IGCSE Coordinated Science: Chemical and Physical Changes

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3.1 Chemical and Physical Changes

1 Identify physical and chemical changes, and understand the differences between them.

    Chemical Changes: These occur when a substance combines with another to form a new substance

     Examples include:

  • Rotting fruit
  • Mixing chemicals
  • Tarnishing silver.

    Physical changes: These are changes that affect the form of an object, but ultimately doesn’t have any effect on its chemical      composition.

Examples include:

  • Tearing a piece of tin foil.
  • Crumpling a piece of paper.

Differences  between the two:

1. A physical change is reversible, a chemical change is not. For example, the freezing of water would be a physical change because it can be reversed, whereas the burning of wood is a chemical change – you can’t ‘unburn’ it

2. A physical change is a change in which no new substance is formed; a chemical change results in the formation of one or more new substances. Again, consider the previous examples: Freezing water into ice just results in water molecules which are ‘stuck’ together – it’s still H2O. Whereas burning wood results in ash, carbon dioxide, etc, all new substances which weren’t there when you started.

You’re messing around with the physical structure object, but that’s it.


Click here to go to the next lesson: 3.2 Elements, Compounds and Mixtures


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7 Responses to IGCSE Coordinated Science: Chemical and Physical Changes

  1. Mackenzie says:

    Just a suggestion, but maybe you guys could make a terminology list. Considering for co-ordinated science there seem to be so many new words that we have to learn, and I find that if I have a vocabulary list of all the new words I have to learn it tends to help with my studying a lot.

    On a side not I love this website!

    • James Yang says:

      Hi Mackenzie, thank you very much for the suggestion. We will have glossary lists posted onto the Table of Contents page for iGCSE Science momentarily.

  2. Postnatalanxiety says:

    I have… I’VE ASKED THEM ALL…. NO ONE KNOWS WHO THE FATHER IS IVE GIVEN UP HOPE ON LIFE AND IM JUST DOING MY IGCSEs SOMEONE OUT THERE HELP ME! *sob* I dont have any more money for seeing any more experts my parents have thrown me out of my house and im working part time in a bar…. please… someone help me v.v

  3. Postnatalanxiety says:

    So saying you give birth to a baby and then
    a) You cut him up
    b) You heat his cut up body with some HCL

    which one of these are a chemical change and which one is a physical change and will I be caught if I flush this baby-acid mixture down the toilet

    • Firstly, I don’t suggest doing either of these things 😀

      a) He might become deformed, but essentially no chemical changes have occurred, so its a “Physical Change”.
      b) I think some combustion would occur if you heated him, but i’ve never tried, so I think you’re better off asking some experts 😀

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