General Chemistry: Chapter 5

soluble salts

group 1 metal cations

NO₃^-

ClO₄^-

C₂H₃O₂^-

NH₄⁺

insoluble salts

Ag⁺

Pb²⁺

Hg²⁺

OH^-

S2^-

CO₃^-2

PO₄^3-

(insoluble/soluble) trumps (insoluble/soluble)

soluble trumps insoluble

what is an electrolyte

substance that has a natural positive or negative electrical charge when dissolved in water

strong electrolytes

dissociate fully —> soluble ionic compounds, strong acids & strong bases

weak electrolytes

incompletely dissociate —> weak acid, weak bases

non electrolytes

do NOT dissociate —> molecular compounds that aren’t acidic or basic

how is solubility impacted:

solids at increased temperatures

gases at increased pressures

gases at increased temperatures

solids at increased temperatures: increased solubility

gases at increased pressures: increased solubility

gases at increased temperatures: decreased solubility

spectrophotometry

measures how much chemical substance absorbs light by measuring a beam’s intensity

Beer’s law

A = Elc

A = absorbance

E = molar absorptivity

l = path length

c = concentration of the solution

heterogeneous mixture vs homogenous mixture

hetero: non-uniform (salad)

homo: uniform (air)

Molarity vs molality

M = moles of solute / liters of solution

m = moles of solute / kg of solvent

diluted vs concentrated vs saturated solutions

diluted: small solute

concentrated: large solute

saturated: maximum solute

normality formula

Normality = (number of equivalents)(Molarity)

mole fraction formula

mole fraction = moles of solute / total moles in solution

colligative properties

depend on concentration solution/ions (ex: BP elevation, vapor-pressure depression, freezing point depression, osmotic pressure)

when vapor pressure increases, BP (increases/decreases)

vapor pressure increases, BP decreases (easier to boil)

Raoult’s law

to calculate new vapor pressure

P_{after solute} = solvent mole fraction x vapor pressure of solvent

change in BP temperature formula

T_b = k_bim

k_b = solvent BP elevation constant

i = solute Van Hoff factor

m = molality

change in freezing point

T_f = -k_fim

k_f = solvent FP depression constant

i = solute Van Hoff factor

m = molality

osmotic pressure

OP = iMRT

i = solute Van Hoff factor

M = Molarity

R = gas constant

T = temperature in K

non-colligative properties & examples

depend on solute or solvent’s identity

• surface tension

• viscosity, solubility, color & density

cohesive vs adhesive

cohesive: attractive forces of the same substance

adhesive: attractive forces of different substances

net ionic equation

only ions/substances that directly make the reaction happen