Question

pls help in this answer... with working....

Answer 1

Hydrated zinc chloride contains 79 . 12 % by weight of zinc chloride . Find the form of the hydrated zinc chloride . [ Zn = 65 , Cl = 35 . 5 , 1 = 1 , 0 = 16 ]

Ans .ZnCl , 2150

Answer 2

Answer:

       ZnCl₂ . 2H₂O

Step by step Explanation:

Here are the steps of finding the formula of the hydrated compound:

Step 1: Let us pick 100g sample of the hydrated zinc and use it to calculate the formula

a) Mass of ZnCl₂ = 79.12 % of 100g

79.12/100 × 100 g = 79.12g

b) Mass of H₂O

% weight of H₂O = 100% - 79.12%

                             = 20.88%

20.88% of 100g of the zinc hydrate

20.88/100 × 100g = 20.88g

Step 2: Find the moles of both the ZnCl₂ and the H₂O

           Moles  = mass / molar mass

        a) Moles of ZnCl₂

           Molar mass of ZnCl₂ = 136.4g/mol

           Moles = 79.12g / 136.4gmol⁻¹

                     = 0.58 moles

        b) Moles of H₂O

            Molar mass = 18g/mol

            Moles = 20.88g/ 18gmol⁻¹

                       = 1.16 moles

Step 3: Find the whole number ratio of the moles of the two compounds by divinding both moles with the moles of the ZnCl₂:

                   ZnCl₂ : H₂O

                     0.58 : 1.16

             0.58/0.58 : 1.16/0.58

                         1   : 2

ZnCl₂  = 1

H₂O = 2

Therefore the formula of the hydrate:

                    ZnCl₂ . 2H₂O