GCSE Chemistry -Balancing Equations

DinuStarred Page By Dinu, 11th Aug 2011 | Follow this author | RSS Feed | Short URL http://nut.bz/1_ddt3k7/
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Having trouble balancing chemical equations or do you find it hard? this page will help you to balance chemical equations easily. Everyone is welcome to read! You don't have to be a student, you can be a parent who wants to help their child, go through this page and you can help your child with their homeworks

Balancing Equations part 1

Before we start balancing equations, we need to look at the word equation first:
For example;
Sodium + Oxygen -------> Sodium oxide
Now you can write the symbol equation underneath;
Na(s) + O2(g) ------> Na2O(s)
In some exam questions they ask you to write state symbols for the equation so I have written the equations with out state symbols;
State symbols means whether the reactants and products are solid (s), liquid (l), gas (g) or aqueous (aq). So the state symbol for each is shown in the brackets.
Note: Aqueous means dissloved in water/contain water

The formula for sodium oxide is Na2O. This means there are 2 sodium atoms bonded to 1 oxygen atom

Step 1:

  • Show the equation using coloured circles to represent each different atom.
  • I’ve used blue to represent sodium and red for oxygen (as shown in the picture).

Step 2:

  • Count the number of each type of atoms on the left-hand side (reactants) and on the right-hand side (products)
  • Write them down in a table as shown in the picture (makes it easier to read).

Step 3: how do we balance it?

As you can see the equation is not balanced, so now we choose one type of atom to balance primarily.

Note: it is best to choose an ODD number atom, i.e. there is 1 oxygen atoms in the product.

So we choose Oxygen. Now, there are 2 oxygen atoms on the LHS so we also need 2 Oxygen atoms on the RHS to balance out. We simply multiply the number of Sodium oxide (Na2O) molecules by 2

Na(s) + O2(g) ----> 2Na2O(s)

Now the number of oxygen atoms on both sides is balanced. BUT the number of sodium atoms is still different. As you can see there are 4 sodium atoms on the RHS and 1 sodium atom on the LHS so we need to multiply LHS sodium (Na) by 4.
Note: You might find it easier if you write the equation again using coloured circles once you have balanced one type of atom.


4Na(s) + O2(g) ------> 2Na2O(s)

Now we have the same number of Sodium atoms and Oxygen atoms on each side. There, the equation is balanced!

Summary of steps:

  1. Use coloured circles to represent the different atoms.
  2. Count the number of each atoms on each side.
  3. Choose One type of atoms and balance it first
  4. Then choose another to balance until all the atoms are balanced

Questions for you to have a go at -simple questions

Note: I only used a dashed arrow because the formatting doesn’t allow me to use normal arrows, YOU HAVE TO USE NORMAL ARROWS when you write these equations.

  1. Potassium + Oxygen -------> Potassium oxide
  2. K(s) + O2(g) ------> K2O(s)

  3. Lithium + Oxygen -------> Lithium Oxide
  4. Li(s) + O2(g) ------> Li2O(s)

  5. Sodium + Water -----> Sodium Hydroxide + Hydrogen
  6. Na(s) + H2O(l) -----> NaOH(aq) + H2(g)

  7. Potassium + Water -----> Potassium Hydroxide + Hydrogen
  8. K(s) + H2O(l) -------> KOH(aq) + H2(g)

  9. Sodium + Chlorine -----> Sodium Chloride
  10. Na(s) + Cl2(g) -------> NaCl(s)

  11. Sodium + Bromine ------> Sodium Bromide
  12. Na(s) + Br2(g) ------> NaBr(s)

  13. Sodium + Iodine ------> Sodium iodide
  14. Na(s) +I2(g) -------> NaI(s)

  15. Magnesium + Oxygen -----> Magnesium oxide
  16. Mg(s) + O2(g) -----> MgO(s)

Questions for you to have a go at- Harder questions

Note:If a molecule contains more than one atom of a particular element, this quantity is indicated using a subscript after the chemical symbol as shown in the picture.(I've written it as MgCO3 because I couldn’t find the correct formatting tools)

  1. MgCO3 + HCl -----> MgCl2 + H2O + CO2

  2. CuO + HBr -----> CuBr2 + H2O

  3. NaOH + H2SO4 -----> Na2SO4 + H2O

  4. NaOH + AlBr3 ------> NaBr + Al(OH)3

  5. NH3 + O2 ------> NO + H2O

  6. Fe + O2 -------> Fe2O3

  7. Fe2O3 + CO ------> Fe + CO2

  8. N2 + H2 ------> NH3

Answers

Before you look at the answers, have a go at these quations by yourselves.
Follow the link below to see the answers.
Okay, Here's the answers

If you have any questions or any requests regarding GCSE Chemistry then just comment them on this page and I’ll answer :)

Tags

Balancing Equations, Chemical Reations, Chemistry, Gcse, Symbol Equations

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author avatar Dinu
I have written few short stories (fictions) and I love writing to the extent where i can't write enough to satisfy myself.

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