acids, bases + solutions test 6

solutions

• solute dissolved in solvent

• indistinguishable (homogenous)

• dissolved particles are too small to see

homogenous

• uniform

• well mixed

• miscible

• eg; NaCl in water

heterogenous

• not uniform

• not well mixed

• immiscible

• eg; choc chip cookie

aqueous

solid / liquid / gas dissolved in water

unsaturated

more solute can be dissolved in solution

saturated

no more solute can be dissolved at current temp + pressure

supersaturated

• a solution containing more than the max solute that can be dissolved at given temp + pressure

• this is done by increasing temp —> adding solute —> decreasing temp

suspensions

• heterogenous mixture

• solute not dissolved significantly in a solute

• some particles settle over time + can be separated

• eg; RBC’s in plasma

colloids

• WEIRD LIQUIDS

• mixture of particles consisting of smaller clusters of ions + molecules

• evenly dispersed throughout the solvent + don’t settle over time

• eg; mayo, ink, milk

dissolution

• solute + solvent particles attract each other strongly enough to overcome the forces holding their own particles together

• this allows the solute to disperse throughout the solvent

solubility formula

m (solute in grams)

—————————

100g water

• most solids increase solubility as temp increases

• most gases decrease solubility as temp increases

• solubility of a substance can be graphed on a solubility curve

electrolyte

solution formed when solute dissolves to form ions

strong electrolyte

• all of the solute dissolves to form ions

• ionic compounds fully dissociate to form strong electrolytes

• strong acids fully ionise to form strong electrolytes

weak electrolyte

• some of the solute dissolves to form molecules - no ions formed

• weak acids partially ionise to form weak electrolytes

like dissolves like

• polar solvents dissolves polar molecules

• non-polar solvents dissolves non-polar molecules

precipitation reactions

• occurs between cations + anions in aqueous solutions

• combine to form an insoluble ionic solid (precipitate)

• eg; potassium carbonate + copper (II) nitrate

  full: K₂CO_3(aq) + Cu(NO₃)_2(aq) —> 2KNO_3(aq) + CuCO_3(s)

  ionic: CO₃^-2_(aq) + Cu²⁺_(aq) —> CuCO_3(s)

  observations: a colourless and blue solution is mixed together + a green precipitate if formed

concentration

amount of solute + solvent present in solution

n = c v

moles of solute = conc.(mol / L) x volume (L)

C1V1 = C2V2

initial = dilute

properties of acids

• turns litmus paper red

• corrosive

• sour

• solutions have pH <7

• solutions conduct electrical current

properties of bases

• turns litmus paper blue

• slippery

• bitter

• solutions have pH >7

• solutions conduct electrical current

strong acids

• completely ionises in water

• HCl, HNO₃, H₂SO₄

weak acids

• only partially ionises in water

• CH₃COOH, H₂CO₃, H₃PO₄

bases

• only partially ionises in water

• NH₃, metal hydroxides, metal oxides

acid reactions

Acid + Metal —> Salt + Hydrogen Gas

Acid + Metal Oxide —> Salt + Water

Acid + Metal Hydroxide —> Salt + Water

Acid + Metal Carbonate—> Salt + Water + Carbon Dioxide

Acid + Metal Hydrogen Carbonate—> Salt + Water + Carbon Dioxide

Acid + Metal Sulphite —> Salt + Water + Sulphur Dioxide

Base + Ammonium Salt —> Salt + Water + Ammonia

Base + Non-Metal Oxide —> Salt + Water

Arrhenius theory

• acids produce H⁺ ions when they dissolve in water

• bases produce OH^- ions when they dissolve in water

• doesn’t account for all acid-base behaviour

  • eg; why can HCO₃^- ions act as an acid + a base?

• can only be used when talking about aqueous solutions

Bronsted-lowry theory

• acids will donate protons (H⁺ ions)

• bases will accept protons (H⁺ ions)

beaker

conjugate acids + bases

• once a base has accepted a proton, it has the potential to donate the proton (act as a base)

• once an acid has donated a proton it has the ability to gain it back (act like a base)

indicators

• acid and base react with indicators

• changes their colours

• allows the pH of the solution to be determined

• litmus paper: red = acidic blue = basic

• universal indicator: changes colour over the whole pH scale

pH

• describes the conc of H⁺ ions in solutions

• pH = -log [H⁺]

• [H⁺] = 10^-pH

• 0 = acidic

• 7 = neutral

• 14 = basic

monoprotic acids

• can make 1H⁺ per molecule

polyprotic acids

• can make 2 or more H⁺ per molecule