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What are acids and bases? - Coggle Diagram
What are acids and bases?
Properties
Acid
sour taste
turns blue litmus paper red
#
conduct electricity in solution
corrosive
electrolytes in solution (ions)
ionise
form donatable proton
neutralise bases
#
Base
bitter taste
soapy feel in aq solution
conduct electricity in solution
turns red litmus paper blue
#
corrosive
electrolytes in solution
often accept a proton
neutralises acids
Reactions of Acids
Acid + base
Neutralisation
acid + base -> salt + water
Example
applications
everyday life
antacids
reduce acid levels in stomach
contain magnesium hydroxide bases
baking soda (sodium hydrogen carbonate)
combines with acidic ingredients
dough rises
toothpaste
alkaline
neutralise acids in mouth
remove food particles
produce acid when break down
fluoride
strengthens tooth enamel
replace OH-
resistant to acids
tooth enamel
basic
easily decayed with acid
industrial
agriculture
ability for plants to take up nutrients
affected by acid/base
some plants grow better in acidic or basic soil
fertiliers
made from neutralisation
sulfuric acid + ammonia gas
waste water
too acidic/alkaline
damage environment
too alkaline
sulfuric acid, hydrochloric acid, nitric acid
too acidic
calcium oxide
industry spills
acid spills
sodium carbonate, sodium hydrogen carbonate
base spills
dilute sulfuric/hydrochloric acid
often reversible
acid + carbonate
acid + carbonate -> salt + water + carbon dioxide
example
Acid + metal
acid + metal -> salt + hydrogen gas
example
magnesium displaces hydrogen ions
form hydrogen gas
unreactive metals
normally do not react with acids
acid - strong reducing agent
reaction may occur
displacement reaction
Definitions
#
Acid
Substance that in solution produces H+ ions
Examples
Base
substance that in solution produces OH-
substance that contains the OH- or O2-
Examples
amphoteric
#
substance
act either as a base or acid
water
Change in understanding
Arrhenius Theory
acid
release H+ ions in solution
examples
base
release OH- ions in solution
examples
Svante Arrhenius
late 19th century
limitations
cannot account for
why metal oxides/carbonates produce bases
some salts produce basic or acidic solution
acid/base relationship
not consider role of solvent
only works in aqueous solutions
pure HCl not acid
ammonia not base
neutralisation reaction
H+ + OH- -> H2O
Brønsted-Lowry Theory - proton (H+)
acids
proton donor
examples
conjugate base
base
proton acceptor
examples
conjugate acid
limitations
not explain
reactions between acid/base oxides
takes place even without a solvent
nature of amphoteric substances
that do not have protons
nature acid/base involving exchange of protons
when solvent cannot
donate/accept H+ ions
broader than Arrhenius
neutralisation
conjugate pairs
foward reaction
Water - base
accepting proton
HA - acid
donating proton
reverse reaction
H3O+ - acid
A- - base
Base1 + Acid1 -> base2 + acid 2
Lewis' definition
acid
electron pair acceptor
any atom, molecule, ion
accept proton
examples
base
electron pair donor
any atom, molecule, ion
capable of donating proton
examples
broader than Brønsted-Lowry
does not require proton or solvent
explains why BF3 reacts with ammonia
ammonia = base
BF3= acid
accepts N lone pairs
neutralisation
formation of co-ordinate covalent bond
between acid + base
Antoine Lavoisier - Oxygen theory
non-metal compounds contain oxygen
act as acids
when dissolved in water
limitations
did not account for
why metal oxides produced bases
some acids - stronger than others
Humphry Davy - Hydrogen theory
whilst performing electrolysis
on solution containing HCl
found that no oxygen present
acids
substances that contain hydrogen
gives acid its properties
limitations
did not account for
why compounds with hydrogen
are not acidic
some acids strogner than others
neutralisation reactions
why metal oxides produced bases
Indicators
change colour in presence of acid/base
via equilibrium reaction
reversible reactions
acid
Increase concentration H+
equilibrium counteract increase
shift to left
favour red solution
base
decrease concentration H+
shift to right
favour blue solution