Calculating the Mass of a Negative Ion with a Specific Charge

[ManchesterDan]

Calculate the mass of an ion that has a specific charge of 1.20x10^7 C kg^-1 and a negative charge of 3.2x10^-19 C.

Textbook answer: 2.67x10^-26 kg.

Question: if the ion has a negative charge of 3.2x10^-19, isn't that -3.2x10^-19?! In which case the answer would be -2.67x10^-26 kg?! Is the use of the word negative in this question a bit misleading?

 

[Dadface]

Hello Dan.West Ham supporter here(don't take the mickey).You make an interesting point.Specific charge is a ratio and I don't recall having seen it given either a positive or negative label.Thinking about it,it might seem to be more instructive to do so.

 

[ManchesterDan]

Hi Dadface, it isn't actually the specific charge I'm concerned about, its the charge of the ion. Is 'a negative charge of 3.2x10^-19 C' the same as -3.2x10^-19 C?! In which case the answer would be -2.67x10^-26 kg?! Is the use of the word negative in this question just a bit misleading?

Thanks very much!

P.s. Just watching the Bolton game myself!

 

[Dadface]

Yes it is the same and it is twice the charge of the electron.From its charge and mass it looks like it's an oxygen ion.