Reactivity Series

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Reactivity Series

• Metals

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Objectives

• That this order is called the Reactivity Series
• That in the reactivity series the most reactive
  metal is at the top
• That the more reactive metals can displace the
  less reactive (including hydrogen)
• That the series an predict reactions and the
  extraction method
• To know the metals can be written in an order of
  reactivity

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Reactivity Series
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Reaction with acids
Hydrogen gas from the reaction of magnesium metal
with acid
When magnesium metal is treated with acid
evolution of hydrogen gas results
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Concepts

• Single Replacement Reactions

• A BC ? AC B

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How?
The weak are displaced by the strong!
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Single Replacement Reactions

• A single replacement reaction is of the general
  form
• A BC ? AC B
• In order for a single replacement reaction to
  occur, A must be more reactive than B in order to
  combine with C
• In this reaction
• Mg (s) 2HCl (g) ? MgCl2 (aq) H2(g)
• Since the reaction occurs, we must conclude that
  magnesium is more reactive than hydrogen

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Metal displacement
Cu(s) 2AgNO3 (aq) ? Cu(NO3)2 (aq)
2Ag(s) Coppersilver nitrate ?copper nitrate
silver

• Copper is higher than silver in the Reactivity
  Series.
• Copper can displace silver from it silver
  compounds (e.g. silver nitrate)

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Objectives

• To observe a chemical reaction between a metal
  and an acid
• To measure rate of hydrogen gas produced
• To consider the factors which can affect
  reactions rates

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Checkpoint

• a) Zn (s) Cu(NO3)2 (aq) ?
• zinc copper nitrate ?
• b) Ca (s) 2H2O (l) ?
• calcium water ?
• Mg (s) AgNO3 (aq) ?
• magnesiumsilver nitrate ?
• Cu (s) H2SO4(aq) ?
• copper sulphuric acid ?

• Zn(NO3)2 (aq) Cu (s
• zinc nitrate copper
• Ca(OH)2 (aq) H2(g )
• calcium hydroxide hydrogen
• Mg(NO3)2 (aq) Ag(s)
• Copper nitrate silver
• No reaction

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Magnesium acid

• Hydrogen evolution began as soon as the magnesium
  metal was added to the water
• The hydrogen was less dense than water so it rose
  through it
• The hydrogen gas was able to be collected in a
  burette or gas syringe

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Reaction Rates

• Magnesium hydrochloric acid

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But how fast?
Displaced air
Gas syringe
hydrogen
Hydrochloric acid
magnesium
Note volume of hydrogen produced volume of
displaced air
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Typical Results
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Graph
Gradient initial rate of hydrogen production
volume of hydrogen 50 13
cm3/min time 3.6
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Graph shape
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Collisions
For a reaction to occur the reactant molecules
must collide with enough energy (the activation
energy) to react.
On collision the reactant molecule re-arrange to
form product molecules
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Factors which can affect reaction rates

• Concentration how crowded the solution is,
  higher concentrations increase the chance of a
  collision
• Temperature affects the speed molecules are
  moving and the energy available to break bonds on
  collision
• Surface area how big a target the moving
  particles have to hit
• Catalyst speeds up the reactions by lowering
  the energy needed to break bonds.

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Concentration
At higher concentrations there is more chance of
a collision so more chance of a reaction taking
place.
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Temperature
cold
hot
At higher temperatures there are more collisions
with enough energy for a reaction to take place
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Surface area
Block
Same block broken into 8
Which has the larger surface area, the block or
the same size block broken? Which has the larger
surface area? Which will increase the chance of a
collision and therefore a faster reaction rate?
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Which has the most surface area?
Each of these represents 10g of limestone
A
B
C
Which has the largest surface area? Which will
react with acid the fastest?
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Catalyst
Catalysts speed up a reaction. They do this by
making it easier for bonds to be broken in the
reactants so new bonds can be made in the
products. A catalyst does this by lowering the
energy to break bonds, they lower the activation
energy. This leads to more successful collisions
per second so a faster reaction rate