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# Exponential decay and semi-log plots

Using exponential decay equation to solve for relationship between k and half-life. Using semi-log plot to get graph of a straight line with slope of -k.  Created by Jay.

## Want to join the conversation?

• Does the x-intercept tell us anything useful in this case?
• On a linear plot, the x-intercept is the value of x when y = 0. In this case, the x-intercept would be the value of time when the ln N = 0, which only occurs when N=1.
• how do you get n as a factor
• N, as in the amount of the substance in question, will be given in the question or it will be the unknown you are trying to find using this equation.
• At negative sign with constant indicate to what?
• your question doesn't seem complete. Well, as far as i understood lambda is an arbitrary constant which is unique to each element and it can be easily derived from it's half life as mentioned by Jay, (lambda=.693/half life) [ kindly refer to the video as what i wrote might be wrong.
So yes, i believe you were referring to lambda which is a constant unique to each element which we can use in the equation, N=N(nought) * e^-(lambda)*t.

Hope this helps.
(1 vote)
• At what does the negative sign represent?
• It's first order kinetics and the amount of radioactive substance is decreasing with time.
(1 vote)
• What is nuclear?
• Literally relating to the nucleus of an atom. I'd suggest you check the previous videos in order to get a better understanding of what is meant by nuclear chemistry :)
• Does the x-intercept tell us anything useful in this case?
(1 vote)
• Is first order kinetics directly related with the exponential decay equation?