chemical equations 1 yr 10 mocks


?
  • Created by: tia5303
  • Created on: 15-07-20 16:38
View mindmap
  • chemical equations
    • on way to show a chemical reaction is to write a word equation.
      • however its not as useful as using chemical symbols because you cant tell straight away what's happened to each of the atoms. It's easy.
      • heres an example - methane burns oxygen giving carbon dioxide and water:
        • the molecules on the left hand side of the equation are called reactants.
          • methane + oxygen ---> carbon dioxide+ water
            • the molecules on the right hand side are called the products
        • methane + oxygen ---> carbon dioxide+ water
          • the molecules on the right hand side are called the products
    • symbol equations
      • need to be balanced !!!
        • there must always be the same number of atoms on both sides of the equation
          • you balance the equation by putting numbers in front of the formulas where needed.
            • need to be balanced !!!
              • there must always be the same number of atoms on both sides of the equation
                • you balance the equation by putting numbers in front of the formulas where needed.
                  • take this equation for reacting sulfuric acid with sodium hydroxide:
                    • H SO + NaOH -----> Na SO + H O
                      • the formulas are all correct but the number of atoms don't match up on both sides
                        • you cant change formulas like H  SO  to H  SO
                          • you can only put numbers in front of them
                      • you cant change formulas like H  SO  to H  SO
                        • you can only put numbers in front of them
            • take this equation for reacting sulfuric acid with sodium hydroxide:
              • H SO + NaOH -----> Na SO + H O
                • the formulas are all correct but the number of atoms don't match up on both sides
        • steps to balancing a symbol equation
          • 1) find an element that doesn't balance and pencil in a number to try and sort it out.
            • 2) see where that gets you. It may create another imbalance, if so, pencil in another number and see where it gets you.
              • 3) carry n chasing unbalanced elements and the equation will sort itself out in no time
                • example below:
      • state symbols tell you the state of a substance in an equation
        • symbol equations can also include state symbols next to each substance
          • they tell you what physical state the reactants and products are in
            • (s) - solid
            • (l) - liquid
            • (g) - gas
            • (aq) - aqueous
      • ionic equations show the useful bits of reactions
        • in an ionic equation only the reacting particles ( and the products they form) are included
        • to write an ionic equation you have to look at the reactants and products.
          • anything that's exactly the same on both sides of the equation can be left out.
            • example:
      • half equations show the movement of electrons
        • half equations show how electrons are transferred during reactions.
        • e- stands for one electron
        • you cant write half equations for all chemical reactions - only the ones where oxidation or reduction happen.
        • examples:
          • you cant write half equations for all chemical reactions - only the ones where oxidation or reduction happen.
        • you can combine half equations to create full ionic equations
        • full equations never contain electrons - the electrons in the reactants and products should cancel out
          • so in the sodium/hydrogen example (highlighted pink), the full ionic equation would be : 2Na + 2H  --> 2Na  + H

    Comments

    No comments have yet been made

    Similar Chemistry resources:

    See all Chemistry resources »See all Calculations, moles and yield resources »