Determination of Mn in Steel via Spectrophotometry new PDF

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Determination of Mn in Steel via Spectrophotometry Olivia pizzella Oct 4th 2020 Dr.Nirode

Mass of standard sample = 0.5174g, mass of unknown standard sample = 0.4198g wavelength : N/A (scan not in email) Calibration plot

The standard is 0.83% Mn by mass Absorbance & concentrations for Mn in the five standard samples Concentration

Absorbance 0

0.476

0.002257

0.124

0.003695

0.203

0.005461

0.3

0.007227

0.397

Absorbance and calculator Mn concentration in unknown samples ( unknown N/A was not sent in email) Unknown is 97.29% Absorbance & concentrations for Mn in the five standard samples unknown concentration

absorbance 0.0091556

0.382

0.0020753 0.0028217 0.0046422 0.0055889

0.114 0.155 0.255 0.307

Summary

Unknown #

N/A not sent in email

Average

0.00485674

Standard std

0.002487572

95% conf. Interval

0.004857 ±0.00218

Calculations: 1. Dilutions of the standard sample (and of unknown if different) ■ m1= 0.1910 2. Sample calculation for Mn concentration in diluted standard (used to create plot) ■ x=0.000000019047619 3. Sample calculation for Mn concentration (as %) in unknown sample ■ 0.0206%

Thought Questions: 1.Why is phosphoric acid added to the Mn steel solution? Ferric ions are produced from the iron that can be major interferences in the determination of the magnanes, to prevent this we add phosphate 2.Chromium is also found in steel at trace levels. If present, the chromium would have been oxidized to chromate or dichromate. Both chromate and dichromate absorb light

in the visible region and could thus have interfered with your Mn measurements. How would standard addition calibration have corrected for this interference? -

the standard sample minimizes the spectral interferences in the analysis...