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Acids, alkalis and salts - Coggle Diagram
Acids, alkalis and salts
Alkalis form alkaline solutions in water. Alkalis produce hydroxide ions, OH- in aqueous solution. For example:
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Neutral solutions
A neutral solution is neither acidic, nor alkaline. A neutral solution has a pH value of 7.
Acids form acidic solutions in water. Acids produce hydrogen ions, H+ in aqueous solution. For example:
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Neutralisation
A base is any substance that reacts with an acid to form a salt and water only. This means that metal oxides and metal hydroxides are bases.
Bases that are soluble in water are called alkalis and they dissolve in water to form alkaline solutions. For example:
copper oxide is a base, but it is not an alkali because it is insoluble in water
sodium hydroxide is a base, and it dissolves in water so it is also an alkali
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acids in solution are sources of hydrogen ions, H+
alkalis in solution are sources of hydroxide ions, OH-
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When acids react with metals, the products are a salt and hydrogen. In general:
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Magnesium, zinc and iron also react with sulfuric acid. The products are a salt (in this case a sulfate) and hydrogen. For example:
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Oxidation and Reduction
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Oxidation
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E.g. when metals react with oxygen, metal oxides are produced:
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When a substance is reduced (loses oxygen), it always gains electrons.
Reduction
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When a substance is oxidised (gains oxygen), it always loses electrons.
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Reactivity Series
When metals react with other substances, the metal atoms always form positive ions.
The easier it is for a metal to form its positive ion, the more reactive the metal is.
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Very unreactive metals, such as gold and platinum,
are found in the Earth’s crust as pure metals.
These are called native metals.
Displacement Reactions
A more reactive metal (one that forms positive ions more easily) can displace a less reactive metal from a compound. This is called a displacement reaction.
Displacement order
A metal can only displace another metal from a compound if it is located above it in the reactivity series.
Example
Magnesium is more reactive than copper, so magnesium can displace
copper from a copper sulfate solution to create magnesium sulfate.
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Platinum, however, is less reactive than copper and so cannot
displace copper from a copper sulfate solution.