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In: Chemistry

analysis of mercury (200.59 g/mol) in the sample of mercuric ointment described here. A 4.026 g...

analysis of mercury (200.59 g/mol) in the sample of mercuric ointment described here. A 4.026 g sample of a mercuric ointment is digested in nitric acid. After dilution, the Hg2+ is titrated with 23.05 mL of a 0.1124 M solution of NH4SCN. The titration involves the formation of a stable, neutral complex: Hg2+ (aq) + 2 SCN- (aq) = Hg(SCN)2 (aq)

How many mmoles of mercury are in the sample?

How many mg's of mercury are in the sample?

What is the percent mercury (w/w) in the ointment?

Expert Solution

Hg2+ (aq) + 2 SCN- (aq) ----------------> Hg(SCN)2 (aq)

number of mmoles of SCN- = 23.05 x 0.1124

= 2.591

number of mmoles of Hg+2 = 2.591 / 2

= 1.296

number of mmoles of Hg+2 = 1.296

mass of Hg+2 = mmoles x molar mass of Hg

= 1.296 x 200.59

mass of Hg+2 = 259.96 mg

mass of sample = 4.026 g

percent mercury (w/w) = (mass of Hg+2 / mass of sample ) x 100

= (259.96 x 10^-3 / 4.026 ) x 100

= 6.46 %

percent mercury (w/w) = 6.46 %

molar mass =

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