Single Displacement Reactions and Acids

Single Displacement Reactions

• Definition: A single displacement reaction occurs when one element replaces another in a compound.
    - General Form:
      $A + BC(aq) <br>ightarrow AC(aq) + B$

• Common Examples:
    - Reactive metals displacing less reactive metals from solutions.
    - Reactive metals displacing hydrogen from acids.

Displacement of Metals from Metal Solutions

• Laboratory Practice:
    - Waste solutions containing silver ions should not be poured down the sink.
    - Such waste is collected and sent to commercial laboratories to recover silver from the nitrate solution by means of copper wire.

• Displacement Reaction:
    - A reaction wherein an element displaces another from a compound.
    - Example in context:
      - Copper displaces silver from silver nitrate solution.
      - Reaction:
        $ext{copper} + ext{silver nitrate solution} <br>ightarrow ext{silver} + ext{copper nitrate solution}$
      - Full equation:
        $ext{Cu(s)} + 2 ext{AgNO}_3(aq) <br>ightarrow 2 ext{Ag(s)} + ext{Cu(NO}_3)_2(aq)$

• Reactivity Series of Metals:
    - A ranking of metals based on their reactivity.
    - Used for predicting products of single displacement reactions.
    - Table 5.4 illustrates the reactivity series, where a more reactive metal displaces a less reactive one from its solution.
    - Example: If copper is placed in silver nitrate solution, copper will displace silver due to its higher reactivity.
      - The copper ions go into solution, causing the resultant bluish tint as depicted in Figure 5.17.
      - Silver ions are reduced to form silver metal.

• No Reaction Scenario:
    - If silver is placed in copper nitrate solution, no reaction occurs because silver is less reactive than copper.

Displacement of Hydrogen from Acids

• Acids Overview:
    - Commonly found both at home and in laboratories.
    - Corrosive Nature: Acids react with solid materials, often ‘eating’ them away.
    - Characteristic Features:
      - Sour taste (e.g., vinegar).
      - Some acids are dangerously corrosive (e.g., sulfuric acid in car batteries).
      - Other acids can be safe and pleasant (e.g., fruits).

• Strength of Acids:
    - Acids are classified as strong or weak based on their reactivity.
    - Strong Acids: React vigorously with metals and include:
      - Hydrochloric acid (HCl)
      - Sulfuric acid (H₂SO₄)
      - Nitric acid (HNO₃)
    - Weak Acids: Less reactive, such as:
      - Ethanoic acid (CH₃COOH)
      - Carbonic acid (H₂CO₃)
      - Phosphoric acid (H₃PO₄)

• Reactions of Metals with Acids:
    - These reactions exemplify displacement reactions where the products are a salt and hydrogen gas.
    - The activity series helps determine which metals can react with acids; metals higher than hydrogen in the series are capable of reacting.
    - More reactive metals produce more vigorous reactions with acids.

• Hydrogen Confirmation:
    - Pop Test:
      - Procedure: Collect hydrogen gas using an inverted test tube.
      - A lit match is introduced at the tube's mouth. A 'pop' sound confirms the presence of hydrogen, resulting from the reaction of hydrogen with oxygen:
        $2H_2(g) + O_2(g) <br>ightarrow 2H_2O(g)$

• Highly Reactive Metals:
    - Example: Sodium can displace hydrogen from water.

• Etymology of the Term 'Acid':
    - Derived from the Latin word acidus, meaning 'sour'.

Investigating Reactions of Acids with Metals

• Purpose:
    - To investigate the chemical interplay involving acids and various metals.

Quick Quiz (Sample Questions)

• Q1

• Q2

• Q3

• Q4

• Q5