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Difficulty: MediumChemical Reactions and Compounds

Chemical reactions can be grouped into distinct categories based on how atoms and ions are rearranged. Match each chemical reaction equation on the left with its correct classification type on the right. Which reaction type correctly pairs with each equation?

  • 2Mg+O2→2MgO2\text{Mg} + \text{O}_2 \rightarrow 2\text{MgO}Synthesis (combination) reaction
  • 2H2O2→2H2O+O22\text{H}_2\text{O}_2 \rightarrow 2\text{H}_2\text{O} + \text{O}_2Decomposition reaction
  • Cu+2AgNO3→Cu(NO3)2+2Ag\text{Cu} + 2\text{AgNO}_3 \rightarrow \text{Cu(NO}_3)_2 + 2\text{Ag}Single displacement (replacement) reaction
  • AgNO3+NaCl→AgCl+NaNO3\text{AgNO}_3 + \text{NaCl} \rightarrow \text{AgCl} + \text{NaNO}_3Double displacement (replacement) reaction

Answer

The magnesium burning equation pairs with synthesis, hydrogen peroxide breakdown pairs with decomposition, copper reacting with silver nitrate pairs with single displacement, and silver nitrate reacting with sodium chloride pairs with double displacement.
Each chemical reaction matches its structural pattern: synthesis creates one product from multiple reactants, decomposition breaks one reactant into multiple products, single displacement involves a free element displacing an ion from a compound, and double displacement involves two ionic compounds exchanging ion partners.

Step-by-Step Solution

1
Analyze the number and structure of reactants and products for the first equation (2Mg+O2→2MgO2\text{Mg} + \text{O}_2 \rightarrow 2\text{MgO}).
Two elemental reactants combine into one compound (A+B→ABA + B \rightarrow AB).
This matches the definition of a synthesis (or combination) reaction.
2
Analyze the second equation (2H2O2→2H2O+O22\text{H}_2\text{O}_2 \rightarrow 2\text{H}_2\text{O} + \text{O}_2).
A single compound reactant yields two distinct product molecules (AB→A+BAB \rightarrow A + B).
This matches the definition of a decomposition reaction.
3
Analyze the third equation (Cu+2AgNO3→Cu(NO3)2+2Ag\text{Cu} + 2\text{AgNO}_3 \rightarrow \text{Cu(NO}_3)_2 + 2\text{Ag}).
An uncombined element replaces an ion in a compound (A+BC→AC+BA + BC \rightarrow AC + B).
This is characteristic of a single replacement/displacement reaction.
4
Analyze the fourth equation (AgNO3+NaCl→AgCl+NaNO3\text{AgNO}_3 + \text{NaCl} \rightarrow \text{AgCl} + \text{NaNO}_3).
Two ionic compounds swap binding partners (AB+CD→AD+CBAB + CD \rightarrow AD + CB).
This is the hallmark of a double replacement/displacement reaction.

Key Concept

Classification of Major Chemical Reaction Types
Estimated Time:1m 0s
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Topics

Chemical Reactions and Compounds

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