Ch.19 - Nuclear ChemistryWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Solution: Uranium-238 undergoes a slow decay step (t1/2 = 4.5×109 yr) followed by a series of fast steps to form the stable isotope 206Pb. Thus, on a time scale of billions of years, 238U effectively decays “di

Problem

Uranium-238 undergoes a slow decay step (t1/2 = 4.5×109 yr) followed by a series of fast steps to form the stable isotope 206Pb. Thus, on a time scale of billions of years, 238U effectively decays “directly” to 206Pb, and the relative amounts of these isotopes are used to find the age of some rocks. Two students derive equations relating number of half-lives (n) since the rock formed to the amounts of the isotopes:

(a) Which equation is correct, and why?

(b) If a rock contains exactly twice as much 238U as 206Pb, what is its age in years?