Benzene and naphthalene form an ideal solution at room temperature. For this process, the true statement(s) is (are)
For ideal solution
Hsolution = 0
Ssolution = +ve
Gsolution = – ve
Ssurrounding = 0
(As no heat exchange takes place)
When benzene and naphthalene form an ideal solution at room temperature, several thermodynamic properties can be analyzed. An ideal solution follows Raoult's law, meaning there are no net intermolecular interactions between the different components (benzene and naphthalene) beyond those in the pure liquids.
Step 1: Analyze ΔH (Enthalpy Change)
For an ideal solution, the enthalpy change of mixing is zero because there is no heat absorbed or released during the process. The intermolecular forces between like molecules (benzene-benzene and naphthalene-naphthalene) are equal to those between unlike molecules (benzene-naphthalene). Therefore, .
Step 2: Analyze ΔS_system (Entropy Change of the System)
When two substances mix to form a solution, the number of possible arrangements of molecules increases, leading to a higher disorder or randomness. This results in a positive entropy change for the system. .
Step 3: Analyze ΔG (Gibbs Free Energy Change)
The Gibbs free energy change is given by . Since and , . Thus, ΔG is negative, indicating the mixing process is spontaneous.
Step 4: Analyze ΔS_surroundings (Entropy Change of the Surroundings)
Since , no heat is exchanged with the surroundings. The entropy change of the surroundings, related to heat transfer by , is therefore zero. .
Final Answer: The true statements are:
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- is positive
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Ideal Solution (Topic 378): A solution that obeys Raoult's law over the entire range of concentration. The vapor pressure of each component is given by , and there is no volume change or enthalpy change on mixing.
Thermodynamics of Mixing:
- (for ideal solutions)
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