On Exam 1, you’ll work some Kinetics problems that require y…
On Exam 1, you’ll work some Kinetics problems that require you to use the “Natural log” function on your calculator. “ln” is the abbreviation for Natural Log. You’ll use this for 1st order Kinetics problems. The formula you’ll be given is: ln[A]t – ln[A]o = -kt It looks scary, but after you practice with it you’ll be okay. In this example, I’m going to give you the following: Final concentration is At = 0.050M Initial concentration is A0 = 1.30M Rate constant is “k” = 0.00350/s Solve for the time in minutes: Plug numbers in to formula: ln[A]t – ln[A]o = -kt ln[0.050] – ln[1.30] = -0.00350t Of course, you can enter the entire calculations at one time…but my hints below are going to show you how to perform each individual calculation: Step 1: Get natural log of 0.050: ln[0.050] Hit ln button on calculator and enter (0.050) … you should get the answer of -2.996 (If you aren’t familiar with natural logs, a little hint…anytime you take the natural log of a number less than 1, you will always get a negative answer. Step 2: Get natural log of 1.30: ln[1.30] Hit ln button on calculator and enter (1.30) … you should get the answer of 0.2624 (and…anytime you take the natural log of a number greater than 1, you will always get a positive answer. Step 3: Perform algebra to solve for “time” -2.996 – 0.2624 = -0.00350(t) -3.258 = -0.00350(t) Divide both sides by -0.00350 to solve for “t” = 930.97 = 931 seconds (Watch your + and – signs. Keep in mind, you should never end up with a negative value for time) Step 4: Solve for minutes: convert answer in #3 to minutes…I think you can do that one yourself 🙂 *** Keep in mind…all the concepts and calculations will be taught to you when we cover Kinetics…I’m just trying to give you practice using the HonorLock Calculator for the Lab Final
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