Question

ASAP:

The estimated atomic mass of silicon could be Choose... amu because the Choose.. abundant isotope is Choose...​

Answer 1

The estimated atomic of silicon is 28.082 a.m.u.

Step-by-step explanation:

The estimated atomic mass of silicon (
`M_(Si, est)`), in a.m.u., is equal to the weighted average of atomic masses of silicon available in nature and in terms of their abundances:

`M_(Si, est) = r_(1)\cdot M_(Si-28) + r_(2) \cdot M_(Si-29) + r_(3)\cdot M_(Si-30)` (1)

Where:

`r_(1)`,
`r_(2)`,
`r_(3)` - Relative abundance of each isotope, no unit.

`M_(Si-28)`,
`M_(Si-29)`,
`M_(Si-30)` - Atomic mass of each isotope, in a.m.u.

If we know that
`M_(Si-28) = 27.976\,a.m.u.`,
`M_(Si-29) = 28.976\,a.m.u.`,
`M_(Si-30) = 29.974\,a.m.u.`,
`r_(1) = (92.22)/(100)`,
`r_(2) = (4.68)/(100)` and
`r_(3) = (3.09)/(100)`, then the estimated atomic mass of silicon is:

`M_(Si, est) = r_(1)\cdot M_(Si-28) + r_(2) \cdot M_(Si-29) + r_(3)\cdot M_(Si-30)`

`M_(Si,est) = \left((92.22)/(100) \right)\cdot (27.976\,a.m.u.) + \left((4.68)/(100) \right)\cdot (28.976\,a.m.u.) + \left((3.09)/(100) \right)\cdot (29.974\,a.m.u.)`

`M_(Si, est) = 28.082\,a.m.u.`

The estimated atomic of silicon is 28.082 a.m.u.