Strontium consists of four isotopes with masses of 84 (abundance 0.50%), 86 (abundance of 9.9%), 87 (abundance of 7.0%), and 88 (abundance of 82.6%). calculate the atomic mass of strontium.

Answer :

87.62 u

Explanation:

The atomic mass of Sr is the weighted average of the atomic masses of its isotopes.

We multiply the atomic mass of each isotope by a number representing its relative importance (i.e., its percent of the total).

Set up a table for easy calculation

0.0050 × 83.91 u =  0.420 u

0.099   × 85.91 u =  8.505 u

0.070   × 86.91 u =  6.084 u

0.826   × 87.91 u = 72.61   u

               TOTAL = 87.62  u

the answer for sodium is 0.186

the answer for rubidium is 0.251

answers: to make sure that all of the broken pieces of tablet were added to the water, to allow for fair comparison of all three trials, with different particle sizes to avoid experimental error