Three processes that have been used for the industrial...

Three processes that have been used for the industrial manufacture of acrylonitrile $\left(\mathrm{CH}_{2} \mathrm{CHCN}\right)$, an important chemical used in the manufacture of plastics, synthetic rubber, and fibers, are shown below. Use bond energy values (Table 8.4) to estimate $\Delta H$ for each of the reactions.

Three processes that have been used for the industrial manufacture of acrylonitrile $\left(\mathrm{CH}_{2} \mathrm{CHCN}\right)$, an important chemical used in the manufacture of plastics, synthetic rubber, and fibers, are
shown below. Use bond energy values (Table 8.4) to estimate $\Delta H$ for each of the reactions.

Key Concepts

Bond Dissociation Energy

Bond dissociation energy refers to the energy required to break a specific chemical bond in one mole of gaseous molecules. This concept is critical when estimating the overall energy changes in a reaction, as it quantifies the energy needed to break bonds in the reactants and the energy released during the formation of new bonds in the products.

Reaction Enthalpy Calculation

This concept involves determining the net heat change (?H) of a chemical reaction by accounting for the energy absorbed in breaking bonds and the energy released in bond formation. The calculation typically follows the formula ?H = (total energy required to break bonds) - (total energy released from forming bonds), often utilizing tabulated bond energy values.

Industrial Chemical Synthesis

Industrial chemical synthesis refers to the large-scale production of chemical compounds. In the context of acrylonitrile production, understanding the energetics of reactions is important for optimizing reaction conditions, improving process efficiency, and ensuring a safe and economically viable manufacturing route.

Transcript

00:01 So in this video we're going to go over question 162 from chapter 8, which says three processes that have been used for the industrial manufacturer of acrylonitrile, ch2chn, an important chemical used in the manufacture of plastic, synthetic rubber, and fibers are shown below.

00:16 Use bond energy values from table 8 .5 to estimate delta h for each of the reactions.

00:23 So the first reaction is actually a two -step reaction, so i've written the first step in the reaction here.

00:31 So let's take inventory of what bonds we're breaking and what bonds we're making.

00:35 Well, we're breaking this carbon oxygen bond, and we're also breaking this carbon hydrogen bond.

00:43 And then this oxygen is going to end up bonding to that hydrogen.

00:48 So we're forming an oh bond.

00:51 And we're also forming a carbon -carbon bond because this cn ends up bonded to this carbon.

00:58 So this cn is going to bond to this carbon.

01:03 So i'm breaking my carbon -oxygen bond.

01:06 I'm breaking a carbon -hydrogen bond.

01:10 I'm forming an oxygen -hydrogen bond and a carbon -carbon bond.

01:14 Notice that my bond energies for the bonds i'm breaking are written positive, and the bond energies for the bonds i'm forming are written negative.

01:22 This is because when you're breaking a bond, it costs energy.

01:26 You have to put energy into it to break a bond.

01:30 But to form a bond, you release energy.

01:33 So when you were forming a bond, the bond energy is negative.

01:36 So we add all of these together to get our delta h, and it ends up being negative 43 kilojoules per mole for the first step.

01:45 And here i've written the second step in the reaction.

01:48 So what bonds are we breaking and what bonds are we making? well, we don't have this oh group on this molecule, so we're breaking this carbon -oxygen bond.

01:58 And we also have one more hydrogen atom on this carbon atom than we do in the product.

02:05 So we're also breaking a carbon hydrogen bond.

02:08 And then our other product is water.

02:11 So this oh group is going to form a bond with that hydrogen atom that we broke off to form water.

02:21 So we're breaking a co bond and a ch bond, and we're forming an oh bond.

02:28 So if we add that all together, we get delta h, and it's 304 kilojoules per mole...

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