177. The content of samarium in cerium dioxide was determined by the method of additions. A standard solution of samarium nitrate was prepared by dissolving 0.1158 g of Sm2O3 in nitric acid. The dry residue after evaporation was dissolved in water and diluted to 100 ml (solution A). Then 0.10 ml of solution A was diluted with water to 100 ml (solution B). A portion of CeO2 weighing m (mg) was mixed with sodium sulfate and divided into two equal parts. One of them was injected with 0.5 ml of solution B; the mixture was dried and calcined. The luminescence intensity of the obtained phosphors (peak height, mm) turned out to be:
Task number 177
m, mg 170
hx, mm 40
hx+Δ, mm 60
Calculate the mass fraction (%) of samarium in cerium dioxide.

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