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Avogadro’s Number Value: While solving numerical Physics and Chemistry one name that you must have encountered in Avogardo’s number. Most of you might be aware of its usage and value; if not, then refer to this explainer. Avogadro's number is a fundamental constant in chemistry and physics that represents the number of constituent particles (usually atoms or molecules) in one mole of a substance. To know more, read further.
Avogadro’s Number
From here, you will learn the basic details about Avogadro’s number that will help you during your exams to calculate the right answer.
Avogadro’s Number Definition
Avogadro’s number, denoted as NA, is defined as the number of constituent particles that include atoms, molecules, ions, etc. per mole of the substance. This helps in diving deep into the world of atoms and molecules and calculating them in grams and moles.
Avogadro’s Number Value
The accepted value of Avogadro's Number is approximately 6.022×1023 particles per mole. This value is an essential part of the International System of Units (SI) and is fundamental in defining the mole, which is the SI unit for the amount of substance.
Avogadro’s Number Meaning
Avogadro’s number is a bridge that fills the gap between the atomic or molecular scale and the macroscopic scale. It helps in knowing the number of atoms/molecules present in one mole of a substance. For example, in one mole of carbon atoms (12 grams of carbon), there are 6.022×1023 carbon atoms.
Avogadro’s Number Unit and Symbol
The unit of Avogadro's Number is particles per mole, often written as mol−1. The symbol used for Avogadro's Number is NA.
Avogadro’s Number Importance
Avogadro's Number is essential in various fields of science, including chemistry, physics, and biology. It allows scientists to quantify and relate the number of particles to measurable quantities such as mass and volume. This makes it possible to perform calculations that help in concluding the macroscopic observations.
Avogadro’s Number History
The concept is named after Italian scientist Amedeo Avogadro ((1776-1856), who proposed in 1811 that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules, regardless of their chemical nature and physical properties. Avogadro's hypothesis laid the groundwork for the development of Avogadro's Number as a fundamental constant.
Formulas With Avogadro’s Number
Some of the formulas in Chemistry and Physics that directly require Avogadro’s number are given here.
Chemistry:
- Molar Mass Calculation: Molar mass=Atomic or molecular mass×NA
- Example: The molar mass of water (H2O) is 18 u×NA.
- Number of Particles (Atoms/Molecules/Ions): Number of particles=Number of moles×NA
- Example: The number of atoms in 1 mole of carbon (12 grams of carbon) is NA.
Physics:
- Ideal Gas Law: PV=nRT
- P is pressure,
- V is volume,
- n is the number of moles,
- R is the gas constant,
- T is temperature in Kelvin.
Here, n is directly related to the number of gas molecules, n=N/NA where N is the number of molecules.
- Boltzmann Constant: kB=R/NA
Where kB is the Boltzmann constant and R is the gas constant.
- The relationship between the Faraday constant F and the elementary charge e: F=NAe
Example
Calculate the molar mass of oxygen gas (O2).
Solution:
- Atomic mass of oxygen (O) = 16 u (atomic mass units).
- Molar mass of O2 = 2 × atomic mass of O = 2 × 16 u = 32 u.
To find the molar mass in grams per mole, we use Avogadro's Number:
- Molar mass in grams per mole = 32 u × NA
- NA = 6.022×1023particles per mole.
So, molar mass of O2 = 32 u × 6.022×1023 particles per mole = 32×1.66054×10−24g
References and Further Reading
- Books
NCERT Class 10 Science Textbook PDF
NCERT Class 12 Physics Textbook PDF
- Articles
Magnetic effects of Electric Current
- Online Resources
CBSE Class 10 Science Video Tutorials
CBSE Class 12 Physics Video Tutorials
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