Một hchc A có công thức CnH2nO2 tác dụng với 90,91ml dd NaOH 8% (d=1,1 g/mol) ( lượng NaOH dùng vừa đủ ) theo tỉ lệ mol 1:1 cho 2 sản phẩm có tổng khối lượng là 25,6(g) a) tính khối lượng của A

b) xác định CTPT của A

List four observations that indicate that a chemical reaction may be taking place

Salicylic acid is a very important acid. it is used to synthesize the aspirin by treating with acetic anhydride. a 0.2015-g sample of salicylic acid was dissolved in a 100.00-ml volumetric flask, and the solution was diluted to the mark. a 10-ml aliquot of this solution was titrated with standard naoh (0.01130 + 0.2% n) to a phenolphthalein faint pink color end point at 19.81 ml. (a) (calculate the normality of the salicylic acid solution used in the titration. (b) assuming the salicylic acid is pure, what is the equivalent weight of the salicylic acid? practice problems for the final exam (continued) (c) (calculate the inherent error in the determination of the equivalent weight you calculated in part (b). use the following absolute errors in the equipment /glassware when calculating the inherent error. 5.00-ml pipet: + 0.02 ml 100-ml volumetric flask: + 0.08 ml analytical balance: + 0.2 mg 25-ml buret: + 0.03 ml

How many protons, electrons, and neutrons are in each of the following isotopes? a. zirconium-90 b. palladium-108 c. bromine-81 d. antimony-123