Seneca C4 Flashcards
Acids
Acids are substances that form hydrogen (H+) ions when they dissolve in water (aqueous solutions).
The pH scale
The pH scale is used to measure how acidic or alkaline a substance is.
Alkalis
Alkalis are substances that form hydroxide (OH-) ions when they dissolve in water (aqueous solutions).
An alkali is a type of base.
Oxidation
An oxidation reaction involves gaining oxygen.
Oxidation reactions can also involve losing electrons.
Reduction
A reduction reaction involves losing oxygen.
Reduction reactions can also involve gaining electrons.
Oxidation in terms of electrons
When a substance is oxidised (gains oxygen), it always loses electrons.
Reduction in terms of electrons
When a substance is reduced (loses oxygen), it always gains electrons.
OIL RIG
Which non-metals are often included in the reactivity series of metals for reference?
Carbon, Hydrogen
Displacement order
A metal can only displace another metal from a compound if it is located above it in the reactivity series.
Potassium and water
Potassium is the most reactive so reacts very quickly.
The hydrogen produced ignites instantly and the metal also sets alight, sparking and burning with a lilac flame.
Sodium
Sodium fizzes rapidly and melts to form a ball that moves around on the water surface.
Lithium
Lithium fizzes steadily and floats, becoming smaller until it eventually disappears.
Metals that dont react with dilute acids
Copper, silver, gold and platinum.
Why is carbon used to extract metals?
Reducing a metal with carbon will result in the extraction of the metal if the metal is lower in the reactivity series than carbon.
Carbon is used because it is cheap and abundant
How is carbon used to extract metals
In the reduction, the metal oxide loses oxygen to form a pure metal.
Reduction with carbon normally involves heating the metal oxide in the presence of the carbon, which is often used in the form of coal.
When acids react with metals what is formed?
When acids react with metals, hydrogen and a salt are always formed
What are redox reactions
Redox reactions involve a reduction reaction (one reactant gains electrons) and an oxidation reaction (one reactant loses electrons)
What is a base
an alkali is a base that dissolves in water