Use arguments based on resonance and electronegativity effects to explain the trend in carbonyl IR stretching frequencies from higher frequency for esters and carboxylic acids to lower frequencies for amides. (Hint: Use the range of carbonyl stretching frequen- cies for aldehydes and ketones as the "base" frequency range of an unsubstituted car- ponyl group and consider the influence of electronegative atoms on the carbonyl group and/or atoms that alter the resonance hybrid of the carbonyl.) What does this suggest bout the arbonyl group? way the nitrogen atom influences the distribution of electrons in an amide

Which do you expect to have a more intense and concentrated “hot spot” of negative charge: methoxide ion or bicarbonate ion? Explain.

Which one of the following statements from Chapter 8 and 18 is FALSE? O For a compound to be classified as aromatic, it must have an odd number of pairs of r-electrons and must be fully conjugated, cyclic and planar. O Inclusion of heteroatoms as part of the conjugated ring system renders the molecule to be considered non-aromatic. O Benzene is a six-membered ring where the r-electrons are equally shared across all six carbons in the ring and thus it possesses 36 kcal/mol of resonance stabilization energy. O All EAS reactions follow the same three mechanistic steps: (1) generate the electrophile, (2) capture the electrophile to give a carbocation intermediate, and (3) loss of a proton to regain aromaticity.

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What functional group is evidenced by the IR spectrum shown? carboxylic acid O ketone O ester O aldehyde

Is the molecule aromatic, antiaromatic, or non-aromatic? Why?

Compounds P and Q can undergo a Diels-Alder reaction to form two regioisomeric products R and S as shown in Figure 5. OMe P H C8H1202 R C8H1202 S Figure 5 Draw the chemical structures of regioisomeric compounds R and S. (ii) Using possible resonance contributors of P and Q predict which of the two regioisomers will be favoured in the reaction. (iii) Using curly arrows, draw the mechanism for the reaction of P and Q to form the dominant regioisomer you have predicted in your answer to part (ii) above.

(a) In one of the two boxes below, draw a wedge and dashed wedge structure (picture) of CH3Cl that best illustrates the geometry about the central atom. In the other box, draw another picture of the model from a different angle (viewpoint). (b) In CH3Cl, are the three hydrogen atoms equivalent (i.e., do they have identical environments with respect to the other atoms adjacent to themselves)? Briefly explain the evidence for your answer

Determine α' and α for a molecule that experiences a Debye bond energy of -2 aJ being at a distance of 0.1 nm from a molecule of acetic acid

3. Answer ALL parts of this question "Surfactant" is a portmanteau -a word that is a contraction using parts of two or more other terms. What are the words that combine to form (a) 'surfactant'? Utilising a classification system that is based on chemical structure, identify any ONE type of surfactant. There is no need to identify a particular molecule or give a structure. (c) Identify and briefly evaluate a problem found with this type of sufactant