Studied by 2 peopleindicator
a compound that can reversibly change color depending on pH,
neutralisation
the reaction between an acid and a base producing a salt and water
Arrhenius' theory
this theory states that acids ionise in water to give H+ ions and bases ionise to produce OH- ions, when an acid is neutralized a salt & water is produced
Lewis theory
an acid accepts electron pairs and a base donates electron pairs
Bronsted-Lowry theory
defines an acid as a proton donor, and a base as a proton acceptor
amphiprotic
a species that can either accept or donate a proton
pH
a measure of the power of hydrogen in a system
weak acid
an acid that only undergoes partial ionisation in water
weak base
a base that only undergoes partial ionisation in water
strong acid
an acid that fully ionises in water
strong base
a base that fully ionises in water
solubility rules
a set of rules used to predict whether an ionic compound will be soluble or insoluble in water
alkali
a soluble base
acid dissociation constant
Ka, the ratio of the concentrations of the dissociated and undissociated acid parts
base dissociation constant
Kb, the ratio of the concentrations of the dissociated and undissociated base parts
ionisation constant of water
Kw, the ionic ratio between H3O and OH in water
buffer solution
a solution made from a weak acid and its conjugate base that neutralizes small amounts of acids or bases added to it
buffer capacity
the amount of acid or base a buffer solution can absorb without a significant change in pH, the greatest buffer capacity with a high concentration and equal concentration of weak acid & conjugate base.
amphoteric
A substance that can act as both an acid and a base, (Ex. water dissociation of acid to form hydronium ion/ dissociation of base to form hydroxide)
acidic solution
a solution in which [H3O+] > [OH-]
titration
a measured amount of a solution of unknown concentration is added to a known volume of a second solution until the reaction between them is just complete
equivalence point
the point in a titration where the amount of titrant added is enough to completely neutralise the analyte solution and number of moles of acid and base completely react
end point
the point in a titration at which an indicator changes color
primary standard
a standard solution that has a known concentration and is prepared by the chemist
secondary standard
A solution that has been prepared in a laboratory and has been titrated against a primary standard solution
hygroscopicity
the ability to absorb water from the atmosphere
analyte
the unknown concentration but known volume of the substance being analysed
titrant
the standard being titrated against
titre
the volumes of the titrant measured in the burette
conductometry
a measurement of electrolytic conductivity to monitor a progress of chemical reaction
buffer
compound that is able to resist a change in pH when small amounts of acid or base are added.
acidic buffer
a buffer solution with a pH less than 7, made from a weak acid and it's conjugate base.
basic buffer
a buffer solution with a pH greater than 7, made from a weak base and it's conjugate acid.
buffer region
The portion of a titration curve in which the concentration of an acid is approximately equal to that of its conjugate base; pH remains relatively constant through this region
conjugate pair
two substances related to each other by the donating or accepting of a single proton
making primary standard
weigh solid on electronic balance in clean beaker
dissolve solid in distilled water, pour into clean volumetric flask, rinsing to ensure all dissolved solid is in flask
add sufficient distilled water so meniscus is on calibration line
monoprotic
an acid that can donate only one proton (H+ ion) per molecule (e.g., HCl)
diprotic
acid that can donate two protons (H⁺ ions) per molecule (e.g., H2SO4)
differentiating strong & weak acids
pH probe
electrical conductivity conductometer
titration with a strong base (weak base will have higher equivalence point)
magnesium strip (strong acid will have more fizzing)
enthalpy of neutralisation
enthalpy change when one mole of water is formed in a reaction between an acid and an alkali under standard conditions
universal indicator
a mixture of indicators which show different colours in solutions of different pHs
pH range: 1-14
phenolphthalein
indicator with pH range: 8.3-10
colour change: clear to pink/purple
bromothymol blue
indicator with pH range: 6-7.6
colour change: yellow to blue
litmus
indicator with pH range: 4.5-8.3
colour change: red to blue
methyl orange
indicator with pH range: 3.1-4.4
colour change: red to yellow
conjugate base
acid - proton(H+)
conjugate acid
base + proton (H+)
Note
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