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Why and How Do We Balance Chemical Equations

Okay, we know how chemicals react with each other and how reactants react and produce new stuff called products in chemistry jargon. This must mean understanding chemical reactions is a piece of cake. Simply write … Read More

how to balance the chemical equation

Okay, we know how chemicals react with each other and how reactants react and produce new stuff called products in chemistry jargon.

This must mean understanding chemical reactions is a piece of cake. Simply write the equation with reactants, draw an arrow and write products, right! Not quite! There’s a lot more to chemical reactions than meets the eye.

We call that “lot more” chemical equation balancing. Let’s bring in a little physics. You probably remember studying thermodynamics in your high school physics. Recall the 1st law of thermodynamics that states that energy is conserved in a closed system. 

Law of conservation of energy is not involved in chemical reactions in our context but its extension, the law of conservation of mass is definitely involved.

This is why we have to balance a chemical equation very carefully, and ensure that all the mass in reactants is retained in products.

Balancing equations is usually straightforward but gets a little bit complicated when radioactive decay is involved. In that case, you have to consider factors like half life calculator as well. 

If you do not balance the equation on paper, you can be rest assured that the reaction you wrote on your notebook doesn’t occur in nature. 

So how do we go about balancing a chemical reaction? Let’s explore the steps involved in balancing our chemical equation in detail. 

Steps

  • Have a look at both reactants and products in the chemical equation
  • Identify those chemicals that are in a single chemical species on both sides of the chemical equation.
  • See whether there’s a difference in the number of coefficients (atoms) on these compounds.
  • Place the corresponding number of coefficients (atoms) with the chemical compounds that have a difference

Now that we know how it’s done, let’s move to a practical example. 

Consider the following reaction.

CO2 + H2O = C6H12O6 + O2

The 1st move is to focus on elements that only show up once on each side of the equation. In the above equation, both carbon and hydrogen fit this criteria. 

So, let’s start with the carbon. There’s only one carbon atom on the left side, but 6 on the right side. So what we do is we add a coefficient of 6 on the carbon-containing molecule on the left side. Then we get,

6CO2 + H2O = C6H12O6 + O2

Now, let’s have a look at hydrogen. There are 2 hydrogen atoms on the left side and 12 on the right hand side. So, we add a coefficient of 6 on the hydrogen-containing molecule on the left side. then,

6CO2 + 6H2O = C6H12O6 + O2

Now, it is time we had a look at the oxygen. There are a18 total oxygen molecules on the left side (6×2 + 6×1). On the right however, there are only 8 oxygen molecules. 

Now, we are left with 2 options to even out the right side of the equation: We can either multiply C6H12O6 or O2 by a coefficient. 

Bear in mind though that if we alter C6H12O6, the coefficients for everything else on the left side of the equation will also have to be changed, because we’d be altering the number of carbon and hydrogen atoms. 

To avert this, it generally is handy to only alter the molecule composing of the fewest elements; in this case, the O2. So, we could add a coefficient of 6 to the O2 on the right. Our final answer would then be:

6CO2 + 6H2O = C6H12O6 + 6O2

And so, the equation is perfectly balanced.

Author: admin