Question

The minera pyrrhotite has the formula Fe (1-x)S. calculate the value of X for each of the following analyses.

Elmts 1 2 3 Fe 56.49 61.49 56.74 Co 1.50 0.49 Ni 4.30 0.39 1.10 S 36.71 37.18 41.67 Insol. res 0.33 0.46 99.33 99.52 100.00 Ignore the insoluble residue; include atomic Ni and Co along Fe (Sum Them)

Answer 1

solution

:

Element 1 2 3

Fe 56.49 61.49 56.74

Co 1.50 0 .49

Ni 4.30 0.39 1.10

S 36.71 37.18 41.67

insol resid. 0.33 0.46

=99.33 =99.52 =100.00

1) Here the moles of Fe = Mass / atomic weight =   56.49 / 55.8 = 1.01

Moles of Ni = Mass / atomic weight   = 4.30 / 58.69 = 0.073

Moles of Co = Mass / atomic weight   =1.5 / 58.9 = 0.025

Moles of S = Mass / atomic weight   = 36.71/ 32 = 1.147

total moles of Fe+ Ni + Co = 1.108

so if S = 1.147 Fe = 1.108

so if S = 1 Fe = 0.965

So 1-x = 0.965

x = 0.035

2)

1) Here the moles of Fe = Mass / atomic weight =    61.49/ 55.8 = 1.101

Moles of Ni = Mass / atomic weight   =   0.39/ 58.69 = 0.0066

Moles of Co = Mass / atomic weight   =   

Moles of S = Mass / atomic weight   = 37.18/ 32 = 1.161

total moles of Fe+ Ni + Co = 1.101 + 0.0066 = 1.1076

so if S = 1.161 Fe = 1.1076

so if S = 1 Fe = 0.954

So 1-x = 0.954

x = 0.046

3)

Here the moles of Fe = Mass / atomic weight = 56.74 / 55.8 = 1.106

Moles of Ni = Mass / atomic weight   = 1.1 / 58.69 = 0.0187

Moles of Co = Mass / atomic weight   = 0.49 / 58.9 = 0.0083

Moles of S = Mass / atomic weight   = 41.67 / 32 = 1.302

total moles of Fe+ Ni + Co = 1.133

so if S = 1.302 Fe = 1.133

so if S = 1 Fe = 0.870

So 1-x = 0.870

x = 0.13