When 2.246 grams of a calcium chloride hydrate was heated, 0.728 grams of water were
released. determine the formula of the hydrate

CaCl₂. 3H₂O

We are given;

We are required to determine the formula of the hydrate;

First; we determine the mass of the anhydrous salt

Mass of anhydrous Calcium chloride = Mass of hydrate - mass of water

                                                             = 2.246 g - 0.728 g

                                                            = 1.518 g

Second; determine the moles of anhydrous salt and water

Moles = mass ÷ molar mass

Moles of anhydrous salt

Molar mass of CaCl₂ = 110.98 g/mol

Moles of CaCl₂ = 1.518 g ÷ 110.98 g/mol

                         = 0.0137 moles

Moles of water

Molar mass of water = 18.02 g/mol

Moles of water = 0.728 g ÷ 18.02 g/mol

                        = 0.0404 moles

Third; we determine the whole number mole ratio of anhydrous salt to water

CaCl₂  : H₂O

0.0137 moles : 0.0404 moles

0.0137/0.0137  : 0.0404/0.0137

                   1 : 2.95

                   1 : 3

Therefore, the formula of the hydrate is CaCl₂. 3H₂O

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.

i think that the answer is c