How is balanced chemical equation used in stoichiometry analysis? 

Actually, a chemical equation is used in stoichiometry analysis by balancing the equation, comparing the mole ratio and then solving to get the unknown substance required. 

Stoichiometry is defined as the quantitative study of the amount of reactants and products in a balanced chemical equation.

It is important to emphasize that stoichiometry calculations are usually hinged on balanced chemical equations. 

A chemical equation is the representation of a chemical reaction using symbols and formula.

Moreover, a balanced chemical equation shows equal number of atoms on both sides of the equation which is the basis for stoichiometry calculations.

Solving stoichiometry problems require balancing chemical equation as the first step and then following the guidelines in solving the problems.

While stoichiometry focuses on. quantitative calculations involving amount of reactants and products a balanced chemical equation shows the comparisons of the substances on both sides of equitation.

How can chemical equation be used to solve stoichiometry? 

We will show how chemical equations can be used to solve stoichiometry calculations by using few examples. 

Example 1 

If 3.5 moles of calcium carbonate was decomposed, calculate the number of moles of calcium oxide evolved? 


This question requires stoichiometry equation 

Step 1 

Build the stoichiometry equation 

CaCO3=== CaO + CO2 

Step 2 

Compare number of moles of known and unknown substance 

1 mole of CaCO3 == 1 mole of CaO 

3.5 moles of CaCO3 == X 

X= 3.5 X 1/ 1 = 3.5 moles of CaO 

You can agree with me that this stoichiometry problem is only possible with a balanced chemical equation. 

Example 2 

How many moles of Nitrogen would react with hydrogen to form 4.5 moles of ammonia? 


Step 1 

Build the equation 

N2 + 3H2 ===2NH3 

Step 2 

Compare the number of moles 

1 mole of N2===2 moles of NH3 

X mole of N2== 4 moles of NH3 

X= 1 mole X 4 moles /2 

X = 2 moles of Nitrogen 

Question 3 

What mass of Zinc chloride would be produced by reacting 3 moles of Zinc with Hydrochloric acid? 


Step 1 

Build the equation 

Zn +2HCl === ZnCl2 

Step 2 

Compare number of moles of known and unknown 

1 mole of Zinc === 1 mole of ZnCl2 

3 moles of Zinc== X 

X= 3 mole X 1 mole/ 1 mole 

X= 3 moles of Zinc Chloride 

Step 3 

Convert mole to mass 

1 mole of ZnCl2 ==136 grams 

3 moles if ZnCl2== X 

X= 3 X 186/1 

X= 558 grams of Zinc chloride 

Question 4 

What volume of hydrogen gas is evolved by 4.6 moles of magnesium reacting with Hydrochloric 



Mg + 2HCl === MgCl2 + H2 

1 mole of Mg === 1 mole of H2 

4.6 moles of Mg=== X 

X= 4.6 moles X 1 mole / 1 mole 

X= 4.6 moles of Hydrogen gas 

Recall that 

1 mole of gas at stp ==24 Litres 

4.6 moles of gas at stp == X 

X= 4.6 moles X 24 L/ 1 mole 

X= 110.4 Litres of Hydrogen gas 

Question 5 

What volume of oxygen would react with Carbon to form 5.5 litres of Carbon IV oxide? 


Step 1 

Build the equation 

C + O2 ===CO2 

Step 2  

Compare the moles of Known substance and unknown substance 

1 mole of carbon === 1 mole of Carbon IV oxide 

Step 3 

Change the moles to volume using molar volume 

24 litres of O2 === 24 litres of CO2 

X litres of O2 === 5.5 litres of CO2 

X = 24 litres X 5.5 litres / 24 litres 

X= 5.5 litres of Oxygen  

In conclusion , balancing chemical equation is the first step in stoichiometry analysis.

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