Question- A 4.030g sample of solid containing only NaNO2 and NaNO3 was dissolved in 500.0 mL of water (no volume change). A 25.00 mL sample of this solution was withdrawn and treated with 50.00 ml of 0.1186 M Ce^+4 in acid solution, and after a few minuted the excess Ce^+4 was black-titrated, requiring 31.13 mL of 0.04289 M Fe^+2 solution.
Calculate the weight percent of NaNO3 in the solid. (Assume all the reactions go to completion and NaNO3 doesnt react)
I have no idea how to do this! Thank you for your help!