Chemistry Revision

• How do we know a chemical reaction has taken place?

  Change of colour,

  gives off A gas,

  gets hot or cold,

  gives out light.
• What is a chemical reaction?

  It’s irreversible.
• What is a physical reaction?

  its reversible
• 3 things needed for a fire-

  Heat, fuel and oxygen
• Equation for complete combustion

  Fuel + oxygen = carbon dioxide + water + energy
• The equation for incomplete combustion

  Ethane + oxygen -> carbon monoxide + water
• what is oxidation?

  It’s when oxygen is added to a chemical in a reaction.
• What happens to the mass of metal when it is oxidised?

  It increases in mass
• What is thermal decomposition?

  It’s breaking down a substance using heat.
• What’s the word equation for thermal decomposition?

  Metal carbonate -> metal oxide + carbon dioxide.
• why does thermal decomposition lead to the mass decreasing?

  The carbon dioxide escapes to the air.
• what is a carbonate?

  is a compound that contains carbon and oxygen
• equation for a carbonate

  Carbonate + acid -> salt + water + carbon dioxide.
• What’s the test for carbon dioxide?

  Limewater
• What’s an example of a metal?

  Iron , copper, gold, silver.
• What’s an example of acid?

  Vinegar, citric acid, and hydrochloric acid.
• What’s the test for hydrogen gas?

  Squeaky pop
• What products are formed from a reaction of metal and acid?

  Salt + hydrogen
• What is precipitation?

  When two liquids are mixed together to form a solid substance.
• What does insoluble mean?

  It does not dissolve in a liquid.
• What does soluble mean?

  That it does dissolve in a liquid.
• How do you separate a solution with an insoluble liquid?

  Filter paper.
• What’s a nugget?

  Metals found in lumps already formed in the earth.
• What is an ore?

  A rock containing metal.
• How do you purify an ore?

  Smelting
• what does endothermic mean?

  Heat entering a reaction- feels colder.
• What does exothermic mean?

  Heat exiting a reaction- gives off heat.
• what reactions are exothermic?

  Combustion, oxidation
• What reactions are endothermic?

  Thermal decomposition
• What is a compound?

  A compound is made up of two or more types of atoms joined together by chemical bonds.
• What is a mixture?

  A mixture is made up of more than 1 type of element or compound.
• What is combustion?

  Combustion is burning.
• The smallest part of any substance is called an..

  Atom
• Equation for complete combustion

  Fuel + Oxygen = carbon dioxide + water + energy
• Equation for thermal decomposition

  Metal carbonate -> metal oxide + carbon dioxide
• The periodic table is organised into 3 sections- non metals, semi metals and metals. They are then arranged In order of increasing atomic number.