6.1 Properties of Acids and Bases Flashcards
What are acids and what are bases?
What is acid is HI?
Hydroiodic acid (monoprotic) STRONG
What acid is HBr?
Hydrobromic Acid (monoprotic) STRONG
What acid is HCl?
Hydrochloric Acid (monoprotic) STRONG
What acid is H2SO4?
Sulphuric Acid (diprotic) STRONG
What acid is HNO3?
Nitric Acid (monoprotic) STRONG
What acid is H2SO3?
Sulphurous acid WEAK
What acid is H3PO4?
Phosphoric Acid WEAK
What acid is HNO2?
Nitrous Acid WEAK
What acid is CH3COOH?
Acetic Acid (ethanoic acid) WEAK
What acid is HF?
Hydrofluoric Acid WEAK
What acid is H(Cit)3?
(C₆H₈O₇ or HOC(CH₂CO₂H)₂)
Citric Acid WEAK
3 common properties of acids
sour, turns blue litmus red, reacts with reactive metals
Acid + reactive metal →
hydrogen gas + salt
Acid + carbonate →
CO2 + salt + water
Acid + metal oxide →
salt + water
Acid + metal hydroxide →
salt + water
what is an acid
any solution that forms H+ ions in water
What is an inorganic acid?
a compound containing hydrogen and non-metallic atoms or their groups
what is an organic acid?
any compound with directly connected C&H
organic vs inorganic base
organic if a base includes C,
inorganic (everything else) includes OH or O2- or metallic atoms
nomenclature for monoatomic ion in acid
hydro-[X]-ic acid
nomenclature for polyatomic ion in acid ending in -ate
-ic acid
nomenclature for polyatomic ion in acid ending in -ite
-ous acid
what is a base
any substance that forms OH- ions in water
3 common properties of bases
soapy feel (aqueous), bitter, turns litmus paper blue
neutralisation reaction
acid + base –> salt + water
usually EXOTHERMIC
explain neutralisation of ant bites
has formic acid HCOOH, neutralised with baking soda NaHCO3
explain neutralisation of indigestion
HCl neutralised with antacid tablets Mg(OH)2
NOTE all enthalpy reactions will release…
heat loss into environment/equipment
alkalis are…
soluble bases
juices vs cleaners
acidic vs basic
what is pH
“power of hydrogen” measuring acidity/alkalinity by concentration of hydrogen (or hydronium) ions on logarithmic scale from 0-14
hydronium
H3O+ (water with added hydrogen)
what are indicators
tools measuring pH using two different coloured chemical species
indicator equilibrium
HIn + H2O ⇌ In- + H3O+
HIn molecule = protonated form of indicator (more acidic)
In- ion = unprotonated form of indicator (more basic)
HIn and In- are two different colours
methyl orange range and colours
3.1 - 4.4, orange to yellow
phenolphthalein range and colours
8.2 - 10, red to colourless
bromothymol blue range and colours
6.0 - 7.6, blue to yellow
4 natural indicators
anthocyanin, cochineal, litmus, hydrangeas
concentration of H+ at 25C
[H3O+] = 1 x 10-7 mol L-1
then [H+] = 1 x 10-7
Equilibrium constant for water self ionisation
Kw = [H3O-] x [H+] = x2
= 1 x 10-14 mol L-2 at 25oC
2 logarithmic equations for pH
pH = -log10[H+]
[H+] = 10^ (-pH)
3 acid/base conjugate pair equations
pH + pOH = 14
Ka x Kb = Kw = 1.0 x 10-14 at 25oC
Kw = [H3O+] x [OH-]
(LCP) increase temperature → equilibrium moves to lower temperature by absorbing extra heat →
favours forward reaction → equilibrium shifts right → more hydroxide ions formed → Kw value increases
2 equations involving pOH
pOH = -log[OH-]
[OH-] = 10^ -pOH
acids sting/burn, while alkalines feel…
slippery
strong acids ionise…
completely
concentration vs strength
conc. = number of ions/molecules mol/L;
strength = degree/percentage of ionised molecules
when are acids/bases electrolytes
soluble acids
aqueous bases
oxides of the first 2 periodic groups are
basic, e.g. KOH, NaOH…
4 steps making red cabbage indicator
1) chop cabbage into small pieces
2) boil until coloured
3) strain and cool at room temp
4) decant
3 steps: how to test red cabbage
1) prepare test tubes of various pH
2) add indicator
3) record differentiations across pH
weak acid neutralisation reactions use what arrow?
equilibrium arrow
