Acids and Bases
Year 10
What are Acids?
Acids are
common
Some are
dangerous and
can burn your
skin
Some are safe to
eat and drink
Stomach acid
helps digest food explosion
Acids
Definition
• A group of compounds which behave similarly
• All have low pH
• Turn Litmus paper RED
• All donate H+ ions in aqueous solution
Examples
• Hydrochloric HCl
• Sulfuric H2SO4
• Nitric HNO3
• Ethanoic CH3COOH
Acids
A dilute acid has lots of water and a
small amount of acid
A concentrated acid has lots of acid
and not much water so must be
handled carefully
A strong acid releases lots of H+
A weak acid releases fewer H+
What are Bases (Alkalis)?
In our home we
often use bases
to clean things.
Eg Bleach and
toothpaste
Some things are
not acids or
bases, we say
that they are
neutral. Eg
Water
Bases
Definition
• A family of compounds that behave
similarly
• Have a high pH
• Turn litmus BLUE
• All donate OH-
Examples
• Ammonia NH3
• Sodium Hydroxide NaOH
Measuring acid strength?
To decide if something is an acid or a
base we can use an indicator.
Litmus and Universal Indicator are
examples of indicators.
They change colour depending on if
they are in an acid or a base.
Working with Indicators
Red litmus turns BLUE in the
presence of Bases
Blue litmus turns RED in the
presence of acid
Acids and bases react together in
a NEUTRALISATION reaction
Acid Reactions
Acid + Base Salt + Water
Acid + Metal Salt + Hydrogen
Acid + Carbonate Salt + Water + Carbon Dioxide
• Hydrochloric acids (HCl) form CHLORIDE salts
• Nitric acid (HNO3) forms NITRATE salts
• Sulfuric acid (H2SO4) forms SULFATE salts
Acid Rain
Consider
• Causes
natural
human
• Effects
buildings
flora
fauna
health
• Chemical equations
• Prevention/Solution
Testing Gases
Hydrogen -
Testing Gases
Hydrogen - POP TEST
• Explodes with a squeaky pop
Carbon Dioxide –
Testing Gases
Hydrogen - POP TEST
• Explodes with a squeaky pop
Carbon Dioxide – Limewater goes
cloudy
Oxygen –
Testing Gases
Hydrogen - POP TEST
• Explodes with a squeaky pop
Carbon Dioxide – Limewater goes
cloudy
Oxygen – Relights a glowing splint
Antacid Investigation
NZ facts 2007
• 70% population get
heartburn /GERD
• $9m on 1 brand!
• 3rd most widely
prescribed medicine
Which brand is the
best?
Identify Unknown Solutions
Rates of Reaction
Factors increasing the rate of
reaction
•Surface area
•Concentration
•Temperature
•Catalyst/Enzyme
•Pressure
Metals/periodic table
, Element, compound, exo/endo