3. Another way to calculate the number of waters hydrated to an ionic compound is through it's precent composition. An unknown aluminum sulfate hydrate has the formula Al2(SO4)3 ZH2O. If the entire compound is 8.10% Al by mass, calculate the Z value, or how many water molecules are associated with the aluminum sulfate.

Part a) When FeS3 • 2H2O is heated, it gives off water, SO2 and Fe2O3. Is this a chemical or physical change? When CuSO4 • 5H2O is heated, it gives off water and CuSO4. Is this a chemical or physical change? Which of these changes can be easily reversed? Part b) Is the molar ratio of the products is different from the molar ratio in the hydrate formula, has a chemical or physical change taken place?

Cobalt(II) chloride forms several hydrates with the general formula CoCl2 ·x H2O , where  x  is an integer. If the hydrate is heated, the water can be driven off, leaving pure  CoCl2  behind.   Suppose a sample of a certain hydrate is heated until all the water is removed, and it's found that the mass of the sample decreases by 22.% . Which hydrate is it? That is, what is  x ?

Determine the empirical formula of your acid according to the percent composition ( C: 34.3%, H: 4.76%, O: 61.0%).  Identify your acid as one of the four above by comparing your empirical formula to the molecular formulas given. The four possibilities are:      citric acid, a triprotic acid with the formula C6H10O8 or      tartaric acid, a diprotic acid with the formula C4H6O6 or      ascorbic acid, a monoprotic acid with the formula C6H8O7       fumaric acid, a diprotic acid with the formula C4H4O4

A student performed a similar experiment to the one you performed: They took a crucible and lid, cleaned them, heated them over a flame, and after cooling found their combined mass to be 22.538 g. The student then added a sample of zinc(II) sulfate hydrate (ZnSO4·“n”H2O) to the crucible so the combined mass of the sample, crucible, and lid was 25.896 g. They heated this sample for 10 minutes with the lid ajar, let it cool, and measured the mass of the crucible, sample, and lid to be 25.054 g. a. Based on this experiment, what is the formula for they hydrated zinc(II) sulfate compound? b. The student later looked on the reagent bottle for zinc(II) sulfate hydrate and found the actual formula was ZnSO4·7H2O. If everything had been done correctly, what value should the student have expected for the final mass of their sample, crucible, and lid after heating?

A chemical compound has 53.657% C, 3.081% H, and rest of oxygen. Find the empirical formula of the compound. If vapor density of the compound is 850.6 amu, find its molecular formula. Molecular mass = 2×vapor density of a substance.

If 20.6 grams of an aqueous solution of magnesium nitrate, Mg(NO3)2, contains 2.91 grams of magnesium nitrate, what is the percentage by mass of magnesium nitrate in the solution? % Mg(NO3)2