How Should We Approach a Question of Stoichometry of Class 11th?

Chemistry is the branch of science concerned with the study of matter’s arrangement, structure, and characteristics. It is concerned with the study of changes in the production of various states of matter as a result of particular interactions.

Every aspect of chemistry begins with the fundamental concept of atomic particles and their interactions, but the most significant aspect is that chemistry also deals with steady-state elements that have already experienced specific reactions. In order to assess any reaction in terms of its reactants and products in a chemical reaction equation, it is critical to understand on what scale of amount the reaction is occurring, both in reactants and products. To comprehend such a notion, we must first learn the foundations of stoichiometry. Stoichiometry is a quantitative analogy based on the number of moles, which in this case refers to the mass of specific quantities involved in a chemical reaction, which are simply reactants and products. The law of conservation of mass is the foundation of stoichiometry. As a result, it may be argued that the total mass of the products must match the total mass of the reactants involved in a chemical process. If we could somehow empirically compute the measure of products in a case, and if one of the reactants in the chemical reaction can be determined, then the quantity of the other reactants in the chemical reaction can be determined as well. The following is an example of a chemical process that causes iron to rust:

4Fe +3CO₂           2Fe₂O₃

In the given chemical process, four moles of iron combine with three moles of carbon dioxide to produce two moles of ferrous oxide, or 2Fe₂O₃.

Stoichiometry, which is utilised to compute the measurement by mass or weight in a particular reaction indicated by a balanced chemical reaction equation, achieves the connection involving ratios of moles to corresponding atomic weights.

A stoichiometric ratio of a substance is the finest amount where, considering that the reaction has already undergone:

1. All the substance i.e., reactants have already been used.
2. There is no dearth of the reactants taking part in the chemical reaction.
3. There is also no surplus of the reagent.

The conversion of grams into equivalent amounts of moles using the idea of molar mass as the factor for conversion or from grams to millilitres using density is the most common usage of stoichiometry in chemistry. As an example, consider the following:

Let’s say you want to know how much sodium chloride, or NaCl, is in 2 grams. You’ll need to follow the steps below.

The units of grams are multiplicative in this case, therefore it is equal to (g/g=1), which produces the values in moles.

Molar Proportion

Well, stoichiometry is employed in balancing the chemical reaction equation as well as determining the conversion of grams to moles and vice versa. A basic example would be the combination of two diatomic gases, such as hydrogen and oxygen, to produce water, a liquid, resulting in an exothermic process.

2H₂ + O₂               2H₂O

The stoichiometry of the above process shows that the ratio of hydrogen, oxygen, and water molecules is 2:1:2.

Calculating the product quantity in a chemical reaction equation

Stoichiometry is also useful for calculating the amount of product released during a chemical process. For instance, if solid copper reacts with silver nitrate in its aqueous form in solution, the silver undergoes a displacement reaction, resulting in aqueous copper II nitrate and solid silver. The steps to analyse this would be as follows.

1. Putting the chemical reaction equation and balance it out.
2. Next step would be of conversion of mass of copper into the respective quantity of moles.
3. Further it is needed to find out the mole ratio i.e., moles of copper to that of the moles of silver yielded in a chemical reaction.
4. Finally, conversion of moles to mass i.e., finding out the number of moles of silver to the mass of silver produced.

Balanced chemical equation would be:

Cu +2AgNO₃Cu(NO₃)₂ +2Ag

Through its molecular mass, which in this case is 63.55g/mol, the mass of the coper is converted to moles of copper.

(16 gram of copper/1)(1 mole of copper/63.55 gram of copper)=0.2518 mole of copper

Determination of mole ratio i.e., copper to silver ratio

(0.2518 mole of copper/1)(2 mole of silver/1 mole of copper) = 0.503 mole of silver

Thus 0.503 mole of silver is produced, now the final step is to convert the silver in moles to silver in grams

(0.503 mole of silver/1)(107.87 gram of silver/1 mole of silver) = 54.32 gram of silver

Can you find the answer: LPG is a mixture of n-butane and iso-butane. The volume of oxygen needed to burn 1 kg of LPG at STP would be?