An automotive fuel injector dispenses a fine spray of
gasoline in...

Question

An automotive fuel injector dispenses a fine spray of
gasoline into the automobile cylinder, as shown in the
bottom drawing here. When an injector gets clogged, as
shown in the top drawing, the spray is not as fine or even
and the performance of the car declines. How is this observation
related to chemical kinetics? [Section 14.1]

Accepted Answer

Hey everyone. So today we're being told that stuff burners that are connected to nozzles regulate the steady flow and supply of gas to provide combustion. However, when that nozzle is closed, there's interference and there is poor or incomplete burning as a result. And given the following answer, choices were being asked to find out which is a possible explanation and how it is related to chemical kinetics. Now, one of the most important things about reactions, especially between particles is that we need a few things. We need good temperature for the reaction to proceed. And let's write these down, We need temperature, temp temperature, we need effective collisions and we need good surface area of the reactant. So putting everything aside in this case, we're actually dealing with surface area and here's why while we're dealing with surface area and collision specifically. So when we have a normal nozzle and let's go ahead and draw this out. Just a pretty crude drawing, just imagine this is our nozzle. If it's unclogged, we will get all of these very fine particles that will end up spraying out. And even though the particles are smaller and you might say, oh, that means it wouldn't have as much surface area is a larger particle. Well, we're not talking about individual particles, we're talking about the whole complete concentration of all the particles that are there. So since we have more particles here, it will be more even and they'll be finer, which means there will be more effective collisions and therefore having faster combustion faster combustion. However, if the nozzle is clogged and I'll draw that out too, let's say there's something blocking it here. Well, the particles are going to end up being uneven. You might have some bigger sprays than you might have otherwise. You might have some even smaller ones, but large, likely they're going to be uneven and larger. So even though individual particles might have more surface area, there's actually far less surface area. When considering the entire concentration that's being reacted as such, there will be smaller surface area exposed to oxygen, which means slower combustion. And the answer that supports this is a the clogged nozzle produces uneven and larger particles and reduces the surface area exposed to oxygen with slows down combustion or leads to incomplete combustion. I hope this helps. And I look forward to seeing you all in the next one.

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