ACIDS AND BASES
, Definitions
* Arrhenius (Acid ) ions ( Ht ) when it dissolves
Theory → a substance that produces hydrogen
in water .
* Arrhenius Theory ( Base )
-
→ a substance that
produces hydroxide ions I0H ) when it dissolves
in water .
* Lowry Bronsted Theory
-
( Acid ) → a proton ( Ht ion ) do her .
* Lowry Bronsted Theory
-
( Base ) → a proton ( Ht ion ) accept or
+
* acid → Ionise completely in water to form a high concentration of H30 ions
strong .
+
* Weak Acid → Ionise in completely in water to form a low concentration of H30 ions .
-
*
strong Base → dissociate completely in water to form a
high concentration of OH ions .
* Weak Base → dissociate / ionise in
-
water to form concentration of OH ions
completely in a low .
* concentrated Acid / Base → contain a large amount ( number of moles ) of acid / Base in
to the volume of water
proportion .
* Dilute Acid / Base → contain a small amount ( number of moles ) of acid / Base in proportion
to the volume of water .
*
Ampholyte → a substance that can act as either an acid or a base .
the reaction of water with itself to form H } Ot and OH
-
* Auto -
ionisation of water → ions .
* KW -
the equilibrium constant for ionisation of water or the ionic product of water
or the ionisation constant of water .
*
Equivalence point → the point at which the acid / Base has completely reacted with the base/acid .
,Acids
* General Information :
↳ When placed in water acids will donate their
, protons to water
during an ionisation reaction .
↳
Lowry
-
Bron sted Acid :
↳ Acid =
a proton done r
↳ Arrhenius :
↳ Acid =
a substance that ionizes in a solution to produce H?
+
Acids are linked to H30 (
↳
hydro nium) and Ht (proton ) ions
* Acids :
strong
acids ionise
↳
strong :
completely
↳ Form WEAK CONJUGATE BASES
↳ Use a single arrow ( → ) to show the reaction .
Common strong Acids
HC1 Acid
Hydrochloric
HN03 Nitric Acid
1-12504 Sulphuric Acid
* weak Acids :
↳ Weak acids ionise
partially
:
↳ Form STRONG CONJUGATE ACIDS
↳ Use a double arrow (E) to show the reaction .
Common weak Acids
CH3 CO0H Ethan oic Acid
H2 C03 Carbonic Acid
(CO0H)z Oxalic Acid
HF Acid
Hydrofluoric
1-12503 Sulphurous Acid
H3 P04 Phosphoric Acid
,* Acid
proticity
:
↳ the number of
protons that an acid can donate
↳ acids that donate more than one proton =
polyprotic acids
of proti city
↳
Types
:
•
mono pro tic ( donates one proton ) Trip rotic ( donates three protons )
• : :
-
HC1E Ht H > PO4E Htt H2 P04
-
+ Cl
-2
Hz PO4E Ht + HP04
-3
•
diprotic ( donates two protons )
: HP04 f- Ht + PO4
1-12504 f- Ht
-
+ HS04
1-1504=-1-1++504-2
Bases
* General Information :
↳ dissociate when placed in water
↳ Lowry -
Brons ted :
Base
↳ =
a
proton acceptor
↳ Arrhenius :
01-1 ions
-
↳ Base = a substance that dissociates to produce .
↳ Some bases are INSOLUBLE
↳ a base dissolved in water → ALKALI
* Bases :
strong
base dissociate
↳ strong :
completely in aqueous solution
↳ FORM WEAK CONJUGATE ACIDS
common strong Bases
NA0H Sodium Hydroxide
K0H Potassium Hydroxide
[a (01-1) a calcium Hydroxide
Mg 101-112 Magnesium Hydroxide
,* weak Bases :
↳ weak bases : dissociate partially in aqueous solution .
↳ FORM STRONG CONJUGATE ACIDS
common weak Bases
NH3 Ammonia
Naz C03 Sodium carbonate
Coco } Calcium carbonate
Na HC03 Sodium Bicarbonate
conductivity
*
Properties of
strong acids and Bases :
↳
strong acids ionise
completely and
strong bases dissociate completely :
① increases number of ions in a solution .
② There are more free
flowing ions in a solution, which means the solution will have
a
higher conductivity .
③ The more free
flowing ions also has the
potential to increase the rate of the reaction
Ionisation vs Dissociation
Ionisation Dissociation
* Acids * Bases
* Reacts WITH water * Reacts IN water
* MOLECULAR compounds , and * IONIC
compounds
therefore it does not contain
ions .
* when it reacts with water, * when dissolved in water the
,
the acid donates a proton base dissociates into its
creating ionic substances .
ionic compound .
,pH scale
*
pH measures the concentration of Ht ions in a solution
*
pH of a solution → represents the
acidity or alkalinity of a solution .
↳ Greater concentration of Ht ions more acidic and lower pH
=
.
↳ Lower concentration of Ht ions = more alkali and higher pH .
strong weak weak strong
0 I 2 3 4 5 6 7 8 9 10 11 12 13 14
I 1
I 1
acidic
neutral Basic
concentrated us Dilute
* Not the same as
strength
* Amount of solute ( acid )
per unit solvent ( water )
↳ small amount =
weak acid
↳
large amount =
strong acid
-3
Eg . 1.0 moi dm . HC1 → concentrated :
high ratio of dissolved solute in solvent
0.0001 MO1 dm -3 HC1 . → dilute : low ratio of dissolved solute in solvent
concentrated dilute
→
solvent
solvent
acid acid
more acid
particles
per unit
volume
Ampholyte or Amphoteric substances
*
Ampholyte : a substance which can act as both an acid and base .
↳ can accept OR donate their protons .
-3
↳ most H20 HC0 and HS0;
common ampholytes
:
;
* Most Ht ion
polyprotic acids after
donating a can be an ampholyte
↳ they can donate/accept protons .
Eg HS04
-
. as an
ampholyte :
acid : 1-1504-+1-120=-504-2 + H30+
1-1501+1-120=-1-12504 OH
-
base : +
,Conjugate Acid Base Pairs
-
* Acid will donate a Ht and the base will accept the Ht ( proton transfer )
*
conjugate acid base
-
pairs differ by 1- Ht ( can be more than 1 Ht )
↳ difference by a hydrogen and a
charge .
Base → Base + Ht
( Becomes more
basic )
* Acid + Base → conjugate Base +
conjugate Acid
acid → Acid -
Ht
( becomes more
basic )
*
conjugate pairs :
strong acid E- weak base
strong base ⇐ weak acid
Indicators
* Methyl orange :
acid weak Base
↳
strong +
Acidic Neutral Basic PH
Red
orange yellow 3-4
* Blue :
Bromothyl
↳ acid base
strong +
strong
↳ Weak Acid + weak Base
Acidic Neutral Basic pH
yellow Green Blue 6- 8
*
phenolphthalein :
↳ weak Acid + weak Base
Acidic Neutral Basic PH
Clear light pink 8-10
pink
, and scale
pH pot
*
pH scale :
↳ pH is calculated
using concentration of Ht or H }0t
pH= log 11-130+1
-
* P0H scale :
↳ pot is calculated using
P0H = -
Log 101-1-1
*
Using the two formulas above the
, following equation is derived :
14
pH +
P0H =
*
summary :
Acidic 11-1+1>101-1-1
PH9 P0H >7
Basic [ 1-1+3=[01-1] p0H=7
pH=7
Neutral 11-1+3<101-1-3 pH >7 P0H ( 7
Example (same as on the
previous page ) :
[ OH -1=0.7 MO1 dm .
-3
"
[ 1-130+1=1.43×10-1 moi .
dm -3
P0H = -
Log I0H] P0H +
pH =x
Log ( 0.7 ) 0.15490196 + 13.84466396
-
=
=x
=
0.15490196 13.99956 =x
"
pH =
log CH30 ] 141k
-
Log (1.43×10-14)
•
you know
your previous calculations
= -
• .
= 13.84466396 are correct .
,Salt
Hydrolysis
* Reaction between an acid and base
produces a salt .
↳ also known as a neutralisation reaction .
↳ neutral solutions not be formed
may or
may .
*
Hydrolysis : reaction of anion from a salt with water .
Acidic Salt Neutral Salt Basic salt
Acid Base Acid strong Base weak Acid
strong +
strong strong + + weak Base
weak Acid + Weak Base
General solution : No General solution :
hydrolysis takes
•
weak base forms a
strong place .
•
weak acid forms a
strong
conjugate acid .
conjugate base .
acid reacts with conjugate base reacts with
conjugate
• •
the water and donates the water and removes
Ht ion . a Ht ion .
concentration of H } Ot concentration of OH
-
• •
increases . increases .
pH decreases pH increases
•
•
•
solution becomes more •
solution becomes more
acidic basic .
Ka constant
* Ka is constant ( no unit ) value , acid
a
measuring the
strength of an .
* HA t 1-120 A- + H30 +
[ A- I. 11-130+3
Ka ) I =
strong acid
Ka= I1-1AI Kal 1 =
weak acid
↳ Don't include solids and
liquids in Ka expression .
, Example :
calculate the Ka value .
-3
0.1 M01 Of HF is dissolved in 1dm water Determine the Ka of HF if the
.
equilibrium concentration of Ht is 7.94×10-3 HF dissociates according
.
to
the
following chemical equation
:
HFcaq.IE/-HcaqstF-caq ) .
1
HF Ht F-
Ratio 1 I 1
Initial moi .
0.1 0 0
Change M01 .
-7.9×10-3 +7.9×10-3 +7.9×10-3
equilibrium mot 0.092 7.94×10+3 7.94×10+3
equilibrium cone .
0.092 i. I 794×10-3 :-| 7.94×10-3 :-|
(= 0.092 7.94×10-3 7.94×10-3
"
✗ a-
17.9×10 3) [7.94×10-3]
-
=
[0.0927
= 6.85×10-4
K6 Constant
* Kb is constant ( no unit ) value ,
a
measuring the
strength of a base .
'
13+1-120=01-1 HB
-
* +
IOH-1.lt/BtJK6=
(B) K6 > 1- =
strong base
K6C I =
weak base
↳ Don't include solids and
liquids in Ka expression .
, Definitions
* Arrhenius (Acid ) ions ( Ht ) when it dissolves
Theory → a substance that produces hydrogen
in water .
* Arrhenius Theory ( Base )
-
→ a substance that
produces hydroxide ions I0H ) when it dissolves
in water .
* Lowry Bronsted Theory
-
( Acid ) → a proton ( Ht ion ) do her .
* Lowry Bronsted Theory
-
( Base ) → a proton ( Ht ion ) accept or
+
* acid → Ionise completely in water to form a high concentration of H30 ions
strong .
+
* Weak Acid → Ionise in completely in water to form a low concentration of H30 ions .
-
*
strong Base → dissociate completely in water to form a
high concentration of OH ions .
* Weak Base → dissociate / ionise in
-
water to form concentration of OH ions
completely in a low .
* concentrated Acid / Base → contain a large amount ( number of moles ) of acid / Base in
to the volume of water
proportion .
* Dilute Acid / Base → contain a small amount ( number of moles ) of acid / Base in proportion
to the volume of water .
*
Ampholyte → a substance that can act as either an acid or a base .
the reaction of water with itself to form H } Ot and OH
-
* Auto -
ionisation of water → ions .
* KW -
the equilibrium constant for ionisation of water or the ionic product of water
or the ionisation constant of water .
*
Equivalence point → the point at which the acid / Base has completely reacted with the base/acid .
,Acids
* General Information :
↳ When placed in water acids will donate their
, protons to water
during an ionisation reaction .
↳
Lowry
-
Bron sted Acid :
↳ Acid =
a proton done r
↳ Arrhenius :
↳ Acid =
a substance that ionizes in a solution to produce H?
+
Acids are linked to H30 (
↳
hydro nium) and Ht (proton ) ions
* Acids :
strong
acids ionise
↳
strong :
completely
↳ Form WEAK CONJUGATE BASES
↳ Use a single arrow ( → ) to show the reaction .
Common strong Acids
HC1 Acid
Hydrochloric
HN03 Nitric Acid
1-12504 Sulphuric Acid
* weak Acids :
↳ Weak acids ionise
partially
:
↳ Form STRONG CONJUGATE ACIDS
↳ Use a double arrow (E) to show the reaction .
Common weak Acids
CH3 CO0H Ethan oic Acid
H2 C03 Carbonic Acid
(CO0H)z Oxalic Acid
HF Acid
Hydrofluoric
1-12503 Sulphurous Acid
H3 P04 Phosphoric Acid
,* Acid
proticity
:
↳ the number of
protons that an acid can donate
↳ acids that donate more than one proton =
polyprotic acids
of proti city
↳
Types
:
•
mono pro tic ( donates one proton ) Trip rotic ( donates three protons )
• : :
-
HC1E Ht H > PO4E Htt H2 P04
-
+ Cl
-2
Hz PO4E Ht + HP04
-3
•
diprotic ( donates two protons )
: HP04 f- Ht + PO4
1-12504 f- Ht
-
+ HS04
1-1504=-1-1++504-2
Bases
* General Information :
↳ dissociate when placed in water
↳ Lowry -
Brons ted :
Base
↳ =
a
proton acceptor
↳ Arrhenius :
01-1 ions
-
↳ Base = a substance that dissociates to produce .
↳ Some bases are INSOLUBLE
↳ a base dissolved in water → ALKALI
* Bases :
strong
base dissociate
↳ strong :
completely in aqueous solution
↳ FORM WEAK CONJUGATE ACIDS
common strong Bases
NA0H Sodium Hydroxide
K0H Potassium Hydroxide
[a (01-1) a calcium Hydroxide
Mg 101-112 Magnesium Hydroxide
,* weak Bases :
↳ weak bases : dissociate partially in aqueous solution .
↳ FORM STRONG CONJUGATE ACIDS
common weak Bases
NH3 Ammonia
Naz C03 Sodium carbonate
Coco } Calcium carbonate
Na HC03 Sodium Bicarbonate
conductivity
*
Properties of
strong acids and Bases :
↳
strong acids ionise
completely and
strong bases dissociate completely :
① increases number of ions in a solution .
② There are more free
flowing ions in a solution, which means the solution will have
a
higher conductivity .
③ The more free
flowing ions also has the
potential to increase the rate of the reaction
Ionisation vs Dissociation
Ionisation Dissociation
* Acids * Bases
* Reacts WITH water * Reacts IN water
* MOLECULAR compounds , and * IONIC
compounds
therefore it does not contain
ions .
* when it reacts with water, * when dissolved in water the
,
the acid donates a proton base dissociates into its
creating ionic substances .
ionic compound .
,pH scale
*
pH measures the concentration of Ht ions in a solution
*
pH of a solution → represents the
acidity or alkalinity of a solution .
↳ Greater concentration of Ht ions more acidic and lower pH
=
.
↳ Lower concentration of Ht ions = more alkali and higher pH .
strong weak weak strong
0 I 2 3 4 5 6 7 8 9 10 11 12 13 14
I 1
I 1
acidic
neutral Basic
concentrated us Dilute
* Not the same as
strength
* Amount of solute ( acid )
per unit solvent ( water )
↳ small amount =
weak acid
↳
large amount =
strong acid
-3
Eg . 1.0 moi dm . HC1 → concentrated :
high ratio of dissolved solute in solvent
0.0001 MO1 dm -3 HC1 . → dilute : low ratio of dissolved solute in solvent
concentrated dilute
→
solvent
solvent
acid acid
more acid
particles
per unit
volume
Ampholyte or Amphoteric substances
*
Ampholyte : a substance which can act as both an acid and base .
↳ can accept OR donate their protons .
-3
↳ most H20 HC0 and HS0;
common ampholytes
:
;
* Most Ht ion
polyprotic acids after
donating a can be an ampholyte
↳ they can donate/accept protons .
Eg HS04
-
. as an
ampholyte :
acid : 1-1504-+1-120=-504-2 + H30+
1-1501+1-120=-1-12504 OH
-
base : +
,Conjugate Acid Base Pairs
-
* Acid will donate a Ht and the base will accept the Ht ( proton transfer )
*
conjugate acid base
-
pairs differ by 1- Ht ( can be more than 1 Ht )
↳ difference by a hydrogen and a
charge .
Base → Base + Ht
( Becomes more
basic )
* Acid + Base → conjugate Base +
conjugate Acid
acid → Acid -
Ht
( becomes more
basic )
*
conjugate pairs :
strong acid E- weak base
strong base ⇐ weak acid
Indicators
* Methyl orange :
acid weak Base
↳
strong +
Acidic Neutral Basic PH
Red
orange yellow 3-4
* Blue :
Bromothyl
↳ acid base
strong +
strong
↳ Weak Acid + weak Base
Acidic Neutral Basic pH
yellow Green Blue 6- 8
*
phenolphthalein :
↳ weak Acid + weak Base
Acidic Neutral Basic PH
Clear light pink 8-10
pink
, and scale
pH pot
*
pH scale :
↳ pH is calculated
using concentration of Ht or H }0t
pH= log 11-130+1
-
* P0H scale :
↳ pot is calculated using
P0H = -
Log 101-1-1
*
Using the two formulas above the
, following equation is derived :
14
pH +
P0H =
*
summary :
Acidic 11-1+1>101-1-1
PH9 P0H >7
Basic [ 1-1+3=[01-1] p0H=7
pH=7
Neutral 11-1+3<101-1-3 pH >7 P0H ( 7
Example (same as on the
previous page ) :
[ OH -1=0.7 MO1 dm .
-3
"
[ 1-130+1=1.43×10-1 moi .
dm -3
P0H = -
Log I0H] P0H +
pH =x
Log ( 0.7 ) 0.15490196 + 13.84466396
-
=
=x
=
0.15490196 13.99956 =x
"
pH =
log CH30 ] 141k
-
Log (1.43×10-14)
•
you know
your previous calculations
= -
• .
= 13.84466396 are correct .
,Salt
Hydrolysis
* Reaction between an acid and base
produces a salt .
↳ also known as a neutralisation reaction .
↳ neutral solutions not be formed
may or
may .
*
Hydrolysis : reaction of anion from a salt with water .
Acidic Salt Neutral Salt Basic salt
Acid Base Acid strong Base weak Acid
strong +
strong strong + + weak Base
weak Acid + Weak Base
General solution : No General solution :
hydrolysis takes
•
weak base forms a
strong place .
•
weak acid forms a
strong
conjugate acid .
conjugate base .
acid reacts with conjugate base reacts with
conjugate
• •
the water and donates the water and removes
Ht ion . a Ht ion .
concentration of H } Ot concentration of OH
-
• •
increases . increases .
pH decreases pH increases
•
•
•
solution becomes more •
solution becomes more
acidic basic .
Ka constant
* Ka is constant ( no unit ) value , acid
a
measuring the
strength of an .
* HA t 1-120 A- + H30 +
[ A- I. 11-130+3
Ka ) I =
strong acid
Ka= I1-1AI Kal 1 =
weak acid
↳ Don't include solids and
liquids in Ka expression .
, Example :
calculate the Ka value .
-3
0.1 M01 Of HF is dissolved in 1dm water Determine the Ka of HF if the
.
equilibrium concentration of Ht is 7.94×10-3 HF dissociates according
.
to
the
following chemical equation
:
HFcaq.IE/-HcaqstF-caq ) .
1
HF Ht F-
Ratio 1 I 1
Initial moi .
0.1 0 0
Change M01 .
-7.9×10-3 +7.9×10-3 +7.9×10-3
equilibrium mot 0.092 7.94×10+3 7.94×10+3
equilibrium cone .
0.092 i. I 794×10-3 :-| 7.94×10-3 :-|
(= 0.092 7.94×10-3 7.94×10-3
"
✗ a-
17.9×10 3) [7.94×10-3]
-
=
[0.0927
= 6.85×10-4
K6 Constant
* Kb is constant ( no unit ) value ,
a
measuring the
strength of a base .
'
13+1-120=01-1 HB
-
* +
IOH-1.lt/BtJK6=
(B) K6 > 1- =
strong base
K6C I =
weak base
↳ Don't include solids and
liquids in Ka expression .
