Unsatisfactory Borderline Satisfactory Excellent Score Incorrect formulas Incorrect charges or Correct equations with in equation. state labels. proper charges and state Q #1 labels. 2 pts. Eqns. 0 points 1 point 2 points Each section or important Plot of pH vs. -0.5 pt for each region point in the pH vs. volume volume is not or point not correctly plot is properly labeled present. identified. Q #2 with the substance present 4 pts. at that point as directed in pH plot prelab. 0 points 1-2 points 3 points 4 points Clear, correct understanding of which Explanation not or indicators are useful and missing an answer to Q #3 which are not useful for one of the three determining each 3 pts. questions. equivalence point in this reaction and why. 0 points 1 point 2 points 3 points Clear, correct calculations of Molarity (4 of them) No calculations or and determination of No determination of Microsoft Equation average + error. or unclear calculations. not used. -1 pt. for each missed Q #4 molarity calculation and -1 5 pts. M Calc. for incorrect average and error calculation. Eq pts 3-4 points 0 points 1-2 points determined using first and second derivatives of pH. 5 points Table and trend given Table included but no Clear description and valid No table or but explanation of explanation. explanation of behavior of Q #5 explanation given behavior of buffers not buffers. 3 pts. Buffers well explained. 0 points 1 point 3 points 2 points Spectra and explanation Clear, correct description Spectra included but attempted but changes of spectra and valid Q #6 No spectra or little to no description with additional acid not explanation of behavior of explanation given or explanation. well explained. indicators with addition of 3 pts. acid. spectra 0 points 1 point 3 points 2 points Total 20 pts
Unsatisfactory Borderline Satisfactory Excellent Score Q #1 Eqns. Incorrect formulas in equation. 0 points Incorrect charges or state labels. 1 point Correct equations with proper charges and state labels. 2 points 2 pts. Q #2 pH plot Plot of pH vs. volume is not present. 0 points 1-2 points -0.5 pt for each region or point not correctly identified. 3 points Each section or important point in the pH vs. volume plot is properly labeled with the substance present at that point as directed in prelab. 4 points 4 pts. Q #3 0 points 1 point Explanation not or missing an answer to one of the three questions. 2 points Clear, correct understanding of which indicators are useful and which are not useful for determining each equivalence point in this reaction and why. 3 points 3 pts. Q #4 M Calc. No calculations or Microsoft Equation not used. 0 points 1-2 points No determination of or unclear calculations. 3-4 points Clear, correct calculations of Molarity (4 of them) and determination of average + error. -1 pt. for each missed molarity calculation and -1 for incorrect average and error calculation. Eq pts determined using first and second derivatives of pH. 5 points 5 pts. Q #5 Buffers No table or explanation given 0 points Table included but no explanation. 1 point Table and trend given but explanation of behavior of buffers not well explained. 2 points Clear description and valid explanation of behavior of buffers. 3 points 3 pts. Q #6 spectra No spectra or explanation given 0 points Spectra included but little to no description or explanation. 1 point Spectra and explanation attempted but changes with additional acid not well explained. 2 points Clear, correct description of spectra and valid explanation of behavior of indicators with addition of acid. 3 points 3 pts. Total 20 pts