The mineral greenockite is a yellow sulfide of cadmium that is 78.0% cadmium and 22.0% sulfur. determine the empirical formula of greenockite.

CdS

We are given;

We are required to determine the empirical formula of cadmium sulfide

Assuming the mass of the cadmium sulfide is 100 g

Mass of cadmium is 78 g

Mass of sulfur is 22 g

But;

Moles = Mass ÷ Molar mass

Molar mass of Cadmium = 112.411 g/mol

Moles of Cadmium = 78 g ÷ 112.411 g/mol

                               = 0.694 moles

                              = 0.69 moles

Molar mass of sulfur is 32.065 g/mol

Moles of sulfur = 22 g ÷ 32.065 g/mol

                         = 0.686 moles

                       = 0.69 moles

Cadmium : Sulfur

          Cd  :  S

   0.69 moles : 0.69 moles

  0.69/0.69  : 0.69/0.69

                   1 : 1

Therefore, the empirical formula of greenockite is CdS

answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.