Lab 6 PostLab - University of Washington CHEM 241

Chem 241 Lab 6 Postlab Estella Rachana Khieu TOTAL POINTS 45.5 / 49 QUESTION 1 1 Page 1 Q1/2 4 / 4 ✓ - 0 pts Correct - 2 pts Q1 - wrong ID - 1 pts Q2 mass missing - 0.5 pts Q2 yield < 20% (theoretical y ...

Chem 241 Lab 6 Postlab Estella Rachana Khieu TOTAL POINTS 45.5 / 49 QUESTION 1 1 Page 1 Q1/2 4 / 4 ✓ - 0 pts Correct - 2 pts Q1 - wrong ID - 1 pts Q2 mass missing - 0.5 pts Q2 yield < 20% (theoretical yield 3-3.75 grams depending on which benzoic acid) - 1 pts Q2 mp missing - 0.5 pts Q2 mp off by more than 10C benzoic acid: 122C 2-methylbenzoic acid: 102C 4-methylbenzoic acid: 179C 2,5-dimethylbenzoic acid: 132C - 4 pts All blank / wrong - 9.8 pts Late (applies to whole lab) - 1 pts Q2 % yield calculation incorrect QUESTION 2 2 Page 1 Q3 4 / 4 ✓ - 0 pts Correct - 2 pts carboxylate intermediate not present - 1 pts curved arrows wrong in 1st step - carbanion attack CO2 (can treat Grignard reagent as phenyl carbanion) - 1 pts curved arrows wrong in 2nd step - protonation (can use any general acid) - 1 pts first step wrong QUESTION 3 3 Page 1 Q5 (Q4 on separate page) 2 / 2 ✓ - 0 pts Data agrees - 0 pts Data disagrees and they explain which is more trustworthy - 2 pts Data disagrees and they don't explain which is more trustworthy - 2 pts Q5 missing QUESTION 4 4 WebMO page 1 Q1 - regrade requests must include your NetID 2 / 2 ✓ - 0 pts Correct - 0.5 pts bromobenzene ipso C off by more than 0.1 from -0.11 - 0.5 pts bromobenzene Br off by more than 0.1 from +0.05 - 0.5 pts Grignard ipso C off by more than 0.1 from -0.64 - 0.5 pts Grignard Br off by more than 0.1 from -0.75 - 2 pts Blank / wrong QUESTION 5 5 WebMO page 1 Q2 - regrade requests must include your NetID 1.5 / 2 - 0 pts Correct - 0.5 pts C-Br bond order off by more than 0.2 from 1.0 ✓ - 0.5 pts C-C bond order off by more than 0.2 from 1.4 - 0.5 pts C-Mg bond order off by more than 0.2 from 0.4 - 0.5 pts Mg-Br bond order off by more than 0.2 from 0.4 - 2 pts wrong / blank QUESTION 6 6 WebMO page 1 Q3/4 - regrade requests must include your NetID 1 / 2 - 0 pts Correct - 1 pts Q3 they don't say "para" or "ortho / para" ✓ - 1 pts Q4 they don't say "ipso" QUESTION 7 7 WebMO page 2 Q5/6 - regrade requests must include your NetID 4 / 4 ✓ - 0 pts Correct - 1 pts Q5 - they don't say partway between single and double bonds - 1 pts Q5 - they don't explain this because the bond order is between 1 and 2 - 1 pts Q6 - they don't say partway between covalent and ionic - 1 pts Q6 - they don't explain this because the bond order is between 0 and 1 - 2 pts Blank / wrong QUESTION 8 8 WebMO page 2 Q7 - regrade requests must include your NetID 2 / 2 ✓ - 0 pts Correct - 1 pts They don't say this is consistent with bromobenzene as an EAS ortho/para director - 1 pts They don't say this is consistent with phenyl magnesium bromide doing Grignard addition reactions QUESTION 9 9 NMR - 1 page only 2 / 2 ✓ - 0 pts Correct - 1 pts Solvent / TMS peaks not labelled if they are present - 1 pts benzoic acid peaks not labelled, including correct integration (benzene peaks can be lumped together) QUESTION 10 Notebook 20 pts 10.1 Goal / Procedure 4 / 4 ✓ - 0 pts Correct - 1 pts Goals missing - 0.5 pts Goals partial or vague - 3 pts Procedure missing - 1.5 pts Procedure partial / incomplete - 0 pts Procedure written verbatim from manual - no point deduction, but letting students know that it wasn't necessary - 4 pts Missing 10.2 Safety / Reaction Table 5 / 5 ✓ - 0 pts Correct - 2 pts Safety missing - 1 pts Safety partial - missing for some reactants / products / solvents - 3 pts Reaction table missing - 1.5 pts Reaction table partial - missing data for some compounds - amounts, yields, key physical properties - 1.5 pts Reaction table partial - some compounds missing entirely - 5 pts Missing 10.3 Data / Goal / Conclusion 3 / 3 ✓ - 0 pts Correct - 1 pts No quantitative data e.g. melting point, yield - 1 pts No qualitative data e.g. colors, crystal structures, physical changes - 1 pts Conclusion missing or incomplete - 3 pts Missing 10.4 Purification flowchart 8 / 8 ✓ - 0 pts Correct - 2 pts They don't correctly scale based on stoichiometry - 2 pts They don't choose acid-base extractions - 2 pts They include extraneous steps, like extracting with HCl when there is no amine - 2 pts They don't include a neutralization to get a neutral benzoic acid to precipitate - 8 pts Blank / wrong QUESTION 11 11 Safety - don't tag any pages 3 / 5 - 0 pts Correct ✓ - 2 pts Safety deduction - student exhibited unsafe behavior like horsing around or bringing open vial of volatile solvent up to TA - 2 pts Safety deduction - student did not know key procedural information like where to dispose of material, or which layer contains which solvent - 2 pts Safety deduction - student did not clean their fume hood or communal space - 2 pts Safety deduction - student wore gloves outside lab or brought contam