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Single Displacement Reactions

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Students will be able to: Identify single displacement reactions Predict products for and balance single

displacement reactions Determine which single displacement

reactions actually occur

Learning Goals

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Students will be able to: Use the A + BC ⇒ B + AC symbolic formula

to identify a single displacement reaction and to determine products.

Use the Activity Charts to determine which single displacement reactions will proceed forward

Success Criteria

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Observe the following reaction: Copper + silver nitrate

What do you observe? What is the precipitate? What do you notice about the

solution?

Write a complete, balanced equation for this reaction.

Cu + AgNO3 Ag + Cu(NO3)2

Activity

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Is a reaction in which one element takes the place of another element in a compound

The products of a single displacement reaction are a new element and a new compound.

Single Displacement reactions occur between ionic compounds

Single Displacement Reaction

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A metal displacing another metal from an ionic compound

A and B represent metals, C is a non-metal

Types of Single Displacement Reactions

A B+ C A B+C

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A non-metal displacing another non-metal from an ionic compound

A represents a metal, B and C non-metals

Types of Single Displacement Reactions

A + B A + BC C

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Single displacement is similar to one man cutting in on another man at the dance

Dancing Analogy

At the start, dancer A is by himself and dancer B is dancing with dancer C. Dancer A “cuts in” on dancer B. In the end, dancer B is by himself and dancer A is dancing with dancer C

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Magnesium metal + lead (II) nitrate solution List your observations Write a chemical equation

Writing the Reaction

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zinc + lead (II) nitrate Zn + Pb(NO3)2 Pb + Zn(NO3)2

copper (II) nitrate + magnesium Cu(NO3)2 + Mg Mg(NO3)2 + Cu

*Lead + copper (II)nitrate Pb + Cu(NO3)2 Cu + Pb(NO3)2 (Pb2+ is more common)

*Iron + sulfuric acid Fe + H2SO4 H2 + Fe2(SO4)3 (Fe3+ is more common)

*remember to use the correct ion for multivalent metals. Your periodic table will tell you which is the more common “oxidation state”.

Find these metals and solutions and watch them react!

Now try these ones!

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How do we determine which elements can displace another?

Empirical evidence gathered through experimentation

Figure 1: (a) In the activity series of metals, each metal will displace the metal listed below it. Hydrogen is usually included in the series, even though it is not a metal, because hydrogen can form positive ions, just like the metal (b) The halogens can also be ordered in an activity series

(Nelson Chemistry 11 – p.126 Figure 3 and p. 127 Figure 4)

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Yesterday, you were given a more detailed activity series.

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For a reaction to occur, the element replacing the element within a compound MUST be more reactive

The lower the electronegativity of a metal element the more reactive it should be. We notice that the opposite is true for the halogens (higher electronegativity = more reactive). WHY??

Example 1: 2 Al(s) + Fe2O3(s)

Example 2: Zn(s) + Mg(NO3)2(aq)

2 Fe(s) + Al2O3(s)

NO REACTION

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Is gold reactive??

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1) aluminum + copper (II) nitrate ⇒ Aluminum is higher on the activity series than copper,

therefore a reaction takes place 2 Al + 3 Cu(NO3)2 ⇒ 3 Cu + 2 Al(NO3)3

We should see a coating of copper on the aluminum and the solution should turn from blue to colourless

2) iron + aluminum nitrate ⇒ Iron is lower on the activity series than aluminum,

therefore no reaction takes place Fe + Al(NO3)3 ⇒ NR The piece of iron should remain unaffected by the

solution

Which reaction will move forward?

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3) magnesium + hydrochloric acid ⇒ Magnesium is higher on the activity series than copper,

therefore a reaction takes place. Mg + 2 HCl ⇒ H2 + MgCl2 We should see bubbles of gas as hydrogen gas is

produced and the strip of magnesium slowly consumed. The solution remains colourless.

4) copper + hydrochloric acid ⇒ copper is lower on the activity series than hydrogen,

therefore no reaction takes place. Cu + HCl ⇒ NR The piece of copper should remain unaffected by the acid

Which reaction will move forward?

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5) tin + nickel (II) sulfate tin is lower on the activity series than nickel, therefore

no reaction takes place. Sn + NiSO4 ⇒ NR The piece of tin should remain unaffected by the

solution.

6) magnesium + iron (III) chloride magnesium is higher on the activity series than iron,

therefore a reaction takes place. 3 Mg + 2 FeCl3 ⇒ 2 Fe + 3 MgCl2 We should see iron precipitate onto the magnesium. The

solution should change from reddish-brown to colourless.

Which reaction will move forward?

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A + BC ⇒ C + BA Does a reaction occur? Use the Non Metal (Halogen) Activity Chart If so, predict the products. Balance the

equation if necessary.

Br2(aq) + NaI(aq)

Non-metals switching

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Can protect against corrosion by coating iron in a less reactive metal (example copper)

The statue of liberty was made out of iron, covered with insulation, and then coated with copper

Over time, the copper oxidized and the insulation wore away in places.

The more reactive iron then rusted when it came into contact with the copper (II) oxide. WHY?? The iron had to be replaced with stainless steel.

Corrosion and Protection

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The Galvanizing Process

A more reactive metal (zinc) is used to coat the iron. The zinc quickly reacts with oxygen to form zinc oxide (hard and insoluble). The zinc acts as a barrier to protect the iron underneath.

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Much of the world’s steel is galvanized for rust protection.

Stainless steel contains a significant portion of nickel and chromium

Galvanized Steel

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Water, especially salt-water, will corrode boat hulls.

So boaters place a strip of a more active metal on the surface of the boat – as a result the strip will corrode first and protect the rest of the hull

The strip is called a sacrificial anode because it is sacrificed in defense of the rest of the hull

Boats – Sacrificial Anode

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Metals are often removed from rock by using strong acid solutions.

Rocks are crushed into a fine slurry and added to tanks of acid.

The acids dissolve the metals from minerals and rocks.

The acids eventually transform into metal-rich solutions

How could you remove the metals from these solutions? (Hint: think about what you know about the activity series)

Mining

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Sheets of a metal higher on the activity series than Cu are placed in the copper solution. An electrical current speeds up the procedure

Removing copper from copper ore

Copper solution

Sheets of copper

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A single displacement reaction is a reaction where one element takes the place of another element in a compound.

Use the activity series to determine if a reaction will occur.

Review

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Complete the worksheet: Single Displacement Reactions Practice

Answer #1, 3, 5, 6 on pg. 128 of the textbook.

Practice