Rubidium has two naturally occurring isotopes: 85Rb and 87Rb. The natural abundance of 85Rb is 72.165% and it has an isotopic mass of 84.9118 u.
Calculate the isotopic mass of 87Rb
so the answer will be 85.06912663u?
abundance Rb 85 = 72.165%. Then Rb 87 = 100% - 72.165% = 27.835%
(72.165*84.9118) + (X*27.835) = atomic mass Rb.
Look up the atomic mass of Rb on the periodic table (it should have been given in the problem---perhaps you just didn't type it in). Anyway, look up the atomic mass of Rb from the periodic table and solve for X in the equation i wrote above. Post your work if you get stuck.
To calculate the isotopic mass of 87Rb, we can use the fact that the sum of the atomic masses of the naturally occurring isotopes equals the atomic mass of the element.
Let's denote the isotopic mass of 87Rb as x.
Since the natural abundance of 85Rb is 72.165%, the natural abundance of 87Rb would be (100% - 72.165%) = 27.835%.
Now we can set up the equation:
(72.165/100) * 84.9118 u + (27.835/100) * x = atomic mass of rubidium
Simplifying the equation:
(0.72165) * 84.9118 + (0.27835) * x = atomic mass of rubidium
61.2608 + (0.27835) * x = atomic mass of rubidium
Lastly, we can solve for x by isolating it on one side of the equation:
(0.27835) * x = atomic mass of rubidium - 61.2608
x = (atomic mass of rubidium - 61.2608) / 0.27835
Since we don't have the exact atomic mass of rubidium, we cannot provide the exact value of the isotopic mass of 87Rb.
To calculate the isotopic mass of 87Rb, we can use the concept of weighted averages.
Let's assume the isotopic mass of 87Rb is x u.
Given that the natural abundance of 85Rb is 72.165%, we can calculate the natural abundance of 87Rb by subtracting this value from 100%: 100% - 72.165% = 27.835%.
Now, we can set up the equation:
(72.165/100) * 84.9118 + (27.835/100) * x = average atomic mass of Rubidium
The average atomic mass of Rubidium is approximately 85.4678 u.
Plugging in the values, we get:
(72.165/100) * 84.9118 + (27.835/100) * x = 85.4678
Simplifying the equation, we have:
61.35553547 + (27.835/100) * x = 85.4678
Rearranging the equation to solve for x:
(27.835/100) * x = 85.4678 - 61.35553547
(27.835/100) * x = 24.11226453
Dividing both sides of the equation by (27.835/100):
x = 24.11226453 / (27.835/100)
x = 24.11226453 * (100/27.835)
x ≈ 86.9238 u
Therefore, the isotopic mass of 87Rb is approximately 86.9238 u.