The molecular weight of an organic compound was found by mass spectrometry to be 70.042 11. Is the sample C5H10, C4H6O, or C3H6N2? Exact masses of elements are: 1.007 825 (1H); 12.000 00 (12C); 14.003 074 (14N); 15.994 915 (16O).

Video transcript

Hey everyone, we're told using mass spectrometry, the molecular weight of an organic compound was determined to be 84.68748, identify whether the molecular formula of the compound is C five H 80. C four H eight N two or C six H 12. And were asked to use the following masses first. Let's go ahead and determine the molar masses of each of these formulas. Starting with cyclo pence. In, in, We're going to take five of our carbon and we're going to multiply this by its mass of 12.000000. Next we're going to do the same thing for hydrogen. So we're going to add eight of hydrogen times its mass of 1.007825. And lastly with oxygen, we're going to take our one oxygen and times this by its mass of 15. 4915. Now, when we calculate this out, we end up with a value of 84.057515. Now, let's go ahead and move on to tetra hydro prison with a formula of C four H eight N two. This time we have four of carbon and we're going to multiply this by 12.0. And we're going to add and multiply eight times 1.0078-5. And lastly adding our nitrogen in so we have two of nitrogen and we're going to multiply that by its mass of 14.003074. This will get us to a value of 84.068748. And lastly calculating the mass of cyclo hexane. Own we have C six H 12. We're going to take six from carbon and multiply it by its mass of 12 point oh oh oh oh oh. And lastly adding in those hydrogen, we have 12 of hydrogen and we're going to multiply it by its mass of 1.007825. This will get us to a total mass of 84.093900. Now, comparing these values, we can see that our tetra hydro prison had the same mass as the organic compound we had determined in our questions them. So our answer here is going to be C4 HAN two. Now, I hope that made sense. And let us know if you have any questions