This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: Chemistry 2090 Stable Isotopes? Homework 3 Additional Question A Set of Answers In natural abundance, 98.9% of all C atoms are the isotope 12 C, and the remainder, 1.1%, are the isotope 13 C. Assume, contrary to fact, that these atoms are randomly distributed throughout all of the carbon-containing compounds on earth. 1. You are given a collection of molecules of carbon dioxide, CO 2 . What percent of them contain exactly 1 13 C atom? There is 1 C atom per CO 2 molecule. So 1.1% of the molecules of CO 2 will contain exactly 1 13 C atom. 2. The carbon dioxide is used to make a new molecule, a sugar, which is subsequently fermented to form ethanol with chemical formula C 2 H 6 O. What fraction of the ethanol molecules contain exactly 1 13 C atom, and what fraction contain 2 13 C atoms? Ethanol contains 2 13 C atoms. The likelihood that the 1st C atom is 13 C is 1.1%; the likelihood that the second is 1.1%; that both are 13 C is 1 . 1% 1 . 1 / 100 = 0 . 0121% . The likelihood that neither...
View Full Document