Asam dan Basa

Acids and Bases

The Arrhenius-Ostwald Theory
According to this theory, an acid is a hydrogen containing compound that, when dissolve in water, produces a proton, greater than that of pure water; and a base: OH-
(berdasar teori di atas, asam adalah senyawa yang di dalam air menghasilkan proton {ion H+ } sedang basa adalah senyawa yang di dalam air menghasilkan ion OH- )

The Brønsted–Lowry Theory
According to this theory, an acid is a proton donor and a base is a proton acceptor
(dlam teori ini, asam adalah donor proton dan basa adalah penerima proton)

Weak Acids and Bases
For weak acids and bases, equations can be written to describe equilibrium conditions
(untuk asam lemah dan basa lemah dapat ditulis persamaannya untuk mendiskripsikannya ke dalam keadaan yang setimbang)


Acid–Base Equilibria
For equilibrium constant expressions, Ka is used to represent the acid ionization constant …
… and Kb is used to represent the base ionization constant
(untuk melambangkan tetapan keseimbangan digunakan:
- Ka = tetapan ionisasi asam
- Kb = tetapan ionisasi basa )

HA + H2O H+ + A– B + H2O BH+ + OH–





Strengths of Conjugate Acid–Base Pairs

Acid–Base Strength (cont’d)
Ka values are used to compare the strengths of weak acids; ­ K, ­ strength
(harga Ka digunakan untuk membandingkan kekuatan asam lemah. Jika K ­ maka kekuatannya ­ )

( untuk asam kuat, air adalah efek pengion, ketika asam kuat larut dalam air, keseluruhan ion membentuk ion hidronium)

Strengths of Acids in a Periodic Group
The greater the tendency for the transfer of a proton from HX to H2O, the stronger the acid.
(kecenderungan lebih besar untuk transfer proton dari HX ke H2O



Strengths of Acids in a Periodic Group
Bond-dissociation energy is inversely proportional to acid strength. The weaker the bond, the stronger the acid
( energi pemisahan
Anion radius is directly proportional to acid strength. The larger the resultant anion’s radius, the stronger is the acid

Strengths of Other Acids
For oxoacids, as the electronegativity of the central atom increases and as the number of terminal oxygen atoms increases, the acid strength also increases

( jika keeloktronegatifan dari pusat atom meningkat

Strengths of Other Acids
Carboxylic acids all have the -COOH group in common; therefore, differences in acid strength must come from differences in the R group attached to the carboxyl group

( asam karboksil mempunyai gugus –COOH, sehingga perbedaan kekuatan asam bergantung pada jumlah gugus R yang terikat pada gugus karboksil)

Strengths of Amines as Bases
Aromatic amines are much weaker bases than aliphatic amines
( amina aromatis lebih bersifat basa daripada amina aliphatik)
p electrons in the benzene ring of an aromatic molecule are delocalized and can involve the N’s lone-pair electrons in the resonance hybrid


Self-Ionization of Water
Water self-ionizes, that is, it creates a small amount of H3O+ and OH–
( ionisasi diri air membuat kecilnya jumlah H3O+ dan OH- )






( tetapan keseimbangan dalam proses ini disebut ion hasil dari air, ditulis dengan symbol Kw)

Self-Ionization of Water
Kw for water is calculated to be 1.0 × 10–14 M (at 25 oC)
This equilibrium constant is very important because it applies to all aqueous solutions—acids, bases, salts, and nonelectrolytes—not just to pure water
( Kw = tetapan ionisasi air = 10-14
Kw sangat penting digunakan untuk semua larutan encer {asam, basa, garam dan non elektrolit } tidak hanya untuk air murni)

pH and pOH
pH is a measure of the strength of an acid; low pH = stronger acid
pH = –log[H3O+] and [H3O+] = 10–pH

pOH is a measure of the strength of a base; low pOH = stronger base
pOH = –log[OH–] and [OH–] = 10–pOH

Ionization Constant Relationship
Kw is the negative logarithm of Kw and at 25 oC is equal to 14.00
pKw = pH + pOH = 14.00
Kw = [H+][OH–] = 1 × 10–14
For conjugate acid–base pairs …
Kw = (Ka)(Kb) = 1 × 10–14

Acid–Base Equilibrium Calculations

Some Ionization Constants


Polyprotic Acids
A monoprotic acid has one ionizable H atom per molecule e.g., HCl, hydrochloric acid








Salts from Acids and Bases
Salts of strong acids and strong bases form neutral solutions: e.g., NaCl
Salts of weak acids and strong bases form basic solutions: e.g., NaF
Salts of strong acids and weak bases form acidic solutions: e.g., NH4Cl
Salts of weak acids and weak bases form solutions that are acidic in some cases, neutral or basic in others
(- garam dari asam kuat dan basa kuat berbentuk larutan netral ex: NaCl
- garam dari asam lemah dan basa kuat berbentuk larutan dasar/utama ex: NaF
- garam dari asam kuat dan basa lemah berbentuk larutan asamm ex: NH4Cl
- garam dari asam lemah dan basa lemah berbentuk larutan asam dalam ???
The Common Ion Effect
If one solution contains a weak acid and another contains that acid and its conjugate base as a second solute, the two solutions have different pH values
The conjugate base is referred to as a common ion because it is found in both the weak acid and the anion
The common ion effect is the suppression of the ionization of a weak acid or a weak base by the presence of a common ion from a strong electrolyte
(Jika suatu larutan yang terdiri atas asam lemah dan yang lain terdiri atas asam dan basa konjugasinya, maka kedua larutan tersebut mempunyai nilai PH yang berbeda dst

Common Ion Effect Illustrated


Buffer Solutions
A buffer solution is a solution that changes pH only slightly when small amounts of a strong acid or a strong base are added
A buffer is prepared by mixing a weak acid with its salt (conjugate base) or by mixing a weak base with its salt (conjugate acid) in aqueous solutionThe acid component of the buffer can neutralize small added amounts of OH–, and the basic component can neutralize small added amounts of H3O+
Example: HF (hydrofluoric acid) and NaF (sodium fluoride)
( larutan buffer bla.bla.bal…
( larutan buffer merupakan :
- campuran asam lemah dengan garam {basa konjugasinya}
- campuran basa lemah dengan garam { asam konjugasinya) )

The acid component of the buffer can neutralize small added amounts of OH–, and the basic component can neutralize small added amounts of H3O+
(komponen asam dari larutan buffer dapat dinetralisis dengan penambahan sedikit OH- sedang komponen basa dapat dinetralisis dengan penambahan sedikit H3O+ )





Buffering Action

Catatan: penambahan dengan sedikit asam/ sedikit basa tidak akan merubah PH coz lar buffer

Buffer Solutions Equation
The Henderson–Hasselbalch equation is used to calculate pH in a buffer solution as follows:



Buffer Capacity and Buffer Range
There is a limit to the capacity of a buffer solution to neutralize added acid or base
In general, the more concentrated the buffer components in a solution, the more added acid or base the solution can neutralize
As a rule, a buffer is most effective if the concentrations of the buffer acid and its conjugate base are equal

Acid–Base Indicators
An acid–base indicator is a weak acid having one color and the conjugate base of the acid having a different color. One of the “colors” may be colorless.










Acid and base indicators
A common indicators used in introductory chemistry laboratories is litmus
In an acidic solution, [H3O+] is high. Because H3O+ is a common ion, it suppresses the ionization of the indicator acid

Common Indicators


Neutralization Reactions
At the equivalence point in a titration, the acid and base have been brought together in exact stoichiometric propotions
mol acid = mol base
The indicator endpoint and the equivalence point for a neutralization reaction can be best matched by plotting a titration curve, a graph of pH versus volume of titrant
(





Titration Curves





Titration Curve for Weak Acid–Strong Base














Lewis Acids and Bases
There are reactions in nonaqueous solvents, in the gaseous state, and even in the solid state that can be considered acid–base reactions in which Brønsted–Lowry theory is not adequate to explain.










( Terdapat reaksi di dalam pelarut-pelarut non encer, dalam keadaan gas dan padat dapat menjadi pertimbangan dalam reaksi asam basa di mana dalam teori Bronsted- Lowry hal ini tidak dapat dijelaskan)

Belum ada arti nya dlam bahasa Indonesia lhoo!!!!!!!!!!! Yang komplit