Can someone please please tell me how to calculate the instantaneous rate of a reaction from a graph.?

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Can someone pleaseee tell me how to calculate the instantaneous rate of a reaction from a graph.In the problem they give Consider the following reaction:H2(g) + Br2(g) ---> 2HBr(g)The graph below shows the concentration of Br2(g) as a function of time. The graph is not linear.Part a says to calculate the average rate of the reaction between 0 and 25s. I can do this part. Average rate of change is just (Change in concentration/change in time). But then it asks for the instantaneous rate at 25 seconds, and also at 50 seconds. Now there is not table of values so i can only look at the graph and estimate the concentration at a time. I know that instantaneous rate of change is the slope of the tangent line to that point, but how do i find the slope of a tangent line without using calculus or knowing specific values? The book said something about choosing two values very close to the point of interest, but which two points? like 24 seconds and 26 seconds? in the book they used 30 seconds and 70 seconds to calculate the instantaneous speed at 50 seconds. Is there a general rule?

Demetrius Gusikowski · Accepted Answer

You're pretty much on track. Visualize a line tangent to the function to get the derivative at a point. Since 30 seconds and 70 seconds are both 20 seconds away from 50, it is acceptable to use those. 24 seconds and 26 seconds would be acceptable if you were trying to find 25 seconds, because a 2 second interval is pretty small.The general rule is tangent line is the best, otherwise the line will intersect at two points. You want those two points to be as close together as possible.

Demetrius Gusikowski · Answer

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Demetrius Gusikowski · Answer

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Demetrius Gusikowski · Answer

This Site Might Help You.RE:Can someone please please tell me how to calculate the instantaneous rate of a reaction from a graph.?Can someone pleaseee tell me how to calculate the instantaneous rate of a reaction from a graph.In the problem they give Consider the following reaction:H2(g) + Br2(g) ---> 2HBr(g)The graph below shows the concentration of Br2(g) as a function of time. The graph is not linear.Part a...

Demetrius Gusikowski · Answer

For finding instantaneous rate around 25s, use the two ranges around the point, in this case at time 40 and 10, so you have (.65 - .9)/(40-10) = .0083. The correct answer is .0085, but this answer also works.

Demetrius Gusikowski · Answer

that depends on the reaction. for the reaction A ---> B + C rate = -d[A] / dt = k x [A]^n... where n is the order of the reaction. if n=0 -d[A] / dt = k x [A]^n becomes ∫d[A] = -k∫dt which integrates to [At] - [Ao] = -kt [At] = -kt + [Ao] so a plot of [A] vs t gives you a line with slope = -k in which case.. you can plug in k into this equation rate = k x[A]^0 ********* if n=1, ∫1/[A] d[A] = -k∫dt integrates to ln[A] = -kt + ln[Ao] and a plot of ln[A] vs t gives -k.. and you plug that into rate = k x [A]^1 ******* if n=2 1/[A] = +kt + 1/[Ao] and a plot of 1/[A] vs t gives +k.. and you finish like this rate = k x [A]^2 ********* so without seeing the data or knowing the reaction it's impossible to answer your question.

Demetrius Gusikowski

Can someone please please tell me how to calculate the instantaneous rate of a reaction from a graph.?

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