Question

How do you calculate 1 amu in grams using C-12 atoms?

Answer 1

Hint: The answer here is based on the fact which includes the calculation of atomic mass unit in terms of grams also takes into account the Avogadro constant value to convert it into grams.

Complete step by step answer:
- In the classes of chemistry, we have come across the basic concept of chemistry which tells us about the atoms, their atomic number and also their respective masses and according to which they have been placed in the periodic table.
Let us now see what does the atomic mass unit mean and how can it be converted into grams.
- Atomic mass unit is defined as one – twelfth the mass of an unbound neutral atom of carbon – 12 atoms in its nuclear and electronic ground state and which is at rest.
-Now, we know that the mass of one carbon atom which is having the atomic number 12 is = 12 u or amu.
According to the Avogadro law, one mole of any substance has the Avogadro number of molecules that is $6.023\times {{10}^{23}}$ atoms.
- Now, $6.023\times {{10}^{23}}$ carbon atoms will have mass of 12 g
Therefore, by the cross multiplication method, the mass in grams for 1 unit of the substance will be,
1u = $1u\times \dfrac{1C-atom}{12u}\times \dfrac{12g}{6.023\times {{10}^{23}}C-atoms}$
= $1.661\times {{10}^{-24}}g$
Therefore, the correct answer is 1 amu of carbon – 12 atoms will have $1.661\times {{10}^{-24}}g$

Note: Note that the atomic mass unit of an element is also denoted in terms of Dalton units which has the symbol ‘D’ or sometimes as ‘Da’ which is also defined as one – twelfth the mass of carbon – 12 atom which has the value of 1u = $1.66\times {{10}^{-27}}kg$