Chapter 13 - Properties of Solutions

Solution

Homogeneous mixture of solute and solvent.

Solutions

________________ may be gases, liquids, or solids.

Solvent

What is doing the dissolving (usually the larger amount).

Solute

What is dissolved (typically the smaller amount).

Aqueous

_______________ solutions (aq) contain water as the solvent.

disperses

Solutions are formed when one substance _______________.

2

How many things impact solution formation?

mixing

Natural tendency towards ______________ is one thing impacting formation.

Intermolecular

______________ forces are one thing impacting formation.

spontaneously

Gases _______________ mix.

Entropy

Reflects the degree of chaos (thermodynamic quantity that measures the extent of the spreading of the molecules and their associated kinetic energies).

increase

The mixing that occurs as the solution is formed represents a/an ______________ in entropy.

3

How many kinds of intermolecular attractions are involved in solution formation?

similar

Similar intermolecular forces need ______________ energy to dissolve.

liquids and solids

Which states do the intermolecular forces impact?

(Consider the intermolecular attractions between gas molecules)

Solute-solute

Interactions between solute particles → BREAK to form solution.

These must be overcome in order for the particles to disperse through the solvent.

Solvent-solvent

Interactions between solvent particles → BREAK to form solution.

These must be overcome to make room for the solute particles in the solvent.

Solvent-solute

Interactions between solvent and solute particles → FORM solution.

These occur as particles mix.

nonpolar

Nonpolar dissolves in _______________.

polar

Polar dissolves in _____________.

polar

Ionic dissolves in _____________ .

(consider dissociation & intermolecular forces)

Solvation

Ion dipole forces/interactions between solute and solvent.

hydration

Ion dipole forces/interactions between solute and solvent, but with WATER as the solvent.

∆H(solute) + ∆H(solvent)

∆H(solution) = ____________ + ______________

intermolecular forces

∆H(solution) can be either positive or negative, depending on the __________________________.

endothermic

Breaking attractive intermolecular forces is always ________________. (solute-solute, solvent-solvent)

∆H(solute) and ∆H(solvent) are both positive.

exothermic

Forming attractive intermolecular forces is always _________________. (solute-solvent)

∆H(mix) is always negative!

negative

In general, solutions form if the ∆H(solution) is _________________.

endothermic

If ∆H(solution) is too ________________, a solution will not form.

likes dissolve likes

“Rule of Thumb” for solution formation

physical, chemical

Some solutions form by ______________ properties and some by ____________ chemical properties.

solubility

Factors affecting _______________:

1. Nature of Solute

2. Nature of Solvent

3. Temperature

4. Pressure

direct

Relationship between Intermolecular Forces and Solubility:

IF+, S+

dipole-dipole

Favorable ______________ interactions include solute-solute, solvent-solvent, and solute-solvent.

miscible

Pairs of liquids that mix in any proportions.

(polar in polar OR nonpolar in nonpolar)

immiscible

Pairs of liquids that do not mix significantly.

(nonpolar in polar OR polar in nonpolar)

hydrogen bonding

Compounds with possibility of _______________________ usually dissolve better in water.

similar

Substances with _________________ intermolecular forces tend to be soluble in one another.

gas

Which state’s solubility does pressure impact the most?

direct

Relationship between gas pressure and solubility:

P+, S+

(more molecules of the gas get closer to the surface of the solution → higher probability of gas molecule striking surface and entering solution)

Henry’s Law

Idea that the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the solution.

S(g) = kP(g)

[Solubility of gas (mol/L) = constant (mol/L-atm) x partial pressure (atm)

indirect

Relationship between temperature and solubility (GAS in a liquid):

T+, S-

(gas particles gain sufficient energy from the heat to escape the solution → thermal pollution!)

direct

Relationship between temperature and solubility (SOLID in a liquid):

T+, S+

(energy given to solid by heat helps break it down to dissolve in the solvent)

dilute

Solution that has a relatively small concentration of solute.

concentrated

Solution that has a relatively high concentration of solute.

Mass percentage

One of the easiest ways to express concentration:

(Mass of component in soln / total mass of soln)

x 100%

Mole fraction

Concentrations expressed (X) based on the number of moles of one or more components (has NO units):

X = moles of component / total moles of all components

Molarity

M = moles of solute / liters of solution

(NOTE: M will change with a change in temperature → as the solution volume increases or decreases)

0.17 M

Solid B(ClO)₃ is added to distilled water to produce a solution in which the concentration of chlorate, [ClO₃⁻], is 0.5 M. What is the concentration of the boron ion, [B³⁺], in this solution?

20 g

Approximately what mass of NiSO₄ .. 5H₂O (280 g/mol) is required to prepare 300 mL of 0.2 M nickel (II) sulfate solution?

0.075 mol

How many moles of K⁺ ions are in 100mL of 0.25 M K₃PO₃ (aq)?