EXAM 2 Flashcards
(27 cards)
What is osmosis?
Spontaneous flow of solvent through semi-permeable membrane from low solute concentration to high solute concentration
The solute does not move in a semi-permeable membrane, and equilibrium is achieved when water molecules move at equal rates on both sides.
In osmosis, what happens to water molecules in higher concentration?
Water molecules move at a slower rate due to more solute-solvent interactions
This is in contrast to lower concentration where water molecules move faster.
What are colligative properties?
Properties of a solution that depend on the quantity of particles of solute present, not the identity of the solute
Examples include vapor pressure lowering, freezing point depression, and boiling point elevation.
What is osmotic pressure?
Amount of pressure exerted to stop the flow of solvent across a semi-permeable membrane
It is calculated using the formula π=iMRT.
What does the Van’t Hoff factor (i) account for?
The number of solute particles dissolved for both electrolytes and non-electrolytes
For electrolytes, i > 1 due to dissociation, while for non-electrolytes, i = 1.
What is vapor pressure lowering?
Decrease in the vapor pressure of a solution relative to the pure solvent
It occurs because the addition of solute decreases the mole fraction of the solvent.
What is the Clausius Clapeyron Equation used for?
To showcase how temperature affects vapor pressure
It relates the change in vapor pressure to temperature changes.
What does the addition of solute do to the vapor pressure?
Lowers the vapor pressure of the solution
This is due to the decreased mole fraction of the solvent.
What is freezing point depression?
Decrease in the freezing point of a solution relative to the pure solvent
It is calculated using Tf,solution = Tf,solvent - ΔTf, where ΔTf = iKfm.
What happens when a solute is added to a liquid?
It disturbs the organization of particles, requiring a lower temperature to solidify
This results in freezing point depression.
What is boiling point elevation?
Increase in the boiling point of a solution relative to the pure solvent
It is calculated using Tb,solution = Tb,solvent + ΔTb, where ΔTb = iKbm.
What does Henry’s Law state?
Cg = KHPg
It relates the concentration of a gas in solution to the partial pressure of the gas above the solution.
How does pressure affect gas solubility in liquids?
Increases gas molecules’ contact with liquid molecules, leading to increased solubility
This is because more collisions occur between gas and liquid molecules.
What is the effect of temperature on gas solubility?
Increases in temperature decrease gas solubility
Higher energy allows gas molecules to escape the liquid more easily.
What factors affect reaction rates?
- Concentration
- Temperature
- Physical State
- Catalysts
- Pressure
Each of these factors influences the frequency of collisions and the energy of the molecules involved.
What is activation energy?
The necessary energy needed to break bonds when molecules collide
It determines the rate at which a reaction occurs.
How can reaction rates be expressed?
As the rate of decomposition of reactants or rate of appearance of products
This can be quantified using stoichiometry.
What is the rate law expression for a reaction?
rate = k[A]^n[B]^m
Where n and m are the reaction orders with respect to A and B, respectively.
How do you determine reaction order with respect to a reactant?
By using experimental data to keep one reactant concentration constant and comparing rates
Logarithmic properties can be applied to solve for the order.
What defines a zero-order reaction?
[At] = [A0] - kt
The concentration decreases linearly over time.
What is the half-life formula for a first-order reaction?
t1/2 = ln(2)/k
This indicates the time required for the concentration of a reactant to decrease by half.
What does the Arrhenius Equation relate?
Temperature and activation energy to the rate of a reaction
It shows that as temperature increases, k increases.
What are reaction mechanisms?
A set of elementary steps that a reaction takes to reach its products
They can involve one-step, two-step, or multi-step pathways.
What is a catalyst?
A substance that increases the rate of a reaction by lowering the activation energy
It is not consumed in the overall reaction.
