• A?symbol?equation is a shorthand way of describing a chemical reaction using?chemical symbols?to show the number and type of each atom in the reactants and products
• A?word?equation is a longer way of describing a chemical reaction using only?words?to show the reactants and products

Balancing equations

• During chemical reactions, atoms cannot be?created?or?destroyed
• The number of each atom on each side of the reaction must therefore be the?same
  • E.g. the reaction needs to be?balanced

   

• When balancing equations remember:
  • Not to change any of the formulae
  • To put the numbers used to balance the equation?in front?of the formulae
  • To balance firstly the carbon, then the hydrogen and finally the oxygen in?combustion reactions?of organic compounds

   

• When balancing equations follow the following the steps:
  • Write the formulae of the reactants and products
  • Count the numbers of atoms in each reactant and product
  • Balance the atoms one at a time until all the atoms are balanced
  • Use appropriate state symbols in the equation

   

• The?physical state?of reactants and products in a chemical reaction is specified by using?state symbols
  • (s)?solid
  • (l)?liquid
  • (g)?gas
  • (aq)?aqueous

   

Answer:

Step 1:?Write out the symbol equation showing reactants and products

Mg + O2?→ MgO

Step 2:?Count the numbers of atoms in each reactant and product

Step 3:?Balance the atoms one at a time until all the atoms are balanced

2Mg + O2?→ 2MgO

This is now showing that 2 moles of magnesium react with 1 mole of oxygen to form 2 moles of magnesium oxide

Step 4:?Use appropriate?state symbols?in the fully balanced equation

2Mg (s) + O2?(g) → 2MgO (s)

Ionic equations

• In aqueous solutions ionic compounds?dissociate?into their ions
• Many chemical reactions in aqueous solutions involve ionic compounds, however only some of the ions in solution take part in the reactions
• The ions that do?not?take part in the reaction are called?spectator ions
• An?ionic equation?shows?only?the ions or other particles taking part in a reaction, and not the spectator ions

Answer 1:

Step 1:?To balance the equation, write out the symbol equation showing reactants and products

Zn? + CuSO4? → ZnSO4?+ Cu

Step 2:?Count the numbers of atoms in each reactant and product. The equation is already balanced

Step 3:?Use appropriate?state symbols?in the equation

Zn (s)? + CuSO4?(aq)? → ZnSO4?(aq) + Cu (s)

Answer 2:

Step 1:??The full chemical equation for the reaction is

Zn (s)? + CuSO4?(aq)? → ZnSO4?(aq) + Cu (s)

Step 2:??Break down reactants into their respective ions

Zn (s)? + Cu2+?+? SO42-?(aq)? → Zn2++ SO42-?(aq) + Cu (s)

Step 3:??Cancel the spectator ions on both sides to give the ionic equation

Zn (s)? + Cu2+?+?SO42-?(aq)? → Zn2++?SO42-?(aq) + Cu (s)

Zn (s)? + Cu2+(aq)? → Zn2+?(aq) + Cu (s)