The element gallium has an atomic mass of 69.7 u and consists of two stable isotopes gallium-69 and gallium-71. the isotope gallium-69 has a mass of 68.9 u and a percent natural abundance of 60.4 %. the isotope gallium-71 has a percent natural abundance of 39.6 %. what is the mass of gallium-71

70.9 u

Explanation:

The average atomic mass (AM) of an element can be calculated using the following expression.

where,

: percent natural abundance of each isotope

: mass of each isotope

Let x = mass of ⁷¹Ga. We get,

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.