# Any differences in metal ion emission spectra?

If I measure the emission spectra of potassium using the following solutions

1) $0.1~\mathrm{M}$ of $\ce{KNO3}$

2) $0.1~\mathrm{M}$ of $\ce{K2SO4}$

will I see any significant differences?

I think there will be no significant differences because the spectrum does not depend on whether in 1) I am using $\ce{K}$ while in 2) I am using $\ce{K2}$ (the emission spectrum should be independent). Am I right?

• You have neither $\ce{K}$ nor $\ce{K2}$. In both cases, you have $\ce{K+}$ ions, and they are the same. – Zhe Nov 24 '16 at 4:13
• They look the same but intensities would be different – user1420303 Nov 24 '16 at 11:19

$0.1~\mathrm{M}$ $\ce{KNO3}$ dissociates to give $0.1~\mathrm{M}$ $\ce{K+}$ ions.
$0.1~\mathrm{M}$ $\ce{K2SO4}$ dissociates to give $2 \times 0.1~\mathrm{M}$ $\ce{K+}$ ions.
Hence, in terms of emission intensity, $\ce{K2SO4}$ should give twice the signal if other parameters are same and if the detection response is linear.