How would you write the chemical formula for Mercury(I) nitrate.

i have Hg(NO3)2 since the charge of nitrate is -2 and Mercury's is 1.

However, upon checking online i found that the correct formula is Hg2(No3)2. I don't understand where the subscript 2 of Hg originated from'
Thanks

3 answers

You are absolutely correct on one count and not quite right on the second. Hg occurs both as Hg(I) and Hg(II) but nitrate is -1, not -2 We NORMALLY use the smallest set of subscripts but in the case of Hg(I) compounds, most of them are dimeric. Hg2Cl2, Hg2(NO3)2, etc. Note that there also is a mercury(II) nitrate; i.e., Hg(NO3)2. Therefore, although the empirical formula for mercury(I) nitrate is HgNO3, the molecular formula is Hg2(NO3)2 anf I was always encouraged to write the molecular formula instead of the empirical formula.
YOUR RIGHT,the charge of nitrate is -1, my mistake. But I still don't understand how to figure out the formula for Mercury(I) nitrate. Given that the charge for mercury in this case is -1 and nitrate is -1 also then where do the subscripts "2" come from, [given that the correct formula is Hg2(NO3)2]
my question
1.Does it mean my mercurous nitrate has expired if the color and appearance changes from white or colorless crystals to yellowish watery caked.
2
the product above when prepared and titrated against a solution of iron thiocynate forms a precipitate which at it original state will turn the bloody color of thye iron thiocynate to colourles. why it is it so