SoWhatDoesItIndicate - Explain how the color changes...

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S O W HAT D OES IT I NDICATE L AB R EPORT I NTRODUCTION : 4 PTS Briefly describe general phenomena of chemical indicator and buffer State chemical equations for two principal equilibria (phosphate buffer and indicator) State purpose (determining concs. of major buffer and indicator species through pH range of interest) E XPERIMENTAL : 2 PTS Reference course website and any additional procedural info R ESULTS : 10 PTS Data table for Part 1 showing pH(s) and observed color(s) of solution(s) Sample calculations corresponding to each major type of Excel spreadsheet calculation Table showing portion-by-portion entries for pH; buffer concs. [HPO 4 2- 2 PO 4 - ]; absorbance readings A 440 560 ; and indicator concs. [HIn] & [In - ] Plot of concentration versus pH, including both HPO 4 2- and H 2 PO 4 - on the same graph D ISCUSSION : 15 PTS General description of experiment strategy, e.g. portionwise addition of HCl and use of pH and appropriate absorbance measurements to assess concentration changes
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Unformatted text preview: Explain how the color changes observed with the eyes are logically supported by the spectrophotometer measurements (refer to data from Part 1 and/or Part 2) Explain qualitatively why gradual acidification is accompanied by concentration trends (gradual increases or decreases) for [HPO 4 2-], [H 2 PO 4-], [HIn] and [In-] State pK a of H 2 PO 4- and explain how conc. vs. pH plot reflects this pK a Explain likely sources of error Explain potential impact of experimental error C ONCLUSIONS : 4 PTS Briefly restate overall experimental goal Briefly restate experimental approach R EFERENCE ( S ): 1 PTS F ORMATTING : 4 PTS ( I . E . FORMATTING DEDUCTIONS CAPPED AT 4 POINTS ) N O T ITLE P AGE , MINUS 1 N OT TYPED , MINUS 3 F IRST-PERSON PRONOUN ( S ) USED , MINUS 1 M ULTIPLE MISSPELLINGS , MINUS 2 N O UNITS , MINUS 1 PER VIOLATION ( RESTRICTED BY 4-POINT FORMATTING CAP )...
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