4. Chemical Equations and Writing a Chemical Equation

We can express activity change in state as - when a magnesium ribbon is burnt in oxygen, it gets converted to magnesium oxide. This description of a chemical reaction in sentence form is quite long. It can be written in a shorter format. The most straightforward form to do this is to write it in the form of a word equation is

 

Magnesium + Oxygen → Magnesium oxide

        (Reactants)                        (Product)

 

The substances that support chemical change in the above reaction, magnesium and oxygen, are the reactants. The newly formed substance magnesium oxide is a product.

 

A word-equation shows the transformation of reactants to products by placing an arrow between them. The reactants are written on the left-hand side (LHS) and separated by a plus symbol (\(+\)). Furthermore, products are written on the right-hand side (RHS) and separated by a plus symbol (\(+\)). The arrowhead indicates the direction reaction by pointing to the products.

 

  

Is there any other shorter way of expressing chemical equations?

We can make chemical equations more concise and informative by using chemical formulae instead of words. A chemical equation expresses a chemical reaction. If you remember the formulae of magnesium, oxygen and magnesium oxide, the above word-equation can be written as -

 

\(Mg\) + \(O_2\) → \(MgO\)

 

Calculate and compare the number of atoms of each element on the LHS and RHS of the arrow. Is it correct that the number of atoms in each element is the same on both sides? If not, the equation is unbalanced because the masses on both sides of the equation are not the same. The skeletal chemical equation for a reaction is one such chemical equation. The above equation is a skeletal chemical equation for the burning of magnesium in the air.