The first five vibrational energy levels of HCl are at 1481.86, 4367.50, 7149.04, 9826.48, and 12 399.8 \(\mathrm{cm}^{-1}\). Calculate the dissociation energy of the molecule in reciprocal centimetres and electronvolts.
Text Transcription:
cm^-1
C127 Lecture 12 Notes- Aspirin 4-14-16 Essentially: salicylic acid + acetic anhydride + heat = acetylsalicylic acid Decomposes into acetic acid and salicylic acid over time Learning Goals o Use qualitative test to assess purity of a sample o Use melting point determinations to assess purity of a sample o Use Thin Layer Chromatography to assess purity of a sample Safety o All liquid/solid waste should go in waste bottle o Dispose of all glass in broken glass bucket o Make sure melting point apparatus turned off at end Melting Point o Every chemical compound has unique point o Intermolecular forces between molecules in crystal lattice control melting point o Impurities weaken intermolecular forces and lower melting point o Can identify and assess purity of a compound Salicylic acid has different melting point than aspirin- if measured value closer to salicylic’s melting point than aspirin’s, substance decomposed badly Temperature at melting point identifies compound present Size of temperature range over which melting occurs tells about purity of sample- broader range less pure, smaller range (2-3℃) higher purity When given expected melting point, melting should occur within the 2-3℃ range of that value o Ex. Made-up value for to show comparison:
