124. Solving a chemistry problem

13. Determine the silver content in copper castings according to the measured blackening of analytical lines from the spectra of samples and standard samples:
Sample CAg,% SAg,%SCu ∆S
standard 1 0.18 0.41 0.64
Standard 2 0.23 0.45 0.66
Standard 3 0.40 0.55 0.55
Sample? 0.18
The calibration graph is plotted in the coordinates ΔS from lg(СAg). We need to prepare the data for plotting by calculating the differences ΔS = SCu - SAg and the logarithm of the silver concentration.
СAg, % log(СAg) SAg SCu ΔS
0.18 -0.745 0.41 0.64 0.23
0.23 -0.638 0.45 0.66 0.21
0.40 -0.398 0.55 0.65 0.10