How large is a mole? - Journal of Chemical Education (ACS

This problem is designed to demonstrate to students the size of a mole. Keywords (Audience):. High School / Introductory Chemistry. Keywords (Feature)...
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edited bv: RON DELORENZO Middle Georgia College

Cochran. Georgia 31014

How Large Is a Mole? Irving R. Tannenbaum

Angeles College Culver City, CA 90230 Many techniques have been devised to demonstrate how enormously large a number Avogadro's number is.' We illustrate this to first-year chemistry students by assigning them the following problem, which is to be solved hy the unit-factor method: West LO$

exactly 1million dollars per second since that time. When did the money run out? If it did not run out, how muchremainsnow, after the passage of 4.5 billion years? The calculation gives the answer that the money has not yet run out. Indeed, after 4.5 billion years, a t the rate of 1 million dollars per second, only 0.24 mol of dollars have been given away! The students find this problem to be satisfying and are usually greatly impressed with the size of a mole.

A mole of dollars was created at the time that the Earth was formed, 4.5 billion years ago. It was given away at the rate of

Volume 67

Number 6

June 1990

481