S2 - Acids and Bases (complete) Flashcards
Acidic
Sour and corrosive. Contains hydrogen. pH < 7.
Alkaline
Slippery and soapy. Corrosive. pH >7.
Neutral
Neither acidic nor alkaline.
pH
A number that describes how acidic something is.
Low pH = acidic.
pH scale
A colour scale showing the colours of a pH indicator in different pH.
pH indicator
A chemical compound (dye) that changes colour in different pH.
Universal indicator
A pH indicator which turns red/orange/yellow in acids, green in neutral solutions and blue/purple in alkalis.
Acids or alkalis?
Lemon juice, vinegar, yoghurt
Acids
Acids or alkalis?
Bleach, drain cleaner, baking soda
Alkalis
Preservative
A substance that stops food from spoiling.
Besides flavour, why are acids added to food?
To act as preservatives.
What negative effect do acids in food have on your health?
Can cause tooth decay or indigestion.
Concentration
The number of stuff/particles dissolved in a liquid.
Dilution
Adding water to a solution.
When you dilute an acid, the pH ________.
increases
(can go up to 7)
When you dilute an alkali, the pH ________.
decreases
(can go down to 7)
When you dilute a neutral solution, the pH _______.
does not change
(already 7)
Base
A substance that neutralises an acid.
Soluble
Dissolves in water.
Alkali
A soluble base.
Neutralisation
A reaction between an acid and a base which produces a salt and water.
During neutralisation, the pH of the alkali _______.
drops toward 7
During neutralisation, the pH of the acid _______.
rises toward 7
Salt
A compound made during neutralisation. It is made when the hydrogen in an acid is replaced with a metal.
What types of substances are bases?
Metal oxides
Metal hydroxides
Metal carbonates
Parent acid
An acid used to make a salt.
Parent base
A base used to make a salt.
Antacid
Medicine to treat indigestion which helps neutralise stomach acid.
Evaporation
Removing solvent (liquid) by heating a solution.
Acid rain
Rain with pH lower than normal.
Ocean acidification
The process of ocean water becoming more acidic over time.
HCl is a formula for an acid.
How can we tell this is an acid?
Contains hydrogen.
When is it useful to do a microscale investigation?
When the reactants are expensive, toxic or only available in small quantities.
Which acid is stomach acid?
Hydrochloric acid
How do antacids work?
They contain a base which neutralises stomach acid.
Hydrochloric acid makes ______ salts.
chloride
Sulfuric acid makes ______ salts.
sulfate
Nitric acid makes _______ salts.
nitrate
Phosphoric acid makes ______ salts.
phosphate
Potassium chloride is a salt name.
Where does the ‘potassium’ part come from?
Parent base
(potassium oxide, hydroxide or carbonate)
Potassium chloride is a salt name.
Where does the ‘chloride’ part come from?
Parent acid
(hydrochloric acid)
You have a salt dissolved in water.
What technique will let you separate the salt and the water?
Evaporation
Fill in the blank:
How do you show on this diagram that you are heating the mixture?
Which gases cause acid rain?
Sulfur dioxide, nitrogen oxides, carbon dioxide
Which gas is always produced when fossil fuels are burned?
Carbon dioxide (CO2)
Sulfur dioxide gas can be made when coal is burned.
Why is this bad?
Sulfur dioxide is harmful to the respiratory system, and causes acid rain.
Where is nitrogen dioxide formed?
In car engines and furnaces.
Acid rain is harmful to __________________________.
plants and aquatic life
What does acid rain do to rock and metal surfaces?
It wears away rock surfaces and corrodes metal surfaces.
Why are the oceans becoming more acidic?
Because of carbon dioxide dissolving in ocean water.
