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题目:(2001年全国初中化学竞赛题)将由某化合物R和Na2SO4组成的固体混合物放人足量的水中,充分搅拌,过滤得到11.65g白色沉淀,经实验测知该白色沉淀不溶于稀硝酸,滤液呈碱性。用146g 5%的盐酸来中和滤液后所得溶液恰好呈中性。求混合物中R的质量。
Title: (2001 national junior high school chemistry competition title) A solid mixture consisting of a certain compound R and Na2SO4 is put into a sufficient amount of water, stirred well and filtered to obtain 11.65 g of a white precipitate. The white precipitate is insoluble in dilute nitric acid. The filtrate is alkaline. The solution obtained after neutralizing the filtrate with 146 g of 5% hydrochloric acid was exactly neutral. Find the mass of R in the mixture.