Chemistry, asked by vampireland123, 9 months ago

State and explain Avogadro's law.

Answers

Answered by wasifthegreat786

Answer:

Explanation:

Avogadro's law (sometimes referred to as Avogadro's hypothesis or Avogadro's principle) is an experimental gas law relating the volume of a gas to the amount of substance of gas present.[1] The law is a specific case of the ideal gas law. A modern statement is:

Avogadro's law states that "equal volumes of all gases, at the same temperature and pressure, have the same number of molecules."[1]

For a given mass of an ideal gas, the volume and amount (moles) of the gas are directly proportional if the temperature and pressure are constant.

The law is named after Amedeo Avogadro who, in 1811,[2][3] hypothesized that two given samples of an ideal gas, of the same volume and at the same temperature and pressure, contain the same number of molecules. As an example, equal volumes of molecular hydrogen and nitrogen contain the same number of molecules when they are at the same temperature and pressure, and observe ideal gas behavior. In practice, real gases show small deviations from the ideal behavior and the law holds only approximately, but is still a useful approximation for scientists.

Mathematical definition Edit

The law can be written as:

{\displaystyle V\propto n\,}V\propto n\,

{\displaystyle {\frac {V}{n}}=k}{\frac {V}{n}}=k

where

V is the volume of the gas;

n is the amount of substance of the gas (measured in moles);

k is a constant for a given temperature and pressure.

This law describes how, under the same condition of temperature and pressure, equal volumes of all gases contain the same number of molecules. For comparing the same substance under two different sets of conditions, the law can be usefully expressed as follows:

{\displaystyle {\frac {V_{1}}{n_{1}}}={\frac {V_{2}}{n_{2}}}}{\frac {V_{1}}{n_{1}}}={\frac {V_{2}}{n_{2}}}

The equation shows that, as the number of moles of gas increases, the volume of the gas also increases in proportion. Similarly, if the number of moles of gas is decreased, then the volume also decreases. Thus, the number of molecules or atoms in a specific volume of ideal gas is independent of their size or the molar mass of the gas.

Relationships between Boyle's, Charles's, Gay-Lussac's, Avogadro's, combined and ideal gas laws, with the Boltzmann constant kB =

n R

(in each law, properties circled are variable and properties not circled are constant)

Derivation from the ideal gas law Edit

The derivation of Avogadro's law follows directly from the ideal gas law, i.e.

{\displaystyle PV=nRT}PV=nRT,

where R is the gas constant, T is the Kelvin temperature, and P is the pressure (in pascals).

Solving for V/n, we thus obtain

{\displaystyle {\frac {V}{n}}={\frac {RT}{P}}}{\displaystyle {\frac {V}{n}}={\frac {RT}{P}}}.

Compare that to

{\displaystyle k={\frac {RT}{P}}}{\displaystyle k={\frac {RT}{P}}}

which is a constant for a fixed pressure and a fixed temperature.

An equivalent formulation of the ideal gas law can be written using Boltzmann constant kB, as

{\displaystyle PV=Nk_{\rm {B}}T}{\displaystyle PV=Nk_{\rm {B}}T},

where N is the number of particles in the gas, and the ratio of R over kB is equal to the Avogadro constant.

In this form, for V/N is a constant, we have

{\displaystyle {\frac {V}{N}}=k'={\frac {k_{\text{B}}T}{P}}}{\displaystyle {\frac {V}{N}}=k'={\frac {k_{\text{B}}T}{P}}}.

If T and P are taken at standard conditions for temperature and pressure (STP), then k′ = 1/n0, where n0 is the Loschmidt constant.

Historical account and influence Edit

Avogadro's hypothesis (as it was known originally) was formulated in the same spirit of earlier empirical gas laws like Boyle's law (1662), Charles's law (1787) and Gay-Lussac's law (1808). The hypothesis was first published by Amadeo Avogadro in 1811,[4] and it reconciled Dalton atomic theory with the "incompatible" idea of Joseph Louis Gay-Lussac that some gases were composite of different fundamental substances (molecules) in integer proportions.[5] In 1814, independently from Avogadro, André-Marie Ampère published the same law with similar conclusions.[6] As Ampère was more well known in France, the hypothesis was usually referred there as Ampère's hypothesis,[note 1] and later also as Avogadro–Ampère hypothesis[note 2] or even Ampère–Avogadro hypothesis.[7]

Experimental studies carried out by Charles Frédéric Gerhardt and Auguste Laurent on organic chemistry demonstrated that Avogadro's law explained why the same quantities of molecules in a gas have the same volume. Nevertheless, related experiments with some inorganic substances showed seeming exceptions to the law. This apparent contradiction was finally resolved by Stanislao Cannizzaro, as announced at Karlsruhe Congress in 1860, four years after Avogadro's death. He explained that these exceptions were due to molecular dissociations at certain temperatures, and that Avogadro's law determined not only molecular masses, but atomic masses as well.

Answered by CᴀɴᴅʏCʀᴜsʜ

Answer:◇ Avogadro's law is the relation which states that at the same temperature and pressure, equal volumes of all gases contain the same number of molecules. The law was described by Italian chemist and physicist Amedeo Avogadro in 1811.