Acids, Bases and Salts (Chemistry 'O' level)
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Transcript of Acids, Bases and Salts (Chemistry 'O' level)
ACIDS, BASES & SALTSPREPARED BY: FAIZ ABDULLAH
ACIDS
Properties
Definition
Commonacids
Reactions
Weak Vs. Strong
DEFINITION
A compound which produces hydrogen ions, H+, when dissolved in water
Acid + H2O H+
STRONG VS WEAK ACIDS
Strong acids IONIZED COMPLETELY in water
Weak acids IONIZED PARTIALLY in water
HCl
water
H+
H+
H+Cl-
Cl-
Cl-
Strong AcidDissociate completely
WEAK ACIDS
water
CH3COOH
CH3COOH
CH3COOH
H+
H+
CH3COO-
CH3COO-
Weak acid doesNot dissociatecompletely
Ada CH3COOHMasih tetinggal
COMMON ACIDS
HCl
H2SO4
HNO3
CH3COOH
Sulfuric Acid
Nitric Acid
Ethanoic Acid
Hydrochloric Acid
PROPERTIESTaste: Sour taste
Litmus paper: Blue Red
REACTIONS OF DILUTE ACIDS
1. Some METALS to give SALT and HYDROGEN gas
Zn + 2HCL ZnCl2 + H2
2. Bases to give SALT and WATER only
2NaOH + H2SO4 Na2SO4 + H2O
3. Carbonates and hydrogencarbonates (insoluble or soluble) to give salt, water and CO2 gas
CaCO3 + 2HCl CaCl2 + H2O + CO2
IONS THAT ARE PRODUCED!
ACIDS BASES
H+ OH-
BASES
Properties
Definition
Commonbases
Reactions
Weak Vs. Strong
DEFINITION
Substance which reacts with an acid to form salt and water only
NEUTRALIZATION
ACIDS + BASE SALT + WATER
REACTIONS
1) Reacts with acids to produce salt and water only
2) Ammonium salts to produce AMMONIA
NaOH + NH4Cl NaCl + NH3 + H2O
AMMONIA
COMMON BASES
CaO
MgO
CuO
NaOH
NH3
Copper(II) Oxide
Calcium Oxide
Magnesium Oxide
Ammonia
Sodium Hydroxide
THEN, WHAT IS AN ALKALI
Alkali are BASES THAT ARE SOLUBLE IN WATER
BASES
Soluble in water Insoluble in water
ALKALI
ALKALI
PROPERTIES
Slippery
Turns Litmus paper:
Red Blue
Produces OH- when dissolved in water
DISSOCIATION EXAMPLES (REMEMBER)
Alkali when dissolved in water
NaOH OH- + Na+ NaOH
water
Na+
Na+
Na+OH-
OH-
OH-
WHAT IF WE TRY TO DISSOLVE AMMONIA GAS?
NH3 + H2O NH4+ + OH-
Do not forget OH-
AGAIN, WHAT IS A WEAK ALKALI?
Weak Alkali when dissolved in water
NH3 + H2O NH4+ + OH- NH3
water
OH-
OH-NH4
+
NH4+
NH3
NEUTRALIZATION
In neutralization, the H+ from the ACID and the OH- from the Alkali react to form water
H+ + OH- H2OEnergy
Energy is being released:EXOTHERMIC
OXIDES
ACIDIC OXIDES- OXIDES THAT ARE ACIDIC
BASIC OXIDES- OXIDES THAT ARE BASIC
AMPHOTERIC OXIDES- OXIDES THAT ARE ACIDIC AND BASIC
EXAMPLES OF OXIDES
BASIC ACIDIC
Na2O
CaO
Fe2O3
CO2
SO2
P4O10
Amphoteric
Al2O3
ZnO
H2O
CO, NONeutral
INDICATORS
Substances that change COLORS in acidic and alkaline solutions
Litmus indicator
Red
Blue
Acids
Bases
Phenolphthalein
Colorless
Red/Pink
Acids
Base
These are used inTITRATION
PH SCALE
pH is a number to show how acidic or alkaline a solution is
0 14
Superacidic
31 6 7 13108
Veryacidic
Becoming Less acidic
VeryLittleacidity
neutral
VeryLessalkaline
GettingLess basic
Super basic
Verybasic
EXAMPLES OF NEUTRAL SOLUTION
• Pure Water• NaCl solution• Most soluble salts• Ethanol solution(not ethanoic acid)
APPLICATION: PH IN SOIL
Soil
Most plants grow well almost neutral
Plants grow poorly in very highOr very low pH
Soil can become too acidic because:• Excessive use
of chemical fertilizers
• Acid rain from air pollution by sulfur dioxide and nitrogen oxides
How to fix an acidic soil?
SALTSA salt is obtained from an acid when the H+ is replaced by metal ion or ammonium ion
H ClAcid
Na
Salt
SOLUBILITY OF SALTS: MEMORIZE THIS PLEASE
Type of salts Soluble Insoluble
Carbonates (NH4)2CO3
Na2CO3
K2CO3
All the rest
Chlorides All the rest PbCl2AgCl
Nitrates All -
Sulfates All the rest BaSO4
PbSO4
(CaSO4 is slightly soluble)
PRACTICESoluble Insoluble
K2SO4
Na2CO3
KNO3
Pb(NO3)2
BaSO4
CuSO4
BaCO3
AgCl
HOW DO WE PREPARESALTS???
CASE 1: I WANT TO MAKE AN INSOLUBLE SALT, PBCL2 (SOLID)
Step 1: think where PbCl2 comes from:
Pb
Cl2
Pb2+
Cl-
An aqueous solution (soluble)Pb(NO3)3
An aqueous solution (soluble)NaCl
Step: 2 Precipitation reaction
Pb(NO3)2(aq) + NaCl(aq) NaNO3(aq) + PbCl2(s)Soluble SolubleSoluble Insoluble
ILLUSTRATION
water
Pb(NO3)2
solutionNaClsolution
Pb2+
NO3-
Na+
Cl-
Na+
Na+
NO3-
NO3-
NO3-
PbCl2 solid
GETTING THE SALT HOW?
We have solid in a liquid
Na+
Na+
NO3-
NO3-
NO3-
PbCl2 solid
FILTRATION
THIS IS HOW YOU GET PBCL2
CASE 2: SOLUBLE SALTS
• 1. acid + excess metal/insoluble metal oxide/carbonate• 2. acid+ alkali
HOW TO PREPARE SALTS
START
Is the salt soluble?
NO
YES React acid with metal/alkali/metal oxide/metal carbonate
Product soluble?
YESNO
Mix acid with excess metal/ metal oxide/metal carbonate
WORK THIS OUT:I WANT TO MAKE COPPER SULFATE
IONIC EQUATION FAIZ, DO IT ON THE BOARD