Activity
Definition
Activity in chemistry refers to the effective concentration of a species in a solution. It accounts for interactions between molecules that alter their behavior compared to an ideal solution.
5 Must Know Facts For Your Next Test
- Activity is used instead of concentration when dealing with non-ideal solutions.
- The activity coefficient ($\gamma$) quantifies how much a substance's behavior deviates from ideality.
- For dilute solutions, the activity is approximately equal to the molar concentration.
- In concentrated solutions, interparticle forces cause significant deviations from ideality, affecting colligative properties.
- Activity plays a crucial role in calculating accurate values for equilibrium constants and reaction rates.
Review Questions
- Why is activity used instead of concentration for non-ideal solutions?
- What does the activity coefficient represent?
- How does the activity affect calculations of colligative properties?
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Related terms
Ideal Solution: A solution where the enthalpy of mixing is zero and components obey Raoult's Law across all compositions.
Colligative Properties: Properties that depend on the number of solute particles in a solution, not their identity.
Molar Concentration: The number of moles of solute per liter of solution, often used as an approximation for activity in dilute solutions.
