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Chemistry Grade 6-8

Science: Types of Chemical Reactions

Identifying synthesis, decomposition, single replacement, double replacement, and combustion

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Practice recognizing common types of chemical reactions and describing what happens during each one.

Read each problem carefully. Identify the reaction type or explain what is happening in the reaction. Use complete sentences when needed.

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Identifying synthesis, decomposition, single replacement, double replacement, and combustion

Chemistry - Grade 6-8

Instructions: Read each problem carefully. Identify the reaction type or explain what is happening in the reaction. Use complete sentences when needed.
  1. 1
    Iron and sulfur combining into one dark product with a particle model of joined spheres.

    A reaction combines iron and sulfur to make iron sulfide: Fe + S -> FeS. What type of chemical reaction is this?

  2. 2
    A heated white solid breaking into powder and gas bubbles.

    Calcium carbonate breaks down when heated: CaCO3 -> CaO + CO2. What type of chemical reaction is this?

  3. 3
    A zinc strip in liquid producing bubbles, with particles showing one substance replacing another.

    Zinc reacts with hydrochloric acid: Zn + 2HCl -> ZnCl2 + H2. What type of chemical reaction is this?

  4. 4
    Two clear liquids mix and form a cloudy white precipitate as particles swap partners.

    Silver nitrate reacts with sodium chloride: AgNO3 + NaCl -> AgCl + NaNO3. What type of chemical reaction is this?

  5. 5
    Methane and oxygen enter a flame and form carbon dioxide and water molecules.

    Methane burns in oxygen: CH4 + 2O2 -> CO2 + 2H2O. What type of chemical reaction is this?

  6. 6
    Particles combining in one panel and a particle cluster breaking apart in another panel.

    Describe what makes a synthesis reaction different from a decomposition reaction.

  7. 7
    Green particles replace brown particles in paired molecules, leaving brown pairs separate.

    In the reaction Cl2 + 2KBr -> 2KCl + Br2, what type of reaction occurs, and which element is replaced?

  8. 8
    Two solutions combine, particles exchange partners, and a white solid settles out.

    In the reaction BaCl2 + Na2SO4 -> BaSO4 + 2NaCl, what type of reaction occurs?

  9. 9
    Hydrogen peroxide breaking down into liquid water and oxygen bubbles.

    Hydrogen peroxide breaks down into water and oxygen: 2H2O2 -> 2H2O + O2. What type of reaction is this?

  10. 10
    A magnesium ribbon burns in oxygen and forms white powder.

    Magnesium burns in oxygen to form magnesium oxide: 2Mg + O2 -> 2MgO. Name the reaction type and explain your choice.

  11. 11
    Oxygen involved in a flame on one side and rusting metal without flame on the other.

    A student says that every reaction with oxygen is combustion. Is that statement always correct? Explain.

  12. 12
    Heated crystals break down into a solid residue and escaping gas.

    Classify this reaction: 2KClO3 -> 2KCl + 3O2. Then explain what happens to the reactant.

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