Acids, Bases and Salts

What is an acid?

A substance that produces hydrogen ions (H+) in aqueas solution (when dissolved in water).

What is the pH of acids?

Lower than 7

What are some key acids?

Hydrochloric HCl

Sulfuric H₂SO₄

Nitric HNO₃

What is an alkali?

A soluble base that produces hydroxide ions (OH-) in aqueas solution

What is the pH of alkalis?

Greater than 7

What is a key alkali?

Sodium Hydroxide NaOH

What is the pH scale?

A scale that measures the level of acidity of alkalinity in a solution

What is an indicator?

Substances which turn different colours in acidic, alkaline or neutral solutions.

What colour does Universal Indicator turn in acids and alkalis?

Red to green in acids and blue to purple in alkalis

What are neutralisation reactions?

When acids and alkalis react together to form neutral solutions.

Acid + Alkali → ?

Salt + Water

What do neutralisation reactions form?

A salt and water

How can the salt be seperated in a neutralisation reaction?

Using Crystallisation

How are salts named?

They have a 2 part name, the first part is the metal from the alkali (usually a neutral oxide or a metal hydroxide), the second part is based on the acid.

Acid + metal carbonate → ?

Salt + water + carbon dioxide

Acid + metal → ?

Salt + hydrogen

What is a redox reaction?

The metal loses electrons (is oxidised), the H+ gains electrons (is reduced).

What is a base?

A substance that neutralises an acid (e.g an alkali)

What are the units of solubility?

g/100g of water

What is an independent variable?

Variables we choose to investigate

What is a dependent variable?

Variables you measure in a scientific investigation

What is a control variable?

Variables that need to be kept the same.