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Solution The first graph shows two curves with similar characteristics, except f

ID: 700704 • Letter: S

Question

Solution

The first graph shows two curves with similar characteristics, except for a shift in the X-direction. This implies that they should correspond to the same molecule, albeit at different temperatures. Now we know that the curves will be an approximation of A=RT hyperbolic curve. So, curve W represents the higher temperature (20 degrees) and Z the lower temperature (1.6 degrees).

Cis-13-docosenoic acid has a shorter hydrophobic tail compared to trans-13-docosenoic acid. So, Y represents the longer chain and X represents the shorter chain.

Explanation / Answer

**** x-axis = Molecular cross section area [m2/molecule]

w) The /A curves represented by (X), (Y), (Z), (W) are shown above. One pair of curves corresponds to: (i) cis &trans; forms of 13-docosenoic acid, CH3(CH2)7CH-CH(CH211COOH (ii) octadecanoic acid CH3(CH216COOH 1.6°C & 20.0°C Assign the correct curve to each situation and comment on the molecular cross section estimates with relation to the packing of these surfactants