ACIDS, BASES , AND pH
description
Transcript of ACIDS, BASES , AND pH
ACIDS, ACIDS, BASES, AND pH, AND pH
2
An acid -------> H+ in waterAn acid -------> H+ in water
Arrhenius ACIDSArrhenius ACIDSArrhenius ACIDSArrhenius ACIDS
HCl(aq) ---> H+(aq) + Cl-(aq)
3
Base ---> OH- in waterBase ---> OH- in water
Arrhenius BASESArrhenius BASES
NaOH(aq) ---> NaNaOH(aq) ---> Na++(aq) + OH(aq) + OH--(aq)(aq)
NaOH is a NaOH is a strong basestrong base
Arrhenius TheoryArrhenius TheoryAcids HAcids H++
(hydrogen ions) in water
HHCl → Cl → HH++ + Cl + Cl--
Bases OHBases OH-- (hydroxide ions) (hydroxide ions) in waterNaNaOHOH → Na → Na++ + + OHOH--
D7C20
Arrhenius TheoryArrhenius Theory Substances ionize in Substances ionize in
waterwaterAcids, bases, and salts Acids, bases, and salts when dissolved in water, when dissolved in water, will will conduct electricityconduct electricity..
Called ElectrolytesCalled Electrolytes
6
The solutions conduct electricity!They are called
ELECTROLYTES
HCl, MgCl2, and NaCl are strong
electrolytes. They dissociate completely (or
nearly so) into ions.
Aqueous SolutionsAqueous SolutionsHow do we know ions are present?
7
An acid -------> HAn acid -------> H++ in water in waterAn acid -------> HAn acid -------> H++ in water in water
ACIDSACIDSACIDSACIDS
Some Some strongstrong acids areacids are
HClHCl hydrochlorichydrochloric
HH22SOSO44 sulfuricsulfuric
HClOHClO44 perchloricperchloric
HNOHNO33 nitricnitricHNOHNO33
Strong Acids will completely ionize
9
Aqueous SolutionsAqueous Solutions
weak electrolyte,like Acetic acid, ionizes only
to a small extent,
CHCH33COCO22H(aq) H(aq)
CHCH33COCO22--(aq) + H(aq) + H++(aq)(aq)
10
Weak AcidsWeak AcidsWeak AcidsWeak AcidsWeak electrolytes
CHCH33COCO22HH acetic acidacetic acid
HH22COCO33 carbonic acid carbonic acid
HH33POPO44 phosphoric acid phosphoric acid
HF hydrofluoric acidHF hydrofluoric acid
Acetic acid
11
Know the strong Know the strong acids & bases!acids & bases!
12
Aqueous SolutionsAqueous SolutionsSome compounds dissolve
in water but do not conduct electricity. They
are called
nonelectrolytes..
Examples include:Examples include:sugarsugarethanolethanolethylene glycolethylene glycol
Examples include:Examples include:sugarsugarethanolethanolethylene glycolethylene glycol
Hydrogen ions in waterHydrogen ions in water= Hydronium ions= Hydronium ions
14Ammonia, NHAmmonia, NH33
An Important Base
1515
ACID-BASE THEORIESACID-BASE THEORIESACID-BASE THEORIESACID-BASE THEORIES
• The most general theory for common aqueous acids and bases
is the BRØNSTED - LOWRY theory
•ACIDS DONATE H+ IONS
•BASES ACCEPT H+ IONS
Bronsted Bronsted BaseBase: adds : adds one one hydrogen ionhydrogen ion
Bronsted Bronsted AcidAcid: removes : removes oneone hydrogen ion hydrogen ion
Reactants Products
Chemical Reactions: New products are formed
Brønsted-Lowry TheoryBrønsted-Lowry Theory HCl + HHCl + H22O → HO → H33OO++ + Cl + Cl--
acid base C.A. C.B.acid base C.A. C.B. Conjugate acidConjugate acid –the PRODUCT –the PRODUCT
obtained after a BASE gains a obtained after a BASE gains a proton (hydrogen ion)proton (hydrogen ion)
Conjugate baseConjugate base –the PRODUCT –the PRODUCT obtained after an ACID donates a obtained after an ACID donates a proton (hydrogen ion)proton (hydrogen ion)
1919
2020
Conjugate PairsConjugate Pairs
Amphoteric Amphoteric
A substance having A substance having the ability to act as the ability to act as an acid or a basean acid or a baseor AmphoPROTICor AmphoPROTIC
Hydrogen ion = protonHydrogen ion = proton
Water is amphoproticWater is amphoprotic
It can gain and It can gain and lose a H+lose a H+
Why is Water Neutral?Why is Water Neutral?
When one water gains, When one water gains, another loses a H+another loses a H+
[H[H33O+ ] = [OH-]O+ ] = [OH-]
Brønsted-Lowry Theory Brønsted-Lowry Theory D7C20D7C20
ACIDACID: any substance that : any substance that donatesdonates a proton (hydrogen ion) a proton (hydrogen ion)
BASEBASE: any substance that : any substance that acceptsaccepts a proton (hydrogen ion)a proton (hydrogen ion)
MUST MUST occur together; Can not occur together; Can not gain unless something else losesgain unless something else loses
You PracticeYou PracticeNHNH33 + H + H22O → NHO → NH44
++ + OH + OH--
HNOHNO33 + NaOH → H + NaOH → H22O + NaNOO + NaNO33
NaHCONaHCO33 + HCl → NaCl + H + HCl → NaCl + H22COCO33
28
Acid- Base Acid- Base REACTIONSREACTIONSAcid- Base Acid- Base
REACTIONSREACTIONS
EXCHANGEEXCHANGEGas-FormingGas-FormingReactionsReactions
EXCHANGEEXCHANGE:: Precipitation Reactions Precipitation Reactions
REACTIONSREACTIONS REDOXREDOXReactionsReactions
REDOXREDOXReactionsReactions
29
ACIDSACIDSACIDSACIDSNonmetal oxides can be acids
CO2(aq) + H2O(liq)--->H2CO3(aq)
SO3(aq) + H2O(liq) ---> H2SO4(aq)
and can come from
burning coal and oil.
30
BASESBASES
Metal oxides are bases
CaO(s) + H2O(liq)
--> Ca(OH)2(aq)
CaO in water. Indicator shows solution is basic.
31
Acid-Base ReactionsAcid-Base Reactions
• sometimes called NEUTRALIZATIONS because the solution is neither acidic nor
basic at the end.
• The other product of the A-B reaction is a
SALT, MX.
HX + MOH ---> MX + H2O
Mn+ comes from base & Xn- comes from acid
This is one way to make compounds!
32
Acid-Base ReactionsAcid-Base Reactions The “driving force” is the
formation of water.
NaOH(aq) + HCl(aq) ---> NaCl(aq) + H2O(liq)
Net ionic equation
OH-(aq) + H+(aq) ---> H2O(liq)
This applies to ALL reactions of
STRONG acids and bases.