Pure Substance:
A substance made up of only one type of particle. Eg.) Gold, any element
Mixture:
A substance made up of more than one type of particle, individual components keep
their properties. Can be separated by physical means like evaporation. Eg.) Sand in water
Heterogenous mixture:
A mixture where the different substances are distinguishable, particles are not evenly
distributed. Eg.) Salt and pepper
Homogenous mixture:
A mixture where the different particles are evenly distributed, to the naked eye, there
appears to be only one type of particle, cannot be easily separated. Eg.) milk
Suspensions:
Mixtures where the particles of one substance are dispersed throughout a liquid or gas.
Eventually, if left alone, the particles will settle. Eg.) sand in water
Tyndall Effect:
Light reflecting off a solid particle in a suspension instead of passing through it. Eg.)
Crystals in water reflecting light
Emulsion:
A suspension of 2 or more liquids. Eg.) mayonnaise
Solutions:
A homogenous mixture of 2 or more substances, consists of a solute and a solvent. Eg.)
salt water
Colloids:
A mixture where insoluble particles are dispersed and suspended in another substance.
Does not settle Eg.) silt
Gel:
Colloidal suspension of a solid dispersed in a liquid, does not settle. Eg) gelatin
Solvent:
The substance that does the dissolving Eg.) water in salt water
Solute:
The substance that is dissolved. Eg.) salt in salt water
Soluble:
A substance that can be dissolved in another substance. Eg.) salt in water
Insoluble:
A substance that cannot be dissolved in another substance. Eg.) oil in water
Miscible:
Liquids that can dissolve in each other. Eg.) Alcohol and water
Immiscible:
Liquids that cannot be dissolved in each other. Eg.) Oil and water
Alloys:
Molten metal mixtures (that have cooled). Eg.) brass
Amalgam:
A alloy where one of the metals is mercury. Eg.) dental filling
Tincture:
A solution where the solvent is alcohol. Eg.) White willow bark and ethanol
Effervescence:
The gas that escapes from a solution. Eg.) Carbon dioxide released from chipped
limestone.
Aqueous:
Solution where water is the solvent. Eg.) Salt in water
Colloidal dispersions:
Mixtures that appear to be homogenous, but tiny droplets of solute are suspended in a
solvent because the electrostatic attractions are minimal. Eg.) paint, blended food
True Solutions vs Colloidal Dispersions:
- Colloidal dispersions are heterogeneous, there are minimal attractions that make them
look like true solutions
- An interaction between the solute and the solvent and solute it is a true solution
- There are 9 possibilities of solutes and solvents that can make up a solution because
there are 3 states of matter.
- Written as solute - solvent. Eg.) salt water (s)-(l), solid-liquid
- Usually liquid or solid in a gas is a colloidal dispersion
Solubility and Polarity :
- Polar bonds are bonds between atoms of different electronegativity, greater the
difference higher the polarity
- Non-polar bonds are bonds where the electrons are shared equally, atoms have the
same electronegativity
- *all Hydrogen and Carbon bonds are nonpolar*
- Add up vectors to determine if a molecule is polar, some molecules contain polar bonds,
but are nonpolar due to their shape Eg.) carbon tetrafluoride
- “Like dissolves like” ⇒ polar substances only dissolve in polar substances, non-polar
substances dissolve in polar substance (there are exceptions to this)
- Ionic compounds can dissolve in polar substance as ionic compounds are charged and
polar compounds are “charged”
- Van der Waal forces: attractive forces between molecules. Bigger more polar molecules
can attract other molecules easier/better.
- Hydrogen bond: an electromagnetic attraction between a hydrogen atom in a polar
molecule and an atom from another (polar) molecule.
- Dipole-dipole forces: interactions between molecules with dipoles, only found in polar
molecules.
- Only covalent compounds can be polar/non-polar, ionic are charged
- Induced dipole - when a charged atom or molecule is brought close to a molecule
making the electrons move disproportionately to one side
Dissolving
Steps of dissolving:
1. Solvent (usually liquid) particles must move apart to make room for solute particles, this
process requires energy to overcome forces of attraction - endothermic
2. The solute particles must separate from other solute particles. This requires energy as
well - endothermic (this is lattice energy - energy required to separate the molecules or
ions in a solid crystal)
3. Solute particles move between the solvent particles and the forces of attraction between
the solute and solvent take hold and particles snap into place, move closer - exothermic
(heat of hydration is the amount of heat energy released)
- Heat of solus: Heat of solution, how much overall energy is released (exothermic) or
absorbed (endothermic)
- If net energy is an intake it’s endothermic, if net energy is released it’s exothermic
- More released = hot pack, more taken = cold pack
- Ionic substances:
- Conduct electricity when dissolved
- Dissociate when they dissolve, separate into their ions, salt turns to a sodium and
a chloride ion NaCl ⇒ Na+(aq) + Cl-(aq)
- Covalent substances:
- All covalent substances dissolve as whole substance (do not dissociate),
therefore they do not conduct electricity
- Glucose ⇒ Glucose (aq)
Factors that affect rate of dissolving:
1. Temperature:
a. Higher temperature = higher rate of dissolving, increase in kinetic energy
increases the amount of collisions meaning faster dissolving. IMFs break quicker,
can mix easier/faster
2. Particle size:
a. Increased surface area = increase in dissolving rate as less solute is exposed to
the solvent
3. Agitation:
a. Moves particles around exposing them more
4. Nature of solute:
a. Some solutes dissolve easier than others because of their chemical makeup
5. Pressure
a. Increased pressure increases the amount of gas being dissolved in a liquid
b. *applies to gas in liquid only*
Solutions:
- 3 types of solutions: unsaturated, saturated, and supersaturated
- Unsaturated solutions are solutions that can hold more solute at a particular
temperature in a certain volume
- Saturated solutions are solutions that contain the maximum amount of solute for
a certain amount of solvent at a certain temperature
- Supersaturated solutions are solutions that contain more solute than it normally
can at a certain temperature, these are very unstable, adding one more crystal
will cause much more solute precipitate to form
- Usually made by heating a solution, putting more solute in, and allowing it
to cool
Solubility:
- The maximum amount of solute that can dissolve in a certain amount of solvent under
certain conditions
- solute/solvent, g/100g, g/100ml, g/L
- Use cross multiplication to solve, basically a conversion
- 1/3 = 2/6
- Read booklet/handout for math examples
How Soap Works:
- Soap has a nonpolar tail and a polar head (like a phospholipid), non-polar end is soluble
in nonpolar materials (like grease or oil) and the head is soluble in polar substances like
water
- When soapy water comes into contact with, for example, grease on a sweater, the
nonpolar tail dissolves into the grease and the head remains dissolved in water, with
some agitation the grease can be loosened and broken into tiny goblets which remain
suspended in the solution cleaning the sweater
Solubility Curve:
- A solubility curve shows how much solute will dissolve in a given amount of solvent over
a range of temperature
- Gases decrease in solubility with an increase in temperature
- Solids increase in solubility with an increase in temperature
- Look at booklet for math