Title: CHE2MOC Pre-lab quizzes

Q: What is the molar concentration (in mol/L) of a 100 mL^ solution containing 20 g of sucrose (molecular formula C_12H_22O_11)?
A: 0.58 (± 0.1)

Q: What rotation angle would you expect to observe for a sucrose solution of concentration 0.2 g/cm3 in a polarimeter tube of 20 centimetres pathlength (specific rotation of sucrose: 66 cm3/dm g)
A: 26.4 (± 2)

Q: Methanol is a classed as dangerous good and hazardous substance. What hazards are associated with it?
- highly flammable
- toxic
- teratogenic
- corrosive
A: highly flammable; toxic

Q: A solution containing 1 mmol/L each of compounds 1 and 2 is analysed by UV/vis spectroscopy at a wavelength of 510 nm.  The absorbances of the individual compounds at 1 mmol/L are A1 and A2 (at 510 nm).  What is the absorbance of the mixture?
- A1 x A2
- A1 + A2
- A1 - A2
- A1 or A2, whichever is greater
A: A1 + A2

Q: The TLC in experiment B5 is run with an eluent containing acetic acid.  The R_f value for aspirin under these conditions is approximately 0.8.  How would the R_f value change if the acid were omitted from the eluent?
- Rf would increase
- Rf would decrease
- Rf would remain unchanged
A: Rf would decrease

Q: In the hydrolysis of sucrose in experiment Ins3, what is the role of the hydrochloric acid?
- it is a pH buffer
- it is a catalyst
- it is a reagent
- it is both reagent and catalyst
A: it is a catalyst