In a volumetric determination of an analyte A, the data obtained and their stand

Question

In a volumetric determination of an analyte A, the data obtained and their standard deviations are as follows: Initial buret reading 0.19 mL 0.02 mL Final buret reading 9.06 mL 0.03 mL Sample mass 29.0 mg 0.2mg From the data, find the coefficient of variation ofthe final result for the % A tat is obtained by using the equation that follows and assuming there is no ueaamry m the equivalent mass. %A = titrant volume equivalent mass × 100 %/sample mass coefficient of variation = Submit Answer Try Another Version 6 item attempts remaining

Explanation / Answer

Titrant volume = final burette reading – initial burette reading

but standard deviations given, so just subtract it

as ,= 9.06-0.03 ml =9.03 ml

=0.19 ml -0.02 ml =0.17 ml

then titrant volme = 9.03-0.17 = 8.86 ml

then equivalent mass:- you need to find out from the substance used, simply you can use the following equations, Equivalent mass = Molecular mass/ acidity - (for bases)

Equivalent mass = Molecular mass/ basicity - (for acids)

eg: equivalent mass of HCl = 36.5/1 = 36.5 g

for NaOH = 40/1 = 40 g

for H2SO4 = 98/2 = 49g

sample mass given as 29.0 mg ans standard deviation of 0.2 mg therefore, 29-0.2 = 28.8 mg

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