Chemistry Acids and Bases

Low numbers on pH scale

Acidic

High numbers on pH scale

Alkaline

You measure pH by…

An indicator or a pH probe

Why is a pH probe better to measure pH?

It’s more accurate

Acid

Any substance that forms an aqueous solution with a pH lower than 7

Base

Any substance with a pH higher than 7

Acids release… in water making it acidic

H+ ions

Alkalis

A sub group of bases soluble in water

Alkalis form… in water

OH- ions

Neutralisation reaction

An acid and a base reacted together

Product of neutralisation reaction

A salt and water

Acids and bases are neutralised to form a substance with a pH of…

7

acid + alkali product

salt + water

acid + metal product

salt + hydrogen

acid + metal oxide product

salt + water

Hydrochloric

Acid, HCl

Sulfuric

Acid, H2SO4

Nitric

Acid, HNO3

Sodium hydroxide

Base, NaOH

Calcium carbonate

Base, CaCO3

Acids… in aqueous solutions

Ionise

Ionise

Releases hydrogen ions

Strong acids all…

Ionise completely (reactants turn fully into products)

Examples of weak acids

Ethanoic, citric, carbonic

The ionisation of a weak acid is…

Reversible

In a weak acid, there is an…

Equilibrium between the undissociated and dissociated

Strength

How much an acid dissociates

Concentration

How much acid there is in a certain volume

More concentrated solutions…

Contain more acid

As the concentration of H+ ions gets higher…

The pH gets lower

As you move from a pH of 7 to a pH of 6, the concentration of hydrogen ions…

Multiplies by 10

To get an acid with a low pH…

You need a high concentration of H+ ions

When metal oxides or metal hydroxides react with an acid, they form…

A salt and water

When acids react with a metal carbonate, you get…

A salt, water and carbon dioxide

To make a soluble salt, you…

React an acid with an insoluble base

Examples of soluble salts

calcium carbonate, lead sulfate, iron hydroxide

Salt

A compound that contains a positive ion and a negative ion

Salts of sodium, potassium, and ammonium are

Soluble SPA

Nitrate salts are…

Soluble N

Common chlorides are…

Soluble apart from silver and lead chlorides

Common sulfates are…

Soluble

Common carbonates and hydroxides are…

Insoluble except sodium, potassium and ammonium

which salt would be produced if you reacted a metal with hydrochloric acid

(metal) chloride

which salt would be produced if you reacted a metal with nitric

(metal) nitrate

which salt would be produced if you reacted a metal with sulfuric acid

(metal) sulfate

which salt would be produced if you reacted a metal with ethanoic acid

(metal) ethanoate