The Reactivity Series

The Reaction of Metals with Dilute Acid.

Potassium, sodium, lithium and calcium all react violently
with dilute sulfuric acid and dilute hydrochloric acid.
It is dangerous to put these metals into an acid.
The reaction is similar to the reaction with water,
forming the metal salt (either sulfate or chloride) plus H2(g).

For example

sodium + hydrochloric acid    arrow   sodium chloride  +   hydrogen.
2Na(s)       +     2HCl(aq)      arrow            2NaCl(aq)      +      H2(g)

Magnesium, aluminium, zinc, iron, tin and lead
react safely with dilute acid.
Magnesium is the fastest and lead is the slowest of the six.

magnesium + sulfuric acid arrow magnesium sulfate + hydrogen.
Mg(s)    +    H2SO4(aq)     arrow       MgSO4(aq)     +         H2(g)

magnesium + hydrochloric acid arrow magnesium chloride + hydrogen.
Mg(s)       +   2HCl(aq)           arrow          MgCl2(aq)      +      H2(g)
(see rate)

aluminium + hydrochloric acid arrow aluminium chloride +  hydrogen.
2Al(s)       +       6HCl(aq)       arrow          2AlCl3(aq)      +      3H2(g)

zinc   sulfuric acid      arrow   zinc sulfate   +   hydrogen.
Zn(s)  +  H2SO4(aq)       arrow     ZnSO4(aq)      +        H2(g)

iron + hydrochloric acid  arrow   iron(II) chloride     +   hydrogen.
Fe(s)    +    2HCl(aq)     arrow         FeCl2(aq)         +         H2(g)

tin + hydrochloric acid  arrow    tin(II) chloride  +   hydrogen.
Sn(s)    +    2HCl(aq)    arrow        SnCl2(aq)         +        H2(g)

lead  sulfuric acid       arrow   lead sulfate   +   hydrogen.
Pb(s)  +  H2SO4(aq)      arrow      PbSO4(s)      +        H2(g)

The reaction of zinc with sulfuric acid is often used to
make a small amount of hydrogen in the laboratory - see moles
.
The reaction is slow at room temperature
but its rate can be increased by the
addition of a little copper(II) sulphate.
Zinc displaces copper metal, which acts as a catalyst.

Metals below hydrogen in the reactivity series
(copper, silver, gold and platinum) will not react with dilute acid.
They cannot displace hydrogen from the non-metal anion.
See displacement reactions (next page).

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