Question

in the determination of sulphate ion concentration in natural water a turbidimeter was calibrated with a series of standard na2so4 solutions.the following data were obtained in the calibration.mg so4/l,cx 0.00,5.00,10.00,15.00,20.00.turbidimeter reading,r 0.06,1.48,2.28,3.98,4.61.assume that a linear relationship exists between the instrument reading and the concentration.plot the data on a graph paper,calculate the least squares slope and intercept and write the equation of the line,calculate the concentration of sulphate in a sample yielding a turbidimeter reading of 2.84.find the standard deviation and the coefficient of variation

Answer 1

In the deterimination of sulphate we will plot a graph between the concentration of sulphate (mg /L) v/s the trubidimeter reading. It will give straight line.

y= mx + c

Here y = turbidimeter reading

x= concentration of sulphate

m = slope

c= intecept

concentration		Turbidimeter
0		0.06
5		1.48
10		2.28
15		3.98
20		4.61

Equation is y = 0.232x + 0.162

Slope = 0.232

Intecept = 0.162

The concentration of a sulphate with turbidimeter reading of 2.84

2.84 = 0.232 x + 0.162

x = 2.678 / 0.232 = 11.54 mg / L