Solution Chemistry Flashcards
What is moles solute?
L of solution.
What is moles of solute?
Kg of solvent.
What is an ideal solution?
• An ideal solution or ideal mixture is a
solution in which the enthalpy of
solution (ΔHsolution) is zero.
What determines the gibbs energy of mixing for ideal solution?
entropy of mixing ( ΔSsolution ).
What are the main features of an ideal solution?
- The enthalpy of mixing of two components is zero.
- The forces of attraction between solvent and solute are exactly the same as between the original solvent molecules
- The volume of the mixing is equal to zero that is, ΔV = 0.
- Obey Raoult’s law at all concentrations and temperatures
What is Rault’s law?
The vapor pressure of a solvent above a solution is
equal to the vapor pressure of the pure solvent at the same temperature scaled by the mole fraction of the solvent present.
What is the formula of Rault’s law?
P solution= χsolvent Po solvent
where Po solvent is the vapor pressure of pure solvent and χsolvent is its mole fraction in the solution.
What are non-ideal solutions?
The solutions which don’t obey
Raoult’s law at every range of
concentration and at all temperatures
are non-ideal solutions.
What are features of non-ideal solutions?
• The enthalpy of mixing of two components is not zero.
• The forces of attraction between solvent and solute are not
the same as between the original solvent molecules
• The volume of the mixing is not equal to zero that is, ΔV ≠ 0.
there will be some expansion or contraction in the dissolution of liquids.
• Do not obey Raoult’s law.
What are the types of non-ideal solution?
Solutions that show positive deviation from Rault’s law and solutions that show negative deviation from Rault’s law.
What are features of positive non-ideal solutions?
- The enthalpy of mixing is positive (endothermic).
- The solute-solvent forces of attraction is weaker than
solute-solute and solvent-solvent interaction. - The volume of mixing is positive that is, ΔV > 0 as the
volume expands on the dissolution of components A and B. - PA > χA PoA
What are features of negative non-ideal solutions?
- The enthalpy of mixing is negative (exothermic).
- The solute-solvent forces of attraction is greater than
solute-solute and solvent-solvent interaction. - The volume of mixing is negative, that is ΔV < 0, as the
volume decreases on the dissolution of components A and B. - PA < χA PoA
What is boiling point?
The boiling point is the temperature at which the vapor pressure of a liquid is equal to the external pressure.
What is freezing point?
Freezing point is reached when the chemical potential of the liquid solvent reaches that of the solid solvent (energetically equivalent). Chemical potential is the
molar Gibb’s energy that one mole of solvent is able to contribute to a mixture
What is vapor pressure?
The pressure of a vapor in thermodynamic equilibrium with its condensed phases in a closed container
What is osmotic pressure?
The osmotic pressure of a solution is the pressure difference needed to stop the flow of solvent across a semipermeable membrane.
What are colligative properties?
Colligative properties are the physical changes that result from adding solute to a solvent. Colligative Properties depend on the quantity solute particles present as well as the solvent amount, but they do NOT depend on the type of solute particles, although do depend on the type of solvent.
What is the role of solute in colligative properties?
Solute must not contribute to the
vapor pressure of the solution.
• Solute must remain suspended in
the solution even during phase
changes.
What are examples of colligative properties?
Freezing
point
depression
Boiling point
elevation
Vapor
pressure
lowering
Osmotic
Pressure
What is freezing point depression?
The freezing points of solutions are all lower than that of the pure solvent and is directly proportional to the molality of the solute.
What is the formula of freezing point depression?
ΔTf = Tf(solution) − Tf(solvent) = − Kf × m
where ΔTf is the freezing point depression, m is the solute molality, Kf is the freezing point depression constant.
What is boiling point elevation?
The boiling points of solutions are
all higher than that of the pure
solvent.
What is formula for boiling point elevation?
ΔTb= Tb(solution) − Tb (solvent) = Kb × m
where ΔTb is the boiling point elevation, m is the solute molality, Kb is the boiling point elevation constant.
What is vapor pressure lowering?
The vapor pressure of a solvent in a
solution is always lower than the
vapor pressure of the pure solvent.
