Chemistry C5 - Chemical changes Flashcards
Describe the reactions between metals and oxygen
A metal oxide is formed in an oxidation reaction
What do metal atoms do when they react?
They lose electrons to form positive ions
What do we call the order of how reactive metals are?
The reactivity series.
Which two non-metals are often included in the reactivity series?
Hydrogen and Carbon.
What is the reactivity series of the metals?
Potassium, sodium, lithium, calcium, magnesium, zinc, iron copper
Why are some metals more reactive than others?
They are more likely to form their positive ions
How are unreactive metals extracted?
They are found as the pure metal in the Earth.
How are metals less reactive than carbon extracted?
Their ore is heated with carbon and the metal is reduced.
What is oxidation?
The addition of oxygen.
What is reduction?
The removal of oxygen.
What happens to electrons during oxidation?
They are lost from the atom.
What happens to electrons during reduction?
The atom gains electrons.
- What are the products when acids and metals react?
2. What is oxidised in these reactions?
- Hydrogen gas and a salt.
2. The metal
What is an alkali?
A metal hydroxide, e.g. MOH
How do alkalis react with acids?
They neutralise the acid forming a salt and water
How can you name a salt?
The metal and negative ion from the acid
What do acids do when they dissolve?
Release H+ ions in water.
What do alkalis do when they dissolve?
Release OH- ions in water.
What is the pH scale?
A scale from 0-14 to measure the acidity or alkalinity of solutions.
How can you measure pH?
Universal indicator or a pH probe.
Which pH values are acidic?
0-6
Which pH values are neutral?
7
Which pH values are alkali?
8-14
What is neutralisation?
H(+) + OH(-) (rightward arrow) H(2)O
How can we determine the quantities of acid and alkali that will react?
Titration
Define a strong acid
An acid that completely ionises in water
Define a weak acid
An acid that partially ionises in water.
