Apowder contains feso4⋅7h2o (molar mass=278.01 g/mol), among other components. a 2.955 g sample of the powder was dissolved in hno3 and heated to convert all iron to fe3+. the addition of nh3 precipitated fe2o3⋅xh2o, which was subsequently ignited to produce 0.201 g fe2o3. what was the mass of feso4⋅7h2o in the 2.955 g sample?

Explanation:

According to the reaction, 2 moles of =

Molar mass of is 159.69 g/mol and mass is given as 0.201 g.

Therefore, calculate the number of moles of as follows.

            No. of moles =

                                  =

                                  = mol

Hence, moles of = 2 × moles of                            

Therefore, moles of  = mol

                                                       = 0.0025 mol

Now, calculate the mass of as follows.

            No. of moles =

              mass = no. of moles × molar mass of

                        =

                        = 0.695 g

Thus, we can conclude that 0.695 g is the mass of in 2.955 g of the given sample.