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Can someone enlighten me with this method - (Aug/10/2018 )

Hello everyone,


I am having trouble understanding this one, well maybe because I am still a student. This is the method:


The samples will be filtered through Whatman no. 2 filter paper to remove coal particles from the liquid medium. The filtrated solids will be washed with 5 ml of 0.1 N HCL to extract adsorbed sulfate and into the filtrate (Silverman et al., 1963). The filtrate will be analyzed for sulfate.

Sulfate concentration will be measured turbidimetrically (Karr, 1978). Two milliliters of 10% BaCl solution will be added to 2 ml of diluted liquid filtrate, and the turbidity of the final mixture will be measured by using a spectrophotometer at 450 nm.

Total sulfur content of coal samples will be determined by using Eschka method. (Karr, 1978)


How can the spectrophotometer show the percentage of sulfate concentration? 

Anyways hoping for your kind consideration and answers.


-Daniel Alexis-

barium sulfate is insoluble and will form by substitution of the chloride. this will cause turbidity in the solution, the degree of which will be determined by reduction of transmitted light at 450nm. this should be compared with a standard curve to determine %.