Write down the highest oxide of a chemical element of group 5, the molecular weight of which is 142
| February 8, 2021 | education
Write down the highest oxide of a chemical element of group 5, the molecular weight of which is 142, name the chemical element, make the formula of the oxide and acid.
The general chemical formula of the higher oxide of the element (E) group 5 is E2O5.
Let the relative atomic mass (Ar) of the unknown element be x. Then the relative molecular weight of the oxide (Mr):
Мr (E2O5) = 2х + 5 Ar (O) = 2х + 5 × 16 = 2x + 80 = 142.
x = (142 – 80): 2 = 31.
In the Periodic Table of Chemical Elements, we find that this is phosphorus P.
The formula for phosphorus (V) oxide is P2O5.
The formula of phosphoric acid is H3PO4.
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