the metals can be placed in order of reactivity by their reactions with water and dilute acid
potassium
sodium
lithium
calcium
magnesium
aluminium
zinc
iron
tin
lead
copper
silver
gold
hydrogen gas is given off if metals react with water or dilute acids.
the gas pops with a lit splint
1 of 8
C5.2: Displacement Reactions
a more reactive metal will displace a less reactive metal from its aqueous solution
the non-metals hydrogen and carbon can be given positions in the reactivity series on the basis of displacement reactions
oxidation is the loss of electrons
reduction is the gain of electrons
Oxidation Is Loss, Reduction Is Gain
2 of 8
C5.3: Extracting Metals
a metal ore contains enough of the metal to make it economic to extract. ores are mined and may need to be concentrated before the metal is extracted and purified
gold and other unreactive metals can be found in their native state
the reactivity series helps decide the best way to extract a metal from its ore
the oxides of metals below carbon can be reduced by carbon to give the metal element
metals more reactive than carbon must be extracted by electrolysis
3 of 8
C5.4: Salts from Metals
a salt is a compoud formed when the hydrogen in an acid is wholly or partially replaced by metal or ammonium ions
salts can be made by reacting a suitable metal with an acid
the metal must be above hydrogen in the reactivity series, but not dangerously reactive
the reaction between a metal and an acid produces hydrogen gas and a salt
a sample of the salt made can be crystallised by evaporating the water
the reaction between a metal and an acid is a redox reaction
the metal atoms lose electrons (oxidation) and the hydrogen ions gain electrons (reduction)
4 of 8
C5.5: Salts from Insoluble Bases
when an acid reacts with a base, a neutralisation occurs
the reaction between an acid and a base produces a salt and water
the sum of the charges on the ions equal 0
this enables you to work out the formula of salts (knowing the charges present)
a pure, dry sample of the salt made in an acid-base reation can be crystallised out of solution by evaporating off most of the water and drying with filter paper when needed.
5 of 8
C5.6: Making More Salts
an indicator is needed when a soluble salt is prepared by reacting an alkali and an acid
the experiment can be repeated without the indicator to make a salt, then a pure, dry sample of its crystals
a carbonate reacts with an acid to produce a salt, water and carbon dioxide gas
6 of 8
C5.7: Neutralisation and the pH Scale
acids are substances that produce H+(aq) ions when they are added to water
bases are substances which will neutralise acids
an alkali is a soluble hydroxide and alkalis produce OH-(aq) ions when added to water
the pH scale shows how acidic or alkaline a solution is
solutions with a pH less than 7 are acids, above 7 are alkaline and a pH of 7 is neutral
7 of 8
C5.8: Strong and Weak Acids
aqueous solutions of weak acids such as carboxylic acids have a higher pH value than solutions of strong acids with the same concentration
as the pH decreases by 1 unit, the hydrogen ion concentration increases by a factor of 10
Comments
No comments have yet been made