90. Solving a chemistry problem

9. The reaction mass after nitration of toluene was analyzed by gas-liquid chromatography using ethylbenzene as an internal standard. Determine the mass fraction of unreacted toluene according to experimental data: a sample of the reaction mass is 12.7500 g, ethylbenzene is added 1.2530 g, the peak area of toluene is 307 mm2, the correction factor for toluene is 1.01, the peak area of ethylbenzene is 352 mm2, the correction factor is 1.02.