Lesson Worksheet: Thermal Decomposition Science

In this worksheet, we will practice describing and giving examples of thermal decomposition reactions.


Some of the following copper compounds can be thermally decomposed; others are thermally stable:

  • Cu(OH)2
  • CuBr2
  • CuCO3
  • CuSO4
  • CuCl2
  • CuO
  • CuS

Of those that decompose, which product is common in all cases?

  • ACu
  • BCuO2
  • CO2
  • DCuO
  • ECO2


Malachite is an impure ore used to form copper(II) oxide. The production of copper(II) oxide involves roasting the malachite in a large furnace at high temperatures. What chemical must be present in malachite to form copper(II) oxide during the reactions that take place inside the furnace?

  • ACopper(II) carbonate
  • BCopper chloride
  • CCopper(II) oxide
  • DCopper metal
  • ECopper sulfide


Which of the following reactions is an example of a thermal decomposition?

  • A2Al()+3Br()2AlBr()saqs23
  • B2Ca()+O()2CaO()sgs2
  • CHO()HO()+O()2222aqlg
  • DPbCO()PbO()+CO()32ssg
  • ECH()+2O()CO()+2HO()4222gggl


Which of the following chemical equations shows the thermal decomposition of zinc carbonate?

  • AZnCO()ZnO()+CO()32ssg
  • BZnO()+CO()ZnCO()sgs23
  • CZnC+O()2ZnO()+CO()222gsg
  • D2ZnO()+C()2Zn()+CO()sssg2
  • E2Zn()+O()2ZnO()sgs2


Which of the following products is formed during the thermal decomposition of copper(II) carbonate?

  • ACopper metal
  • BCopper(II) oxide
  • CWater
  • DHydrogen
  • ECarbon monoxide


A student placed a small quantity of zinc carbonate into a test tube. She weighed the test tube and zinc carbonate and found their mass to be 55 g. She then heated the test tube strongly for 5 minutes. After the test tube had cooled down, she reweighed it and the remaining powder inside.

What is the new mass of the test tube and zinc compound?

  • AMore than 55 g
  • BLess than 55 g
  • C55 g


Which of the following statements is correct?

  • AStatement 2
  • BStatement 4
  • CStatement 3
  • DStatement 1


A student heated a sample of lead carbonate in a test tube. He heated it until there was no further change, leaving a yellow solid in the test tube.

What type of chemical reaction occurred?

  • ACombustion
  • BOxidation
  • CThermal decomposition
  • DNeutralization
  • EDisplacement

Which gas was produced during this chemical reaction?

  • ACarbon monoxide
  • BSulfur dioxide
  • CSteam
  • DOxygen
  • ECarbon dioxide

What is the name of the yellow powder that remained in the test tube?

  • ALead carbonate
  • BLead nitrate
  • CLead metal
  • DLead chloride
  • ELead oxide

What is the word equation for this reaction?

  • ALeadcarbonateleadoxidecarbondioxidewater++
  • BLeadcarbonateleadoxygen+
  • CLeadcarbonateleadoxidecarbondioxide+
  • DLeadcarbonateleadcarbondioxide+
  • ELeadcarbonateleadoxideoxygen+


In the diagram, mercury oxide is being heated strongly to cause thermal decomposition. Which gas is being collected over water?

  • ASteam
  • BCarbon dioxide
  • CSulfur dioxide
  • DOxygen
  • ECarbon monoxide


The diagram shows the apparatus used to decompose a sample of lead carbonate.

What is the name of the liquid labeled X in the diagram, which is used to test for the presence of a gas given off during thermal decomposition?

  • AHydrochloric acid
  • BWater
  • CAmmonia solution
  • DLimestone water
  • ELimewater

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