers are evaluated in concept instead of actual words and definitions used.

See sample questions for grade 12

A block of ice melts at 0℃ by absorbing 334 J of heat. What is the change in entropy? (Latent heat of fusion = 334 J/g, mass = 1 g)

A gas is compressed isothermally and reversibly from 5 L to 2 L at 300 K. Calculate the change in entropy for 1 mole of gas. (R = 8.314 J/mol·K)

A system absorbs 1000 J of heat at 400 K. What is the change in entropy?

Calculate the change in entropy when 500 J of heat is absorbed reversibly by a system at 250 K.

Calculate the entropy change when 2 moles of an ideal gas expand isothermally and reversibly from 10 L to 20 L at 300 K. (R = 8.314 J/mol·K)

Describe the significance of entropy in the context of heat engines.

Describe what happens to the entropy of the surroundings when a system undergoes an exothermic reaction.

Explain the relationship between entropy and the direction of time (the arrow of time).

Explain why entropy increases when a solid changes to a liquid.

Explain why entropy is considered a state function.

If the entropy change of a system is -5 J/K and the entropy change of the surroundings is +8 J/K, what is the total entropy change of the universe?

State the Second Law of Thermodynamics in terms of entropy.

A 1.5 mol sample of an ideal gas is compressed adiabatically and reversibly from 10.0 L to 4.0 L. What is the change in entropy of the gas?

A 2.0 mol sample of an ideal gas undergoes a reversible isothermal expansion at 350 K from 5.0 L to 15.0 L. Calculate the change in entropy of the gas. (R = 8.314 J/mol·K)

A chemical reaction occurs in an isolated system and results in a decrease in the system's entropy. What must be true about the entropy change of the surroundings for the process to be spontaneous?

A metal block at 500 K is placed in contact with a large reservoir at 300 K. If the block loses 1200 J of heat, calculate the total change in entropy of the universe.

Derive the expression for the change in entropy when a substance is heated from temperature T₁ to T₂ at constant pressure, given its molar heat capacity at constant pressure is C_p.

Explain, using the concept of microstates, why the entropy of a gas is much higher than that of a solid at the same temperature.