type it no writing 285 K. Given that the and . onistat pressure of 3.23 atm, its
ID: 693230 • Letter: T
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type it no writing
285 K. Given that the and . onistat pressure of 3.23 atm, its temperature increases from 260 K to ressure is 29.4JK- mor) calculaté q, AH molar heat capacity of Q2 at constant p 3. Some polymers can form liquid crystal mesophases with unusual physical properties. For example, liquid crystal Kevlar (as following picture) is strong enough to be the material of choice tor vests and is stable at temperatures up to 600 K. What molecular interactions contribute to the formation, thermal stability, and mechanical strength of liquid crystal mesophase in Kevtar? (5%) From their atomic numbers and mass numbers, decide whether the following nuclei are likely to ha zero, half-integral or integral spin: (e) 1"o, (b) 10B, (c) 13c, (d) N, (e)F (10%, each 2Explanation / Answer
3. THe Kevlar can be synthesised from the condensation polymerisaton reaction of the 1,4-phenylene-diamine (para-phenylenediamine) with terephthaloyl chloride . The amazing tensile strength of the polymer can be stemed from the H-bonding between the N-H and the O of the CO in the neighbouring strand. There are also additional pi-stacking from the neighbouring strands of polymer chain from the aromatic benzene rings .
For the Odd mass number and odd/even atomic number has the spin half integral , for even mass number and even atomic number the spin is zero and for the even mass number and the odd atomic number the spin would be zero.
(a) 18 O is having zero spin.
(b) 10 B is having +3 spin.
(c) 13C is having 1/2 spin.
(d) 14 N is having 0 spin.
(e) 19 F is having spin of 1/2.
THe half integral neuclus is NMR active.
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