Chemistry - Acids and Bases

Acids

-substances that release H⁺ ions when dissolved in water (the excess H⁺ ions make a solution acidic)

-they have a pH less than 7

Bases

-Substances that neutralise acids

-they have a pH greater than 7

-Metal oxides and hydroxides are bases

Alkalines

-soluble hydroxides

-a base dissolved in water

-they release OH⁻ in solutions (the excess OH⁻ ions make solutions alkaline)

pH scale

Measures how acidic or alkaline a solution is

meeausing acids

-pH is the measure of the concentration of H⁺ ions in a solution

-Every decrease of 1 on the pH scale is an increase in H⁺ by a factor of 10

-0.1 mol/dm³ = Ph1

-0.01 mol/dm³ = Ph2

salt

The product of a reaction in which the H⁺ ions from the acid are replaced by metal or ammonium ions.

neutralisation reaction

-Acid + base → salt + water

-Acid + alkali → salt + water

Acid + base

Acid + metal hydroxide → salt + water

Acid + metal oxide → salt + water

Acid + Metal Carbonate

Acid + Metal Carbonate → Salt + Water + Carbon dioxide

concentrated

A large amount of solute in a particular volume

dilute

A small amount of solute in a particular volume

ionic neutralisation reaction

H⁺(aq) + OH⁻(aq) →H20 (l)

Strong acids

-Fully dissociate in water

-This means that the acid molecules release H⁺ ions

-produce a high concentration of H⁺ ions so they have a low pH

-They are more reactive than weak acids at the same concentration

Weak acids

-partially ionise in water

-only some molecules release H⁺ ions

-They have a high pH

diluting acids

reduces the concentration of H⁺ ions so the ph icreases