(1)由溶解度的性质得:S/(S+100) = w,所以溶解度S = 100w/(1 - w)(2)n(NaOH) = m/40 mol所以溶质的物质的量浓度c = (m/40)/v mol/L(3)n(NaOH) = m/40 molm(溶液) = m/wV(溶液) = (m/w)/d ml = m/1000dw L所以溶质的物质的量浓度c = (m/40)/(m/1000dw) = 25dw mol/L