Question

The formula of dichromate, sulfide, and ferricyanide ions respectively are______

Answer 1

Ions: It is defined as an atom or molecule which is formed by the gain or loss of electrons.

The formula for dichromate ion is given as ${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}$.

• The dichromate ion has 2 Chromium(Cr) and one Chromium has a charge equal to +6.
• So, two Chromate ions will have 2 X +6 = +12
• The Dichromate ion has 7 Oxygen(O), and one Oxygen has a charge equal to -2
• So, seven oxygen ions will have 7 X -2 = -14
• Therefore, the overall formula of chromate ion will have a charge equal to -2, and the formula becomes ${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}$.

The formula for sulfide ion is given as ${\mathrm{S}}^{2-}$ .

• Sulfide ions forms when sulfur atom gains 2 electrons to complete its octet.
• Therefore, the overall formula of sulfide ions as ${\mathrm{S}}^{2-}$.

And the formula for ferricyanide ion is given as $[\mathrm{Fe}{\left(\mathrm{CN}\right)}_6{]}^{3-}$.

• Ferri means Iron(Fe) having a charge equal to 3.
• The ferricyanide ion has one Iron(Fe) atom having a charge equal to +3.
• The ferricyanide ion has six cyanide(CN) ions each having a charge equal to -1.
• So, six cyanide(CN) ion will have 6 X -1 = -6.
• Therefore, the overall formula of ferricyanide ion will have a charge equal to -3, and the formula becomes $[\mathrm{Fe}{\left(\mathrm{CN}\right)}_6{]}^{3-}$.

Hence, the formula of dichromate, sulfide, and ferricyanide ions respectively are ${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}$, ${\mathrm{S}}^{2-}$, $[\mathrm{Fe}{\left(\mathrm{CN}\right)}_6{]}^{3-}$.