Fifty food supplement tablets with a total mass of 66.393 g were crushed into powder to analyse the content of FeSO4·7H2O. 2.988 g of the powder were dissolved in HNO3 and heated to convert all the iron to Fe3+. Addition of aqueous NH3 caused quantitative precipitation of Fe2O3·xH2O, which was ignited to give 0.0640 g of Fe2O3. Determine the average weight of FeSO4·7H2O in each tablet.

Phosphate buffers are important in regulating the pH of intracellular fluids. If the concentration ratio of H2PO4/HPO42 in a sample of intracellular fluid is 1.1: 1, what is the pH of this sample of intracellular fluid? H2PO4(aq)HPO42(aq)+H+(aq)Ka=6.2108

A mixture of xenon and ?uorine was heated. A sample of the white solid that formed reacted with hydrogen to yield 81 ml of xenon (at STP) and hydrogen ?uoride, which was collected in waiter, giving a solution of hydro?uoric acid. The hydro?uoric acid solution was titrated, and 68.43 mL of 0.3172 M sodium hydroxide was required to reach the equivalence point. Determine the empirical formula for the white solid and write balanced Chemical equations for the reactions involving xenon.

Twenty tablets of an iron food supplement whose total mass was 22.131 g were crushed and perfectly mixed. Then 2.998g of the powder was dissolved in HNO3 and the solution was heated to convert all the iron to Fe+3. By addition of NH3 it was quantitatively precipitated as Fe(OH)3•H20 which was calcined to form 0.264g of Fe203. Calculate the Fe content in each tablet.