Consider the two reactions:

O + N₂ → NO + N E_a = 315 kJ/mol

Cl + H₂ → HCl + H E_a = 23 kJ/mol

a. Why is the activation barrier for the first reaction so much higher than that for the second?

Video transcript

Hey everyone in this example, we need to determine which of the given reactions will have the smallest orientation factor. So we want to recall that the more complex our reactant sare that will correspond to a smaller orientation factor. So looking at our first reaction, we have potassium a nonmetal or sorry, a metal atom reacting with bromine gas, which we were recognized as a non metal to produce potassium bromide. And bro mean, recall that potassium will form a plus one, carry on and bromine because it's in Group seven A will form a minus one, an ion. And so as our products, we have KBR where we have an electron transfer here to form this product, leaving us with our second product, bro, mean, just as an atom alone. And so because we have this electron transfer, we can recognize that this is going to be a harpoon mechanism reaction. And we would consider this to be a fairly simple reaction because we would say are re agents are fairly simple to also identify. So we're just going to rule Choice A out. It should probably have a small orientation. Or sorry, a large orientation factor. But moving onto choice B. We have the reaction where we have two hydrogen atoms that are combining to form our product H. Two or hydrogen gas and we would recognize our attractants are simple. H Adams. And so we would rule this out because we're likely going to just have a large orientation factor. So Choice B can also be ruled out that leaves us with choice C. Where we have hydrogen gas reacting with propane and we're getting a product being propane, we would recognize our reactant here, We have propane and hydrogen gas as more complex re agents. And so we can say therefore, this is going to likely have a small orientation factor. And so to complete this example, that means that choice C. Would be the best answer choice as our final answer, because it was the only reaction that consisted of more complex re agents or reactant that produced the the product propane here, and so it should have the smallest orientation factor based on these complex react ints reacting together. So C is our final answer. If you have any questions, please leave them down below and I will see everyone in the next practice video.