Curriculum
Course: Science — Second Preparatory
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Curriculum

Science — Second Preparatory

Unit 1: Matter and Energy

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Unit 2: Matter and Chemical Reactions

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Unit 3: Energy Flow in Photosynthesis and Respiration

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Unit 4: Geological Processes

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Text lesson

Chemical Reactions

Science — Second Preparatory

Chemical Reactions

Signs that a chemical reaction has happened

Signs that a chemical reaction has happened

  • We can tell that a chemical reaction has happened from the following observations:
Comparison aspectMain ideaKeywords
Colour change
  • for example
  • a cut apple turns brown when it is exposed to air
exampleappleturnsbrown
Gas produced
  • for example
  • vinegar bubbles when it reacts with sodium hydrogen carbonate
  • forming carbon dioxide bubbles
examplevinegarbubblesreacts
Precipitate formed
  • for example
  • a white solid forms when barium chloride solution is mixed with sodium sulfate solution
examplewhitesolidforms
Heat released or absorbed
  • for example
  • a pack becomes hot when water is added to quicklime
examplepackbecomeswater
Light produced
  • for example
  • magnesium burns with a bright white flame
examplemagnesiumburnsbright
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