A reaction A + B¡C obeys the following rate law: Rate = k3B42. (a) If [A] is doubled, how will the rate change? Will the rate constant change?

Video transcript

Welcome back everyone in this example, we're given the rate law for the reaction of xy producing Z. As a product where our rate law says that we have our rate constant K. Times the concentration of our reacting X. To the second power. And that is multiplied by the concentration of our react and why to the first power? Now, what these exponents mean we should recall is that X. Is second order with respect to our reaction. And why is first order with respect to our reaction. We need to determine what the change in our rate law will be when our concentration of why is tripled. Were asked whether the rate constant will change when the concentration of why changes. So we have two questions to answer here and what we should recognize is that according to the prompt, we have the following rate law where our rate is equal to our rate constant K. Times the concentration of are reacting X, which is second order times the concentration of reactant Y. Which is first order. And what we can determine based on this rate law is that rate which is on the left hand side of our equal sign here in our expression is going to be directly proportional to the concentration of our reactant. And so we can say that therefore our rate is directly proportional to the concentration of X And to the concentration of our 2nd reactant. Y. So to answer our first question here, we can say that for question one, if we take our concentration of our reactant Y and we triple it by multiplying it by three because our concentration of our reactant, why is directly proportional to our rate of our reaction. We would have to express our rate law where our rate is also multiplied by three and set equal to the rate constant K. Times the concentration of our x. Reactant times our concentration of ry reactant times three as well. And so we can say that thus when our concentration of why is tripled, our rate is tripled. And so this would be our first answer here for part one of the prompt and now we have part two to answer in the prompt. And sorry part two is over here will our rate constant K. Change when our concentration of wide changes. And so for part two of the prompt will answer that here in red. We would agree that analyzing our rate law given in the prompt, our rate constant K. Is on the same side of the concentration of our reactant. And so our rate constant and our concentration of reactant are both on the right hand side of our equal sign here for our rate law. And so that means that when one of these variables changes, it won't affect. The other variables here are other variables will remain constant. And so we can say that for part two of the prompt, if our concentration of reacting, why changes our rate constant will not change. And that is also due to the fact that it's a constant. and so it should always remain the same. And so this would be our second and final answer to complete this example. So everything highlighted in yellow in our solution are our final answers. If you have any questions, please leave them down below, and I will see everyone in the next practice video.