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Year 11: Chemical Reactions 1.2

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  • Is this balanced: H₂ + O₂ → H₂O? Why?
    No. There are 2 oxygen atoms on the left but only 1 on the right.
  • What are products?
    The new substances formed in a reaction.
  • Give one sign of a chemical reaction
    Colour change Gas/bubbles Temperature change Solid forms
  • What does the small number in a formula mean? e.g
    How many atoms of that element there are.
  • Combustion needs = ?
    Oxygen.
  • Why does a yellow flame produce soot?
    There is not enough oxygen, so incomplete combustion occurs.
  • Atoms are rearranged in reactions - T/F?
    T
  • What is a chemical reaction?
    A process where substances change into new substances.
  • What is incomplete combustion?
    Burning with not enough oxygen.
  • What does H₂O mean? (what atoms are present?)
    2 hydrogen atoms and 1 oxygen atom.
  • Why does a candle go out under a jar?
    The oxygen runs out.
  • What happens to mass in a reaction?
    The total mass stays the same.
  • Mass can disappear in a reaction - T/F?
    F
  • O₂ = ?
    2 oxygen atoms / oxygen gas.
  • What happens to atoms in a reaction?
    They are rearranged into new substances.
  • What type of combustion can be seen using the yellow flame?
    Incomplete Combustion
  • Which type of combustion uses the blue flame on a bunsen burner?
    Complete combustion
  • CO₂ has 2 carbon atoms - T/F?
    F
  • Mass is = ?
    The amount of matter in something.
  • Atoms are = ?
    Tiny particles that make up substances.
  • Why do we balance equations?
    To show conservation of mass / same number of atoms on both sides.
  • What are reactants?
    The starting substances in a reaction.
  • Why mass stays the same in a reaction?
    Atoms are rearranged, not created or destroyed.
  • Why is CO dangerous?
    It stops oxygen being carried in the blood.
  • CO₂ = ?
    Carbon Dioxide
  • CO is safe to breathe - T/F
    F
  • Where does the mass go when something burns?
    Into gases released into the air.
  • CO =?
    Carbon Monoxide
  • What does CO₂ mean? (What atoms are present)
    1 carbon atom and 2 oxygen atoms
  • A yellow flame is complete combustion - T/F?
    F
  • What is combustion?
    A reaction where something burns in oxygen and releases energy.
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