SCH 3U
Unit: Chemical Reactions
Single Displacement Reactions
Types of Single Displacement Reactions
Name: ___________________________
Date: ___________________________
1)
A metal displaces another metal from an ionic compound
e.g. Zn displaces Fe in an oxide of Fe
3Zn(s) + 2Fe2O3(aq)  4Fe(s) + 3ZnO2(s)
2) A non – metal displaces another non – metal from an ionic compound
The non – metal chlorine displaces the non – metal bromine from the compound.
Cl2(g) + 2NaBr(aq)  2NaCl(aq) + Br2(l)
3) A metal displaces hydrogen from an acid or from water
The reaction of magnesium with hydrochloric acid releases hydrogen gas Mg(s) + 2HCl(aq)  H2(g) + MgCl2(aq).
Hydrogen can also be displaced from water however the hydrogen atoms in water are harder to displace than the
hydrogen atoms in an acid. This means that only very reactive metals can displace hydrogen gas from water (refer to
the activity series below). For example: 2Na(s) + 2H2O(l)  2NaOH(aq) + H2(g)
Using the activity series for metals
Determining Whether or Not A Single Displacement Reaction Will Occur
Type 1 Single Displacement
Reactions
Activity Series for Metals (and Hydrogen) (for use with Type 1 and Type 3 reactions from above) If the single metallic element in the
balanced chemical equation is
higher in the activity series than the
metallic element in the ionic
compound, then a reaction will
occur. The products will be the less
active metal, now written as an
element, and an ionic compound
composed of the more active metal
ion and the anion from the original
compound.
So, based on the activity series:
3Zn(s) + 2Fe2O3(aq)  4Fe(s) + 3ZnO2(s)
but,
4Fe(s) + 3ZnO2(s)  No Reaction
Type 3 Single Displacement
Reactions:
Every metal above hydrogen in the
activity series can displace
hydrogen gas from acids. Hydrogen
(gas) can also be displaced from
water, but only by the most active
metals as hydrogen atoms in water
are harder to displace than those in
acids.
So, based on the activity series:
Activity Series for Halogens (for use with Type 2 reactions from above)
Halogen
fluorine
chlorine
bromine
iodine
Reactivity
Most reactive
Least reactive
(McGraw – Hill Ryerson text):
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
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Do page 165 #1 – 5.
Do page 169, odd numbered questions.
Do page 170 #4, 5a, c, e, 7, 10, 11, 12, 13,
15b, d, f
2Na(s) + 2H2O(l)  2NaOH(aq) + H2(g)
Mg(s) + H2O(l) No Reaction
Mg(s) + 2HCl(aq)  H2(g) + MgCl2(aq)
Cu(s) + HCl(aq)  No Reaction
Using the Activity Series for Halogens
Single Displacement Type 2 Reactions: When one of the reactants is a
diatomic halogen molecule and the other reactant is an ionic compound
containing a different halogen, the halogen in the compound will be
displaced if the halogen in the diatomic molecule is higher on the activity
series than the halogen in the ionic compound.
So,
Cl2(g) + 2NaBr(aq)  2NaCl(aq) + Br2(l) because chlorine is higher on
the activity series than bromine, so chlorine displaces bromine in the
compound.
Br2(l) + 2NaCl(aq)  No Reaction because bromine is lower on the
activity series than chlorine.
Answers
Page 170 #7, 10, 11, 13 (all other homework question answers have solutions at the back of the book.
7.
Hydrogen is not a metal but it has a single valence electron like the metals in group 1 and is able to form 1+ ions. Because
hydrogen forms a positively charged cation, like metals do, rather than a negatively charged anion as non – metals usually
do, it is often involved in single displacement reactions with metals. When hydrogen is replaced by a metal, hydrogen gas,
H2(g) is produced. Single displacement reactions between hydrogen ions and metal ions to produce hydrogen gas involve
the hydrogen found in acids or in water. The hydrogen ions in water are harder to displace that the hydrogen atoms in an
acid so only very active metals can displace hydrogen from water.
10.
When a metal displaces hydrogen from water the reaction products are hydrogen gas and an aqueous solution of a metal
hydroxide.
Example: 2 Na(s) + 2 H2O  H2(g) + 2 NaOH(aq)
11.
As you go down group 17 (the halogens), atomic size increases so effective nuclear charge and electronegativity decrease.
These factors mean that as you go down group 17, the atoms become less likely to pull electrons closer to their nuclei and
therefore become less reactive.
13.
Any halogen below chlorine in group 17 on the periodic table can be replaced by chlorine in a single displacement
reaction.