Small molecules with $\mathrm{C}=\mathrm{C}$ double bonds, called monomers, can join with one another to form long chain molecules called polymers. 'Thus, acrylonitrile, $\mathrm{H}_2 \mathrm{C}=\mathrm{CHCN}$ , polymerizes under appropriate conditions to give polyacrylonitrile, a common starting material for producing the carbon fibers used in composites. Repeating unit Polyacrylonitrile (a) Write electron-dot structures for acrylonitrile and polyacrylonitrile, and show how rearranging the electrons can lead to formation of the polymer. (b) Use the bond dissociation energies in Table $7.1$ to calculate $\Delta H$ per $\mathrm{H}_2 \mathrm{C}=\mathrm{CHCN}$ unit for the conversion of acrylonitrile to polyacrylonitrile. Is the reaction endothermic or exothermic?

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chemistry

Plants synthesize the sugar dextrose according to the following reaction by absorbing radiant energy from the sun (photosynthesis).

6 \mathrm{CO}_2(g)+6 \mathrm{H}_2 \mathrm{O}(g) \rightleftharpoons \mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6(s)+6 \mathrm{O}_2(g)

Will an increase in temperature tend to favor or discourage the production of $\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6(s)$ ?

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computer science

The following statement should determine if x is not greater than 20. What is wrong with it?

if (!x > 20)

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health

Select the three factors that are evident when a healing relationship develops between nurse and patient.

The nurse being able to realistically mobilize hope for the patient
The patient being able to share fears of loss with significant others
Finding an interpretation or understanding of the patient's illness that is acceptable to the patient
Understanding your own beliefs about spirituality
Helping the patient use spiritual resources that he or she chooses

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