1. Spectrophotometers measure the amount of light absorbed from an incident ray, so must measure the transmitted light. Fluorimeters measure fluoresced light perpendicular to the incident ray because fluorescence occurs in all directions, and the perpendicular direction is the least affected (swamped) by the transmitted (excitatory) light.
  2. Energy changes:.

    Compound

    ΔE (kJ mol−1)

    β-Carotene

    256

    Lycopene

    249

    Vitamin-A

    369
  3. A = εCl = 6.22 × 103 L mol−1 cm−1 × 50 × 10−6 M × 1 cm = 0.311.
  4. The compound has a broad peak at 3200 (O-H stretch), a sharp peak at 2900 (C-H stretch), a sharp peak at 1400 (C-H deformation), no peak at 1700 (no C=O) and a sharp peak at 1150 (C-O stretch). This is consistent with the compound being an alcohol.

  5. Plastic contains (at the very least), massive amounts of C-H groups, which would overwhelm the signal from the specimen if a cuvette were made from it. A similar argument applies to glass. Sodium chloride is transparent to the infrared spectrum used in IR spectroscopy.
  6. GFP is non-invasive, its fluorescence (particularly in bacteria and cell culture) is readily seen by simply shining light onto the specimen. Furthermore, the GFP gene can be fused to others (e.g. viral coat proteins) to produce fluorescently-marked fusion products (which allows the movement of e.g. viruses within a plant to be easily tracked).
  7. Mass spectrum peaks consistent with a propanol (this is actually propan-2-ol):
    • 60 - parent ion M
    • 59 - parent ion less one hydrogen, M - H
    • 45 - parent ion less CH3 group, M - CH3
    • 43 - parent ion less OH group, M - OH
    • 15 - methyl group, CH3
  8. The NMR spectrum for propan-2-ol contains three major peaks. From right to left: one peak (of relative size 6) for the six equivalent methyl protons, a second peak (of relative size 1) from the hydroxyl proton, and a third peak (of relative size 1) from the proton attached to C2. These occur in this order due to the deshielding effect of the oxygen nucleus. The methyl protons are split into a doublet by coupling to the C2 proton, and the C2 peak is split into a heptuplet (7) by coupling to the six methyl protons.

    NMR spectrum for propan-2-ol with three main peaks - methyl, methylidene, hydroxyl.