Question

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

Answer 1

Answer:

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

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 $M_{Si-28} = 27.976\,a.m.u.$, $M_{Si-29} = 28.976\,a.m.u.$, $M_{Si-30} = 29.974\,a.m.u.$, $r_{1} = \frac{92.22}{100}$, $r_{2} = \frac{4.68}{100}$ and $r_{3} = \frac{3.09}{100}$, then the estimated atomic mass of silicon is:

$M_{Si, est} = r_{1}\cdot M_{Si-28} + r_{2} \cdot M_{Si-29} + r_{3}\cdot M_{Si-30}$

$M_{Si,est} = \left(\frac{92.22}{100} \right)\cdot (27.976\,a.m.u.) + \left(\frac{4.68}{100} \right)\cdot (28.976\,a.m.u.) + \left(\frac{3.09}{100} \right)\cdot (29.974\,a.m.u.)$

$M_{Si, est} = 28.082\,a.m.u.$

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