The **key difference** between dimensional analysis and stoichiometry is that **dimensional analysis is the conversion between an amount in one unit to the corresponding amount in the desired unit using various conversion factors whereas stoichiometry ****involves using relationships between reactants and/or products in a chemical reaction to determine desired quantitative data.**

The term dimensional analysis is very important in science, mainly in the field of physics. Stoichiometry, on the other hand, is important mainly in chemistry, regarding chemical reactions. Using stoichiometry, we can determine how much reactant reacted to give how much of the product.

### CONTENTS

1. Overview and Key Difference

2. What is Dimensional Analysis

3. What is Stoichiometry

4. Side by Side Comparison – Dimensional Analysis vs Stoichiometry in Tabular Form

5. Summary

## What is Dimensional Analysis?

Dimensional analysis is the conversion between an amount in one unit to the corresponding amount in a desired unit using various conversion factors. Moreover, the basic theory behind this is that physical quantities of the same nature have the same dimensions. Therefore, we can compare a set of physical quantities with another set of physical quantities having the same dimensions. For example, length is a physical quantity. If it is given in meters, we can compare it with another length even if it is given in yards or miles. We can make this comparison by converting meters into yards or vice versa. However, if the physical quantities do not have the same dimensions, we cannot compare them. For example, we cannot compare length with mass because they have different dimensions.

## What is Stoichiometry?

Stoichiometry is the quantitative relationships or ratios between two or more substances undergoing a physical change or chemical change. In this concept, we often deal with mass, volume and moles of substances. Furthermore, the uses of this concept are as follows:

- Balancing a chemical equation
- Converting grams into moles, vice versa
- Calculating molar masses of unknown substances
- Calculating molar ratios of chemical reactions

Let us consider an example to understand this concept. For the reaction A + 3B ⟶ C, reactants are A and B, which gives C as a product. Here, 3 molecules of B should react with one molecule of A to give one molecule of C. This is the stoichiometric relationship between the reactants and products. Moreover, if we know the amount of A reactant reacted with the B reactant to give C, we can find how much of the B reactant we need for this reaction. For example, if 10.0 grams of A reacted completely with some amount of B to give C, then we need to find the number of moles of A reacted so that we can find the amount of B that reacted with A (in moles). After that, we can find the mass of B using the molecular mass of the B, using the following equation;

n = m/M

where n is the number of moles, m is the mass reacted, and M is the molecular mass of the reactant.

## What is the Difference Between Dimensional Analysis and Stoichiometry?

Dimensional analysis is very important in physics, while stoichiometry is mainly important in chemistry. The key difference between dimensional analysis and stoichiometry is that dimensional analysis is the conversion between an amount in one unit to the corresponding amount in a desired unit using various conversion factors whereas stoichiometry involves using relationships between reactants and/or products in a chemical reaction to determine desired quantitative data. When considering the basic theory behind each concept, the theory behind dimensional analysis is that the physical quantities of same nature have the same dimensions while the theory behind stoichiometry is that the total mass of the reactants equals the total mass of the products.

## Summary – Dimensional Analysis vs Stoichiometry

The key difference between dimensional analysis and stoichiometry is that dimensional analysis is the conversion between an amount in one unit to the corresponding amount in a desired unit using various conversion factors whereas stoichiometry involves using relationships between reactants and/or products in a chemical reaction to determine desired quantitative data.

##### Reference:

1. Helmenstine, Anne Marie. “Stoichiometry Definition in Chemistry.” ThoughtCo, Jan. 6, 2019, Available here.

##### Image Courtesy:

1. “2280571” (CC0) via Pexels

## Leave a Reply