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: 23 23 40.08 1 6.656 10 / 1 6.022 10 g mol g atom mol atom- = 23 20 6.656 10 741 4.932 10 1 g atoms g atom-- = CHEMISTRY 103A, Sections 7-10 Problem Set 2: 12 Points Answer Key Problem 1. What is the weight in grams of one mole of calcium (Ca)? Use the 4 sig fig value in your textbook for the atomic weight. 40.08 g Problem 2. What is the weight in grams of one atom of calcium ? The result from problem 1 is the mass of one mole of calcium. The units are formally g/mol. One mole of an element comprises Avogadros number of atoms. The units of the answer to problem 2 should be g/atom: Problem 3. What is the weight in grams of exactly 741 (counting number) calcium atoms ? This is the answer to problem 2 multiplied by 741. The units should be grams : Notice that since 741 is a counting number , i.e. exact, the answer should have four, not three, significant figures. Problem 4. How many moles of calcium is represented by the 741 (counting number) calcium atoms?...
View Full Document