Question

Please show the work. Thank you

Formula of a Hydrate

Data:

Mass of the crucible and cover                                              51.729g

Mass of crucible, cover and sample                                       52.388g

Mass of crucible, cover and salt after first heating               52.258g

Mass of crucible, cover and salt after second heating          52.254g

Calculations:

Chemical formula of anhydrous salt (given)                          CaSO4

Mass of hydrate (sample)                                                      0.659g

Mass of anhydrous salt                                                          ______ ?

Mass of water liberated                                                         ______ ?

Percentage H2O in the hydrate                                              ______ ?

Moles of anhydrous salt in the hydrate                                 ______ ?

Moles of water in 100g of hydrate                                        ______ ?

Moles of water in 100g of hydrate                                        ______ ?

Moles of water per mole of anhydrous salt                          ______ ?

Average Moles of water per mole of anhydrous salt                        ______ ?

Formula of the Hydrate                                                          ______ ?

Answer 1

Mass of anhydrous salt =  52.388 - 52.254 = 0.134 gm

Mass of water liberated = 0.134 gm

Moles of water = 0.134 /18 = 0.007444 Moles

Moles of CaSO4 is present = 0.659 /136.1406 = 0.00484 Moles

(Molar mass of CaSO4 is 136.1406 g/mol)

Percentage H2O in the hydrate = 0.134 x 100 / 0.659 = 20.33 %  

Moles of water in 100g of hydrate =  0.007444 x 100 / 0.659 = 1.129 Moles

Moles of water per mole of anhydrous salt =  0.007444 /  0.00484 = 1.5

Average Moles of water per mole of anhydrous salt = 1.5

Formula of the Hydrate = (CuSO₄)₂. 3H₂O