What information is required to calculate the average atomic mass of an element

The average atomic mass of an element is the sum of the masses of its isotopes, each multiplied by its natural abundance

Explanation:

To determine the average atomic mass, we require abundance of every isotope in the nature.

Average atomic mass is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.

when [oh-] is 10-5  m, and [h3o+] is 10-9  m, the poh is 5 and ph is 9. again in both cases the sum of ph and poh is 14. however, the hydrogen ion concentration is not always going to be equal to exactly 1 x 10 raised to a negative number. for example, we skipped over the value of 2.0 x 10-7.