Acids and Bases
Part 1: What are Acids and Bases?
Warning!
Acids and bases can be dangerous.
Acids and bases can be
harmful, irritating or corrosive.
Chemists use labels
called hazard signs
to show the risks of
handling different
acids and bases.
HARMFUL
Can be dangerous
h if handled improperly
IRRITANT
Chemical can cause skin
i
reddening or blistering
CORROSIVE
Chemical can attack and
damage skin and eyes
What Are Acids?
Acids are chemicals
that produce
H+ ions when
dissolved in water.
Some properties of
acids include…
Properties of Acids
Have a Can be React
sour harmful or with
taste corrosive metals
Produce Weak acid: Strong acid:
H+ ions lemon battery
in water juice acid
What Are Bases?
Bases are chemicals
that produce
OH- ions when
dissolved in water.
Some properties of
bases include…
Properties of Bases
Have a Can be Feel
bitter harmful or soapy or
taste corrosive slippery
Produce OH Weak base: Strong base:
+ ions hand drain
in water soap cleaner
Indicators
Indicators are special dyes that
change color in acids or bases.
Indicators allow us to test for acids
and bases without touching them.
We will use 2
different indicators...
Litmus Paper
Universal Indicator
Litmus
Litmus is a natural indicator made
from tiny plants called lichens.
Litmus only turns paper RED.
Acids turn litmus two colors:
Bases turn litmus paper BLUE.
Universal Indicator
Universal Indicator (UI) is a mixture of dyes.
U.I. produces a range of colors depending
on the strength of the acid or base.
Strong acids turn U.I. RED
Weak acids turn U.I. YELLOW
Weak bases turn U.I. BLUE
Strong bases turn U.I. PURPLE
Bases
Neutral
Acids
The pH Scale
Acids can be strong or weak.
The pH scale rates the strength
of acids or bases from 0 - 14
pH stands for potential of
hydrogen and describes
how easy a substance
releases H+ ions when
dissolved in water
14
13
12
11 Bases
10
9
8
Neutral 7
6
5
4
3 Acids
2
1
0
Oven Cleaner 14
13
Bleach 12
11
Detergent 10
9
Baking Soda 8
7
Blood
6
5
Rainwater
4
3
2 Lemon Juice
1
0 Battery Acid
Recall
Acids are chemicals
HCl
that produce
H+ ions when
dissolved in water.
For example, take
hydrochloric acid (HCl)…
HCl à H+ + Cl-
Recall
Acids are chemicals
that produce
H+ ions when
dissolved in water.
Strong acids release pH
their H+ ions quickly 0-3
Weak acids release pH
their H+ ions slowly 4-6
Recall
Bases are chemicals
NaOH
that produce
OH- ions when
dissolved in water.
For example, take sodium
hydroxide (NaOH)…
NaOH à Na+ + OH-
Recall
Bases are chemicals
that produce
OH- ions when
dissolved in water.
Strong bases release pH
their OH+ ions quickly 11-14
Weak acids release - pH
NaOHionsNa+ + O 8-10
their OH+ à slowly
Any Questions?
Acids and Bases
Part 2: Neutralization
Neutralization
Acids and bases are
chemical opposites.
This means that
they can cancel
acid each other out. base
A neutralization reaction occurs
when an acid combines with a base.
Neutralization
water + salt
acid base
A neutralization reaction occurs
During neutralization, an acid reacts with
when produce pure water and a salt.
a base toan acid combines with a base.
Uses of Neutralization
Neutralisation can be a very useful reaction.
It can be used to cure indigestion.
Indigestion is caused by the
stomach making too much acid.
It can be cured by taking
antacid tablets, like TUMS.
The tablets are a weak base
that neutralizes the extra acid.
Uses of Neutralization
Neutralisation can be a very useful reaction.
It can be used to cure bee stings.
Bee sting hurt because
they are highly acidic.
They can be cured by
applying a weak base,
such as toothpaste!
Uses of Neutralization
Neutralisation can be a very useful reaction.
It can be used to cure wasp stings.
Wast sting hurt because
they are highly basic.
They can be cured by
applying a weak acid,
such as vinegar!
Uses of Neutralization
Neutralisation can be a very useful reaction.
It can be used to cure cavities.
You get cavities because
acids in foods make holes
in your tooth enamel.
Brushing with a mildly
basic toothpaste
neutralizes these acids!
Any Questions?