chemistry: chapter 8

all learning objectives (8.1-8.7)

solute

evenly dispersed throughout a second substance

present in the smaller amount

solvent

“second substance”

present in the larger amount

key characteristics of a solution

solutes are evenly distributed in the solvent

components do not chemically react with each other

aqueous solutions are transparent

components do not separate upon standing

concentration can be changed

behavior of water 

high boiling point and low vapor pressure

ice has a lower density than liquid water because the molecules get further apart to make optimal hydrogen-bonding contacts 

solutions

can be solid, liquid, or gas

components do not separate over time

transparent

examples: tea, soda

colloids 

particles must be between 1nm and 100 nm

components do not separate over time

not transparent 

examples: milk in coffee or tea

suspensions

particles are larger than 1000 nm

components do separate over time

transparent when settled; not transparent when not settled

examples: muddy water or blood

unsaturated solution

when a solution does not contain the maximum amount of solute that the solvent can hold

saturated solution

when a solution contains all the solute that can possibly dissolve

what is the physical equilibrium that a saturated solution reaches? 

the rate of dissolving solute and the rate of dissolved solute reforming crystals are the same 

• can be demonstrated by a double arrow or equilibrium arrow

why do gout and kidney stones happen?

they happen when compounds exceed their solubility limits

predict the effect of temperature on the solubility of a solid solute

the solubility of solids dissolved in water increases with temperature (directly related)

predict the effect of temperature on the solubility of a gas solute

the solubility of a gas dissolved in water decreases with rises in temperature (inversely related)

predict the effect of pressure on the solubility of a gas in a liquid 

henry’s law: the solubility of a gas in a liquid is directly related to the pressure of that gas over the liquid 

strong electrolytes

ionic compounds that dissolve in water

full dissociate

non electrolytes

soluble covalent compounds that do no dissociate and do not conduct electricity

weak electrolytes

some covalent compounds that partially dissociate in water

(weak acids)

rules for writing chemical equations for solution formation 

always right H2O under or over the reaction arrow 

the products are always (aq)

weak electrolytes: double arrow; an H+ will be a byproduct

strong electrolytes: don’t forget the products’ charges

non electrolytes: reactants and products are the same, except the products have (aq) 

what does the unit Equivalent (Eq) mean?

relates the charge in a solution to the number of ions or the moles of ions present 

(the number of Eq present per mole of an ion equals the charge on that ion)

what is a %(m/v) unit?

g/dL

units for ppm and ppb

ppm: 1mg/L

ppb: 1 ug/L

dilution

allows us to get a solution with lower concentration from a solution with higher concentration

isotonic solutions 

solute: same inside and out of the cell

water: same inside and out of the cell 

no net movement of water

no effect on the cell

hypotonic solutions

solute: low outside, high inside

water: high outside, low inside

water moves into the cell to reach equilibrium

hemolysis (cell swells or bursts)

hypertonic solutions

solute: high outside, low inside

water: low outside, high inside

waters leaves the cell to reach equilibrium

crenation (cells shrivel)

which way does water move?

from an area of low solute concentration to an area of high solute concentration

physiological solutions 

0.90% (m/v) NaCl (normal saline, NS)

5% (m/v) D-glucose (dextrose) solution or D5W

osmolarity

takes into account the number of particles exerting osmotic pressure against a membrane

molarity x the number of particles in solution

passive diffusion (what molecules can passively diffuse)

moves solutes to equalize concentrations on either side of a membrane with no additional energy required

water and non polar molecules (O2, N2, CO2, steroids)

facilitated transport

does not require energy

enables small molecules and ions to pass through the cell membrane with the use of protein channels (often integral membrane proteins) a

active transport 

requires energy and the assistance of a protein channel or pump 

transports ions or small polar molecules across the cell membrane against the concentration gradient 

example: ATPase pump