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