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
h
Can be dangerous
if handled improperly
IRRITANT
i
Chemical can cause skin
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
sour
taste
Can be
harmful or
corrosive
React
with
metals
Produce
H+ ions
in water
Weak acid:
lemon
juice
Strong acid:
battery
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
bitter
taste
Can be
harmful or
corrosive
Feel
soapy or
slippery
Produce OH
+ ions
in water
Weak base:
hand
soap
Strong base:
drain
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 turn
onlylitmus
turns two
colors:
Acids
paper
RED.
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
2
1
0
Acids
Oven Cleaner
14
13
Bleach
12
11
Detergent
Baking Soda
10
9
8
7
6
5
Blood
Rainwater
4
3
2
Lemon Juice
1
0
Battery Acid
Recall
Acids are chemicals
that produce
H+ ions when
dissolved in water.
For example, take
hydrochloric acid (HCl)…
HCl à H+ + Cl-
HCl
Recall
Acids are chemicals
that produce
H+ ions when
dissolved in water.
Strong acids release
their H+ ions quickly
pH
0-3
Weak acids release
their H+ ions slowly
pH
4-6
Recall
Bases are chemicals
that produce
OH- ions when
dissolved in water.
For example, take sodium
hydroxide (NaOH)…
NaOH à Na+ + OH-
NaOH
Recall
Bases are chemicals
that produce
OH- ions when
dissolved in water.
Strong bases release
their OH+ ions quickly
pH
11-14
Weak acids release
pH
+ + ONaOH
à
Na
+
their OH ions slowly
8-10
Any Questions?
Acids and Bases
Part 2: Neutralization
Neutralization
Acids and bases are
chemical opposites.
acid
This means that
they can cancel
each other out.
base
A neutralization reaction occurs
when an acid combines with a base.
Neutralization
water + salt
acid
base
A neutralization,
neutralization an
reaction
occurswith
During
acid reacts
when
acid combines
withand
a base.
a base
toan
produce
pure water
a salt.
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?