ch42-p061 - 61. (a) The mass of a 238U atom is (238...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
61. (a) The mass of a 238 U atom is (238 u)(1.661 × 10 – 24 g/u) = 3.95 × 10 – 22 g, so the number of uranium atoms in the rock is N U = (4.20 × 10 – 3 g)/(3.95 × 10 – 22 g) = 1.06 × 10 19 . (b) The mass of a 206 Pb atom is (206 u)(1.661 × 10 – 24 g) = 3.42 × 10 – 22 g, so the number of lead atoms in the rock is N Pb = (2.135 × 10 – 3 g)/(3.42 × 10 – 22 g) = 6.24 × 10 18 . (c) If no lead was lost, there was originally one uranium atom for each lead atom formed by decay, in addition to the uranium atoms that did not yet decay. Thus, the original
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 05/19/2011 for the course PHY 2049 taught by Professor Any during the Spring '08 term at University of Florida.

Ask a homework question - tutors are online