SLIDE 1 — ACTIVITY AND FUGACITY Activity and fugacity are thermodynamic concepts used to describe non-ideal behavior. Activity means effective concentration, while fugacity means effective pressure or escaping tendency. SLIDE 2 — ACTIVITY: DEFINITION Activity (aᵢ) is the effective concentration of a component in a solution. Formula: aᵢ = γᵢxᵢ Here, γᵢ = activity coefficient and xᵢ = mole fraction. For an ideal solution, γᵢ = 1, so aᵢ = xᵢ. SLIDE 3 — PRINCIPLE OF ACTIVITY In a real solution, molecules interact with each other, so actual behavior differs from ideal behavior. Activity corrects concentration for these interactions. γᵢ = aᵢ/xᵢ γ = 1 → ideal; γ > 1 → positive deviation; γ < 1 → negative deviation. Diagram: Real solution → Molecular interactions → Activity coefficient → Activity (a = γx) SLIDE 4 — ACTIVITY: EXAMPLE Given xₐ = 0.40 and γₐ = 1.2 aₐ = γₐxₐ = 1.2 × 0.40 = 0.48 Therefore, activity = 0.48. SLIDE 5 — APPLICATIONS OF ACTIVITY Activity is used in chemical equilibrium, reaction equilibrium, liquid solutions, electrolyte solutions, vapor-liquid equilibrium, and food/pharmaceutical systems. It gives more accurate results for non-ideal solutions. SLIDE 6 — FUGACITY: DEFINITION Fugacity (f) is the effective pressure of a real gas and represents its escaping tendency. Formula: f = φP Here, φ = fugacity coefficient and P = pressure. For an ideal gas, φ = 1, therefore f = P. SLIDE 7 — PRINCIPLE OF FUGACITY Real gases deviate from ideal behavior because of intermolecular forces, especially at high pressure. Fugacity corrects pressure for this non-ideal behavior. Diagram: Real gas → Molecular forces → Fugacity coefficient → Fugacity (f = φP) SLIDE 8 — FUGACITY: EXAMPLE Given P = 50 bar and φ = 0.90 f = φP = 0.90 × 50 = 45 bar Therefore, fugacity = 45 bar. SLIDE 9 — APPLICATIONS & COMPARISON Fugacity is used in natural-gas processing, petroleum industries, chemical equilibrium, vapor-liquid equilibrium, high-pressure systems, separation processes, and reactor design. Activity → effective concentration → mainly solutions → a = γx. Fugacity → effective pressure → mainly gases → f = φP. At phase equilibrium: fᵢᴸ = fᵢⱽ. SLIDE 10 — CONCLUSION Activity and fugacity help explain non-ideal thermodynamic behavior. Activity corrects concentration in real solutions, while fugacity corrects pressure in real gases. Both are important for chemical equilibrium, phase equilibrium, and industrial thermodynamics.
SLIDE 1 — ACTIVITY AND FUGACITY
Activity and fugacity are thermodynamic concepts used to describe non-ideal behavior. Activity means effective concentration, while fugacity means effective pressure or escaping tendency.
SLIDE 2 — ACTIVITY: DEFINITION
Activity (aᵢ) is the effective concentration of a component in a solution.
Formula: aᵢ = γᵢxᵢ
Here, γᵢ = activity coefficient and xᵢ = mole fraction.
For an ideal solution, γᵢ = 1, so aᵢ = xᵢ.
SLIDE 3 — PRINCIPLE OF ACTIVITY
In a real solution, molecules interact with each other, so actual behavior differs from ideal behavior. Activity corrects concentration for these interactions.
γᵢ = aᵢ/xᵢ
γ = 1 → ideal; γ > 1 → positive deviation; γ < 1 → negative deviation.
Diagram:
Real solution → Molecular interactions → Activity coefficient → Activity (a = γx)
SLIDE 4 — ACTIVITY: EXAMPLE
Given xₐ = 0.40 and γₐ = 1.2
aₐ = γₐxₐ = 1.2 × 0.40 = 0.48
Therefore, activity = 0.48.
SLIDE 5 — APPLICATIONS OF ACTIVITY
Activity is used in chemical equilibrium, reaction equilibrium, liquid solutions, electrolyte solutions, vapor-liquid equilibrium, and food/pharmaceutical systems. It gives more accurate results for non-ideal solutions.
SLIDE 6 — FUGACITY: DEFINITION
Fugacity (f) is the effective pressure of a real gas and represents its escaping tendency.
Formula: f = φP
Here, φ = fugacity coefficient and P = pressure.
For an ideal gas, φ = 1, therefore f = P.
SLIDE 7 — PRINCIPLE OF FUGACITY
Real gases deviate from ideal behavior because of intermolecular forces, especially at high pressure. Fugacity corrects pressure for this non-ideal behavior.
Diagram:
Real gas → Molecular forces → Fugacity coefficient → Fugacity (f = φP)
SLIDE 8 — FUGACITY: EXAMPLE
Given P = 50 bar and φ = 0.90
f = φP = 0.90 × 50 = 45 bar
Therefore, fugacity = 45 bar.
SLIDE 9 — APPLICATIONS & COMPARISON
Fugacity is used in natural-gas processing, petroleum industries, chemical equilibrium, vapor-liquid equilibrium, high-pressure systems, separation processes, and reactor design.
Activity → effective concentration → mainly solutions → a = γx.
Fugacity → effective pressure → mainly gases → f = φP.
At phase equilibrium: fᵢᴸ = fᵢⱽ.
SLIDE 10 — CONCLUSION
Activity and fugacity help explain non-ideal thermodynamic behavior. Activity corrects concentration in real solutions, while fugacity corrects pressure in real gases. Both are important for chemical equilibrium, phase equilibrium, and industrial thermodynamics.
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This content covers three key topics: Effective Concentration, where activity is defined and deviations are explained; Fugacity, detailing its definition and the impact of molecular forces at high pressure; and Applications and Key Takeaways, which highlight the practical uses of activity and fugacity in equilibrium and industrial contexts. Key calculations are provided to illustrate these concepts, emphasizing their relevance in understanding chemical behavior.