Hi, Mr. Farabaugh. I have a question about question 3, part d. When determining the rate constant k for the reaction, should the rate used be 1/2 of the initial formation of Cl- since it has a coefficient of 2 in the balanced equation? There have been discussions of this problem in the AP Chemistry facebook group and I am now confused as to what is correct. Can you please clarify for me?
@@danashull6640 I think that the value of the rate constant (k) from the rate law assumes that there is only one value for “rate of reaction “ under a particular set of conditions in a certain trial (which takes into account the initial concentrations of each reactant, the initial temperature, and the order with respect to each reactant in the rate law). In general, it is much easier to define the rate of a reaction in terms of the rate of change for a substance that has a coefficient of “1” in the balanced equation. In that particular question you are referring to, I wasn’t focusing on the fact that chloride ion has a coefficient of “2” and I simply referred to the rate of the reaction in terms of rate of formation of the chloride ion.
@@danashull6640 On an actual free response question on the AP Chemistry exam, the question would be written in such a way to be very clear and straightforward. The people who write those kinetics questions do not intend to play “gotcha” when they ask about the rate of the reaction or the value of the rate constant. Therefore you can assume that your understanding of how to determine the order with respect to each reactant, how to write the rate law, and how to calculate the vale of the rate constant (k) would not be blocked or rejected by a certain subtle detail such as “We asked you for the rate of formation of a product that had a coefficient of “2” and we were trying to trick you…”
@@mrfarabaugh Thank you so much! The video on AP Classroom for 5.2 had a question that the presenter focused on this minutia for determining the value of k for the reaction, not for the appearance for NO2 in the reaction that was in the data table. The NO2 has a coefficient of 2 in the equation. I felt that a video from the college board should not do that and I hope that they won't try to trick students on the AP exam with a question like that.
Your videos are the reason I got a perfect score on my last chemistry test for my AP Chem class. Every chemistry student should watch these videos!
Hi, Mr. Farabaugh. I have a question about question 3, part d. When determining the rate constant k for the reaction, should the rate used be 1/2 of the initial formation of Cl- since it has a coefficient of 2 in the balanced equation? There have been discussions of this problem in the AP Chemistry facebook group and I am now confused as to what is correct. Can you please clarify for me?
@@danashull6640
I think that the value of the rate constant (k) from the rate law assumes that there is only one value for “rate of reaction “ under a particular set of conditions in a certain trial (which takes into account the initial concentrations of each reactant, the initial temperature, and the order with respect to each reactant in the rate law). In general, it is much easier to define the rate of a reaction in terms of the rate of change for a substance that has a coefficient of “1” in the balanced equation.
In that particular question you are referring to, I wasn’t focusing on the fact that chloride ion has a coefficient of “2” and I simply referred to the rate of the reaction in terms of rate of formation of the chloride ion.
@@danashull6640
On an actual free response question on the AP Chemistry exam, the question would be written in such a way to be very clear and straightforward. The people who write those kinetics questions do not intend to play “gotcha” when they ask about the rate of the reaction or the value of the rate constant. Therefore you can assume that your understanding of how to determine the order with respect to each reactant, how to write the rate law, and how to calculate the vale of the rate constant (k) would not be blocked or rejected by a certain subtle detail such as “We asked you for the rate of formation of a product that had a coefficient of “2” and we were trying to trick you…”
@@mrfarabaugh Thank you so much! The video on AP Classroom for 5.2 had a question that the presenter focused on this minutia for determining the value of k for the reaction, not for the appearance for NO2 in the reaction that was in the data table. The NO2 has a coefficient of 2 in the equation. I felt that a video from the college board should not do that and I hope that they won't try to trick students on the AP exam with a question like that.