Ion hydration controls self-diffusion in multicomponent aqueous electrolyte solutions of NaNO2-NaOH-H2O

•Water and Na+ diffusion was correlated to the water activity.•Water activity is equated to the “unbound water” in Zavitsas electrolyte model.•Diffusion rates are thus faster in water not strongly held by electrolytes.•Diffusion rates were correlated to nitrite Raman peak widths.•Raman peak widths are expected to be related to molecular rotation.