Single Replacement

Related Examples and Practice Problems

Additional Worked Out Examples/ Practice

  • Identifying classification types: Differentiation between elements, compounds or mixtures and homogeneous and heterogenous mixtures

  • Separation techniques: Selected and explaining limitation of appropriate separation

  • Relating Properties to Composition: Predicting classification based on descriptive properties

Topic Summary & Highlights
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Core Concept

Single replacement reactions (also called single displacement reactions) involve one element replacing another in a compound. These reactions follow the general form: A+BC→AC+B

Where:

  • A is a single element.

  • BC is a compound.

  • A replaces B in BC if A is more reactive than B.

Practice Tips

  • Memorize Common Ions: Focus on learning the common polyatomic ions, charges, and patterns.

  • Roman Numerals for Transition Metals: Practice associating transition metals with their possible charges.

  • Cross-Method for Formulas: To determine the correct formula, use the “criss-cross” method to balance charges between cations and anions.

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Core Concept

Single replacement reactions (also called single displacement reactions) involve one element replacing another in a compound. These reactions follow the general form:

A+BC→AC+B

Where:

  • A is a single element.

  • BC is a compound.

  • A replaces B in BC if A is more reactive than B.

Types of Single Replacement Reactions

  1. Metal Replacing Metal:

    • A metal in its elemental form replaces another metal in a compound.

    • Example: Zn+CuSO4→ZnSO4+Cu\text{Zn} + \text{CuSO}_4 \rightarrow \text{ZnSO}_4 + \text{Cu}Zn+CuSO4​→ZnSO4​+Cu

  2. Metal Replacing Hydrogen:

    • A metal can replace hydrogen in acids or water (e.g., alkali metals reacting with water).

    • Example: Mg+2HCl→MgCl2+H2\text{Mg} + 2\text{HCl} \rightarrow \text{MgCl}_2 + \text{H}_2Mg+2HCl→MgCl2​+H2​

  3. Halogen Replacing Halogen:

    • A halogen in its elemental form replaces another halogen in a compound.

    • Example: Cl2+2KI→2KCl+I2\text{Cl}_2 + 2\text{KI} \rightarrow 2\text{KCl} + \text{I}_2Cl2​+2KI→2KCl+I2​

The Activity Series

The activity series is a list of metals and halogens ranked by their reactivity. In single replacement reactions, an element can replace another element in a compound only if it is higher on the activity series.

Key Points:

  • More reactive elements are at the top of the activity series.

  • Less reactive elements are at the bottom.

  • Metals at the top of the series (e.g., lithium, potassium) are highly reactive and can replace metals lower in the series.

  • Halogens also follow an activity trend, with fluorine being the most reactive.

Predicting Reactions Using the Activity Series

  1. Identify the Elements Involved:

    • Look at the single element (A) and the element it might replace in the compound (B).

  2. Check the Activity Series:

    • Find both elements in the activity series.

    • If A is higher on the activity series than B, the reaction will occur, and A will replace B.

  3. Write the Products:

    • Replace B with A in the compound to predict the products.

  4. If A is Lower:

    • If A is lower on the activity series than B, no reaction will occur.

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