Activity series
Experiment # 15
What we are doing today:
• We are going to test reactions of metals with acids
• We are going to test single replacement reactions.
•We are going to determine a relative activity series BASED
ON OUR EXPERIMENTAL DATA
9F Reactivity in chemistry
What does reactivity mean?
Elements that are reactive readily take part in
reactions with other chemicals.
But an element might react very quickly with one chemical
and hardly at all with another. So is it reactive or not?
To compare the reactivity of different elements,
we might see how easily they react with oxygen.
Some metals corrode in
minutes out on the bench.
Others take longer to corrode,
unless you heat them.
9F The Gold Cup again?
We can list metals
in order of how
quickly they react
with oxygen.
This ranking of
metals according
to reactivity is
called the
reactivity series.
most reactive
least reactive
speed of reaction with oxygen
9F Reaction of metals with acid
What if we react different metals with acid?
copper
iron
lead
magnesium
sodium
–– the
the
–– no
the
metal
metal
–bubbles,
metal
the
reacts
reacts
metal
bursts
no
slowly,
very
reacts
reaction
into
slowly,
producing
flames,
quickly
with
producing
acid
with
a very
a few
thestrong
very
bubbles
acid,few
reaction
bubblesproducing lots of bubbles
9F What about water?
We can also rank metals by their reaction with water.
Compare with the reactivity series for oxygen and acid.
reactivity series with
oxygen
acid
water
potassium
sodium
magnesium
zinc
iron
lead
copper
gold
potassium
sodium
magnesium
zinc
iron
lead
copper
gold
potassium
sodium
magnesium
zinc
iron
lead
copper
gold
The reactivity series is very useful. How can we learn it?
9F Remembering the series
metal
potassium
sodium
magnesium
aluminium
zinc
iron
lead
hydrogen
copper
gold
symbol
K
Na
Mg
Al
Zn
Fe
Pb
H
Cu
Au
useful mnemonic?
Kangaroos
Naturally
Muck
About in
Zoos
For
Purple
Hippos
Chasing
Aardvarks
Come on, you can think of a better mnemonic!
9F Using the series
The reactivity series allows you to make predictions.
Choose from the box below. What will happen when you mix...
...a metal
…and an acid?
potassium
hydrochloric acid
very violent reaction
magnesium
hydrochloric acid
fast reaction
iron
hydrochloric acid
gas bubbles form slowly
copper
hydrochloric acid
nothing happens
gold
hydrochloric acid
nothing happens
nothing happens
fast reaction
very violent reaction
gas bubbles form slowly
nothing happens
9F Feeling a bit displaced?
A single replacement reaction
happens when one metal replaces
another one in a compound.
Magnesium is more reactive
than copper.
Magnesium displaces copper
from copper sulphate solution.
magnesium + copper sulphate
magnesium sulphate + ?
9F A model for displacement reactions
This model will help explain displacement reactions.
Think of reactivity as aggression!
Write a word equation for this reaction.
Part A
• To six test tubes add approximately 0.5 ml
of HCl
• Add a small piece Ca metal to the test tube
• Record all changes
• Repeat for all five metals
• Write complete and ionic equations for each
metal
Part B
• To one test tube add approximately 0.5 ml of a
polyatomic ionic compound Ca(NO3)2
• Repeat for each of the other six polyatomic ionic
compounds
• Add a small piece Ca metal to each test tube
• Record all changes
• Repeat for all five metals
• Write complete and ionic equations for each metal
Part B
• Dispose of the waste and Repeat all
procedures for each of the other five metals
• Write complete and net ionic equations for
each metal
Part C
Based on your experimental data determine a relative activity
series of the metals in question
Ca
Cu
Fe
Mg
Sn
Zn
Al
Types of chemical equations
Equations can be divided into 3 types
1) Molecular, 2) Ionic, 3) Net ionic
• Here is a typical molecular equation:
Cd(NO3)2(aq) + Na2S(aq)  CdS(s) + 2NaNO3(aq)
• We can write this as an ionic equation
• (all compounds that are (aq) are written as
ions):
Cd2+(aq) + 2NO3–(aq) + 2Na+(aq) + S2–(aq)
 CdS(s) + 2Na+(aq) + 2NO3–(aq)
Net Ionic equations
Cd2+(aq) + 2NO3–(aq) + 2Na+(aq) + S2–(aq)
 CdS(s) + 2Na+(aq) + 2NO3–(aq)
• To get the NET ionic equation we cancel out
all terms that appear on both sides:
Net:
Cd2+(aq) + S2–(aq)  CdS(s)
Equations must be balanced
• There are two conditions for molecular, ionic,
and net ionic equations
Materials balance
Both sides of an equation should have the
same number of each type of atom
Electrical balance
Both sides of a reaction should have the same
net charge
Due next week
• Pg 167 and 168
• Need to show all work for full credit!!