3.2 a/b/c: Reactions of Metals

Reactions of Metals

By Erin Hannan

​Syllabus dot points:

a	conduct practical investigations to compare the reactivity of a variety of metals in: – water – dilute acid – oxygen – other metal ions in solution
b	construct a metal activity series using the data obtained from practical investigations and compare this series with that obtained from standard secondary-sourced information
c	analyse patterns in metal activity on the periodic table and explain why they correlate with, for example: – ionisation energy – atomic radius – electronegativity

​What we will cover

• ​reactivity of metals

• activity series

• metals activity and the periodic table

​Reactions of metals

Poll

Which do you think are the 3 most reactive metals?

• Potassium

• Lithium

• Magnesium

• Calcium

• Zinc

​Activity Series

We use these reactivity scales to create a list of the metals in order of decreasing reactivity. ​

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• Hydrogen is often placed in the series to denote metals that do not displace hydrogen gas from dilute acid.

• Tells us: that a metal A will displace ​any metal B to the right of it in an aqueous solution of the ion of metal B.

• For example: Fe will displace Cu from a copper sulfate solution. ​

• Can use the data sheet for ​everything after Ca (the first few do not match up)

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Open Ended

Come up with a mnemonic for K, Na, Li, Ba, Ca

So you can remember their reactivity order (knowing you can use the data sheet for the rest)

Metal reactivity and the Periodic Table

• General trend = decreases left to right, increases top to bottom

• Correlates with first ionisation energy

  • only a guide, not a rigid rule

  • makes sense, losing an electron is what occurs when metals react with water, hydrogen, oxygen, and other metals

• ​as atomic radius increases, so does reactivity

  • electrostatic force will decrease, ​electrons are more easily lost

• as electronegativity increases, reactivity decreases

  • makes sense, opposite of first ionisation energy

​Displacement Reactions + equations

​A metal converts the ion of another metal to the neutral atom

E.g. ​when a more reactive metal displaces a less reactive element from a compound

​Can represent this with 3 types of equations:

1. ​Neutral species equation

   1. ​regular molecular/balanced equation

2. ​Complete ionic equation

   1. ​shows all the ions in solution

   2. solid stays as compound/a solid

3. Net ionic equation

   1. shows only the species participating in the reaction

   2. cancels out spectator ions ​

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​Example:

Solid zinc was placed in copper sulfate solution and left for an hour. ​

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Up Next:​

• Redox reactions

• Oxidation numbers

• Galvanic cells ​

Multiple Choice

Complete the general equation:

Metal + Acid ->

• Salt + Water

• Salt + Hydrogen

• Salt

Multiple Choice

Complete the equation:

Sodium + Hydrochloric Acid ->

• Sodium Hydroxide + Hydrogen

• Sodium Chloride + Hydrogen

• Chloric Sodium + Hydrogen

• Sodium Chloride + Water

Multiple Choice

Complete the equation:

Potassium + Nitric Acid ->

• Potassium Hydroxide + Hydrogen

• Potassium Chloride + Hydrogen

• Potassium Nitrate + Hydrogen

• Nitric Potassium + Hydrogen

Multiple Choice

When copper and magnesium sulphate are mixed together, there is no reaction. Why?

• Magnesium is more reactive than copper
• Copper is more reactive than magnesium
• Copper never reacts with metal salts
• Magnesium Sulphate never reacts with metals

Multiple Choice

Magnesium chloride + Sodium → ?

• Sodium chloride + Magnesium

• Magnesium chloride + Sodium (No change)

• Sodium magnesium + Chlorine

Multiple Choice

Lithium chloride + Iron → ?

• Lithium chloride + Iron (No change)

• Iron chloride + Lithium

• Lithium oxide + hydrogen

Multiple Choice

Zinc sulphate + Magnesium → ?

• Magnesium + Sulphur + Hydrogen

• Zinc sulphate + Magnesium (no change)

• Magnesium sulphate + Zinc

Multiple Choice

A displacement reaction will occur when...

• a more reactive metal displaces a less reactive metal from its aqueous salt solution.

• A less reactive metal displaces a more reactive metal from its aqueous salt solution.

• Displacement only occurs when two of the same metals are reacted

• Displacement reactions will only occur in metals above iron in the reactivity series

Multiple Choice

Which of the following is arranged according increasing reactivity?

• Mg > Li > Na > K
• Mg > Na > Li > K
• Na > Li > Mg > K
• K > Mg > Na > Li

Multiple Choice

Which is the correct net ionic equation for the reaction of AgNO₃ and CaCl₂?

• Ca²⁺(aq) +  2Cl^- (aq) → CaCl(s)
• Ag⁺(aq)  +  Cl^- (aq) → AgCl(s)
• Ag +  Cl  →  AgCl
• Ag⁺  +  Ca²⁺   →Ag₂Ca (s)

Multiple Choice

What are the spectator ions in the reaction of sodium chloride with silver nitrate?

• silver and nitrate
• sodium and chloride
• sodium and nitrate
• silver and chloride