Question

Two isotopes of Rubidium occur naturally: Isotopes of Rubidium: Rubidium-85 72.15% , 84.9118 amu: Rubidium-87 27.85%, 86.9092 amu. Calculate the average atomic mass for the two isotopes of Rubidium,

A) 85.25 amu
B) 84.9118 amu
C) 86.9092 amu
D) 84.03 amu

Answer 1

The average atomic mass for the two isotopes of Rubidium is approximately 85.40 amu.

Step-by-step explanation:

The average atomic mass for two isotopes of Rubidium can be calculated by multiplying the mass of each isotope by its abundance, and then summing up these products. In this case, we have Rubidium-85 with an abundance of 72.15% and a mass of 84.9118 amu, and Rubidium-87 with an abundance of 27.85% and a mass of 86.9092 amu.

Using these values:

Average atomic mass = (72.15% * 84.9118 amu) + (27.85% * 86.9092 amu)

= 61.24677 amu + 24.15808 amu

= 85.40485 amu

Therefore, the average atomic mass for the two isotopes of Rubidium is approximately 85.40 amu.