# chemical equations 1 yr 10 mocks

- Created by: tia5303
- Created on: 15-07-20 16:38

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- 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
- methane + oxygen ---> carbon dioxide+ water
- the molecules on the right hand side are called the products

- the molecules on the left hand side of the equation are called reactants.

- 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 cant change formulas like H SO to H SO
- you can only put numbers in front of them

- the formulas are all correct but the number of atoms don't match up on both sides

- H SO + NaOH -----> Na SO + H O

- take this equation for reacting sulfuric acid with sodium hydroxide:

- you balance the equation by putting numbers in front of the formulas where needed.

- there must always be the same number of atoms on both sides of the equation
- 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

- the formulas are all correct but the number of atoms don't match up on both sides

- H SO + NaOH -----> Na SO + H O

- need to be balanced !!!

- you balance the equation by putting numbers in front of the formulas where needed.

- there must always be the same number of atoms on both sides of the equation
- 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:

- 3) carry n chasing unbalanced elements and the equation will sort itself out in no time

- 2) see where that gets you. It may create another imbalance, if so, pencil in another number and see where it gets you.

- 1) find an element that doesn't balance and pencil in a number to try and sort it out.

- need to be balanced !!!
- 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

- they tell you what physical state the reactants and products are in

- symbol equations can also include state symbols next to each substance
- 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:

- anything that's exactly the same on both sides of the equation can be left out.

- 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

- on way to show a chemical reaction is to write a word equation.

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