Zusammenfassung der Ressource
The Acidic Environment
- Indicators
- Bromothymol blue (yellow)6.2-7.6(blue)
-Methyl orange (red)3.1-4.4(yellow)
-phenolphthalein (colourless)8.3-10.0(pink)
- pH of oxides
- non-metal
oxides- acidic
- metal oxides-
basic
- amphoteric-
can be both eg.
H2O
- Le Chatelier’s Principle
- counteract
any change
in
equilbrium
- oxide production
- sulfur oxides
- volcanoes-burning of
fossil fuels - smelting
metal ores
- nitrogen oxides
- lightning- vechicles
- acid rain
- pH <5 - SO or NO in H2O
Anmerkungen:
- SO2(g) + H2O(l) -> H2SO3(aq) 2NO2(g) + H2O(l) -> HNO3(aq) + HNO2(aq)
2H2SO3(aq) + O2(g) -> 2H2SO4(aq) 2HNO2(aq) + O2(g) -> 2HNO3(aq)
- effects
- kill aquatic ecosystem
-leeches minerals needed
for plants -erodes buildings
- acids
- weak
- 1-99% ionised - CH3COOH
(ethonoic acid - C6O7H8
(citric acid)
- strong
- 100% ionised -HCl - H2SO4
- pH = -log10[H+]
- %ionisation = [H+]
divide [acid] x 100
- History
- Lavosier- acid oxygen
- Davy- replaceable hydrogen
- Arrhenius- H+ and OH-
- Bronsted and Lowry-
acid proton donor base
proton accepter
- Conjugate acid/base
- molecules related by the loss or gain of a
proton eg. H20 (acid) and H30+
(conjugate base(accepted))
- neutralisation reactions
- salt based on stronger acid/base
-strong+strong=neutral salt + H2O
- Buffer
- weak acid and
conjugate base eg.
HCO3- and CO3 2-
- used in blood, minimises pH change
- Titration
- reacting a solution of unknown
concentration with a standard
- method
Anmerkungen:
- (1) Choose indicator which has an end point suitable to equivalence point
(2) Rinse glassware with distilled water, and then with the acid/base
(3) Wash conical flask with distilled water
(4) Fill 25mL pipette with aliquot of standard solution in volumetric flask
(5) Add 3 drops of indicator to the flask
(6) Fill burette with titrant, using dropper to add the final volumes
(7) Assemble retort stand and equipment appropriately
(8) Titrate with the left hand and swirl with right. Repeat 3 times for accuracy.
- acids in food
- -flavour enhancers
-preservative
-anti-oxidant
- carbon dioxide
- high pressure- CO2 gas dissolves
- temperature - dissolving of gas is exothermic
- Acidity- acid would create more CO2 gas