Chemical Forums

Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: thehyruler on February 26, 2019, 12:36:22 AM

Title: Partial Mass Spectrum of Mystery Compound
Post by: thehyruler on February 26, 2019, 12:36:22 AM

I started Yale's opencourse freshman organic chemistry course and I have a question on the first homework assignment found here: http://chem125-oyc.webspace.yale.edu/125/history99/2Pre1800/SPepysINewton/IsotopeMassSpec.htm

I understand the Pepys/Newton problem but I am confused as to how to determine the number of chlorine atoms there are using the Pepys/Newton problem. If you're unfamiliar, Pepys asked Newton what the probability of rolling one 4 using six tetrahedra versus two 4s using twelve tetrahedra versus three 4s using eighteen tetrahedra. But how do I apply that to determining the number of chlorine atoms there are when given these ratios?

Any help is much appreciated.

Title: Re: Partial Mass Spectrum of Mystery Compound
Post by: JacobAnderson on February 26, 2019, 10:17:29 AM

I will see, if I can find anyone to help you.

Title: Re: Partial Mass Spectrum of Mystery Compound
Post by: AWK on February 26, 2019, 03:42:00 PM

Check from 4 chlorine atoms up
or
recalculate abundance of 35-Cl to 1. Then Newton's binomial will be (1+x)ⁿ and n1^n-1x easily will give you the number of chlorine atoms, even without a calculator (in the scale of the problem from the link you gave).