Curriculum
Science — Second Preparatory
Unit 1: Matter and Energy
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Unit 2: Matter and Chemical Reactions
0/6
Unit 3: Energy Flow in Photosynthesis and Respiration
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Unit 4: Geological Processes
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Text lesson
The Chemical Equation
The Chemical Equation
Balancing a chemical equation
Balancing a chemical equation
- An equation is balanced when the number of atoms of each element is the same on both sides.
- This follows from the law of conservation of mass.
- The steps are:
- Write the equation with the correct formulas for the reactants and the products.
- Count the atoms of each element on both sides.
- Place coefficients in front of the formulas to make the numbers equal, starting with an element whose numbers do not match.
- Check every element again.
- Example balance Mg + O₂ → MgO. There are 2 oxygen atoms on the left and 1 on the right, so we place 2 in front of MgO to get 2MgO. Now there are 2 magnesium atoms on the right, so we place 2 in front of Mg. The balanced equation is 2Mg + O₂ → 2MgO.
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