Answer to Question #269764 in General Chemistry for Faith

Question

How can 3Mg + 2Ni(NO3)3 --> 2 Ni +3 Mg(NO3)2 be written in formula with Roman numerals?

Answer 1

Roman numerals are used to specify the oxidation state of a metal in its compound, but only if this metal is able to form compounds with different oxidation states. For example, the name of Ni(NO₃)₃ is Nickel(III) nitrate, where roman numeral "III" corresponds to the oxidation state +3 of nickel (nickel also forms compounds with oxidation state +2, which are more common). This rule, however, does not apply to Mg(NO₃)₂ as +2 is the only possible oxidation state of magnesium in its compounds, hence no roman numeral is required to indicate this. In formulas and chemical equations, roman numerals are never used, so the overall question does not sound correctly.