C4 (chemical changes) Flashcards
what happens when metals react with oxygen?
- when metals react with oxygen, they form a metal oxide.
- the metal atoms are oxidised (gains oxygen).
what is an oxidation reaction (includes oxygen)?
an element (usually a metal) gaining oxygen is called an oxidation reaction.
what is a reduction reaction (includes oxygen)?
an element (usually a metal) losing oxygen is called a reduction reaction.
what happens when you react a metal with water?
reacting a metal with water produces a metal hydroxide and hydrogen gas.
what occurs when metals react?
- they lose electrons and form a positive ion.
- the reactivity of a metal depends on its ability to lose electrons and form an ion. (i.e. potassium is more reactive and is more able to form a positive ion. copper is less reactive and the least able to form a positive ion).
how are different metals found in the Earth, based on their reactivity?
- unreactive metals, such as gold, are found in the Earth as the metal itself.
- most metals aren’t found pure. more reactive metals (e.g. iron), are found to have reacted with oxygen in the Earth’s crust, to form a compound (e.g. a metal oxide, iron oxide)
what is an ore?
a metal that can be extracted from a rock for profit.
what is a displacement reaction?
a more reactive element will push out (displace) a less reactive element from its compound.
what is an oxidation reaction (involves electrons)?
the loss of electrons.
what is a reduction reaction (involves electrons)?
the gain of electrons.
what is a redox reaction?
a reaction where both oxidation and reduction (in terms of electrons) occur at the same time.
- this is what occurs usually, as if one substance loses electrons, another has ro gain them.
what is the valence electron?
the outermost electron(s)
what are similarities amongst all acids?
- common acids include hydrochloric acid, sulfuric acid and nitric acid.
- all acids contain hydrogen (acid molecules ionise - split - and release H+)
- they’re all aqueous (can be dissolved in water).
- an H⁺ ion is an acid.
- they all have a pH less than 7.
what occurs when an acid reacts with a metal?
acid + metal = salt + hydrogen
what occurs when an acid reacts with a metal oxide/metal hydroxide?
metal oxide/hydroxide + acid = salt + water
- we take the negative ion from the acid, and combine it with the positive ion from the base, to create a salt. the leftover is then water.
THIS IS A NEUTRALISATION REACTION.
what occurs when an acid reacts with a metal carbonate?
metal carbonate + acid = salt + water + CO₂
how would you create a soluble salt?
react an acid with an insoluble base (e.g. metal oxide/hydroxide/carbonate)
THIS IS A NEUTRALISATION REACTION.
how do hydrochloric acid and sulfuric acid react with metals?
hydrochloric acid produces salts that end with ‘-chloride’.
sulfuric acid produces salts that end with ‘-sulfate’.