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