Question

In 2019, the mole was redefined to be exactly

6.02214076×10²³elementary entities. This redefinition means that the mass of one mole of Carbon-12 is no longer exactly 12 grams. Avogadro's number (Nₐ) was originally defined as the approximate number of carbon-12 atoms in 12 grams of pure carbon-12 isotope. With the redefinition,(Nₐ) is now exactly 6.02214076×10 ²³ mol⁻¹. Avogadro's number is not calculated; it is defined by the relationship
N ₐ=μ/Mu​, where Mu is the molar mass constant and mu is the atomic mass constant.
The molar mass constant (Mu) is currently defined as 1.66053906660(50)×10⁻²⁷ kg.
The atomic mass constant (mu) is currently 0.99999999965(30)×10⁻³kg⋅mol⁻¹. The uncertainty in element molar masses is typically larger than the shift due to the Avogadro number redefinition. This is primarily due to fluctuation in isotope abundances.
Elements with a single natural isotope have molar masses with uncertainties comparable to the shift from the Avogadro number redefinition.

Answer 1

A mole is a unit of measurement in chemistry that represents a specific amount of a substance. Avogadro's number is the number of molecules or atoms in one mole. The redefinition of the mole in 2019 means that the mass of one mole of carbon-12 is no longer exactly 12 grams.

Step-by-step explanation:

A mole is a unit of measurement in chemistry that represents a specific amount of a substance. It is defined as the amount of any substance that contains as many molecules or atoms as there are atoms in exactly 12 grams of carbon-12. Avogadro's number, which is approximately 6.022 × 10²³, is the number of molecules or atoms in one mole of a substance.

The redefinition of the mole in 2019 means that the mass of one mole of carbon-12 is no longer exactly 12 grams. Avogadro's number is derived from the molar mass constant (Mu) and the atomic mass constant (mu). The molar mass constant is currently defined as 1.66053906660(50)×10⁻²⁷ kg, and the atomic mass constant is currently defined as 0.99999999965(30)×10⁻³ kg⋅mol⁻¹.

In summary, a mole is a fundamental unit in chemistry that represents a specific amount of a substance. Avogadro's number, which is approximately 6.022 × 10²³, is the number of molecules or atoms in one mole. The redefinition of the mole in 2019 means that the mass of one mole of carbon-12 is no longer exactly 12 grams.