In the orthophosphate of element (II), the mass fraction of this element is 68.44%.

In the orthophosphate of element (II), the mass fraction of this element is 68.44%. Determine which element phosphate is in question.

First, we need to draw up an equation where instead of metal we put the sign E.
By condition, we have a two-valence element, more precisely its orthophosphate.
The formula for this element is: E3 (PO4) 2.
Now you need to make up the proportion:
0.6844 – 0.3156
x – 95
The ratio of ions in the salt is 3: 2 or 1.5: 1
We get:
0.6844 / x = 0.003322
Where: x = 0.6844 / 0.003322 = 206.02
We know that the ratio of ions is 1.5 to 1, so we divide our number by 1.5
E = 206.02 / 1.5 = 137
We look at the periodic table, under a mass of 137 g / mol we have the element Ba.
Salt formula: Ba3 (PO4) 2 or barium orthophosphate.