Magnesium oxide is a compound of magnesium and oxygen. How do you know that it is a completely different substance from each of the two elements it is made up of?

1 Answer
anor277
Jul 27, 2017

By interrogating its melting point, boiling point, composition, appearance, chemical reactivity..........

Explanation:

Magnesium is a silvery metal with a metal point of #650# #""^@C#, and an atomic mass of #24.32*g*mol^-1#. Oxygen is a colourless, room termperature gas with a boiling point of #-182.3# #""^@C#, and a molecular mass of #32.00*g*mol^-1#.

#MgO# is a white, hygroscopic solid with a metal point of #2825# #""^@C#, and a formula mass of #40.31*g*mol^-1#. The difference in physical AND chemical properties dictate a difference in chemical composition and formula.

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