General Chemistry 10th Edition

Published by Cengage Learning
ISBN 10: 1-28505-137-8
ISBN 13: 978-1-28505-137-6

Chapter 3 - Calculations with Chemical Formulas and Equations - Questions and Problems - Page 119: 3.33

Answer

a. Mass of a Na atom = 3.818 x $10^{-23}$ g b. Mass of an N atom =2.326 x $10^{-23}$ g c. Mass of a C$H_{3}$Cl molecule = 8.383 x $10^{-23}$ g d. Mass of a $Hg(NO_{3})_{2}$ formula unit = 5.392 x $10^{-22}$ g

Work Step by Step

Strategy: To calculate the mass of one atom, molecule, or formula unit, we should use:1- Molar mass, that is the mass of one mole of substance 2- relationship of mole and Avogadro's number . a. Mass of Na atom. The atomic mass of Na is 22.989 amu, so the molar mass of Na is 22.989 g/mol. 1 mol Na has Avogadro's number atoms that is 6.02 x $10^{23}$. Mass of a Na atom = $\frac{molar mass Na}{Avogadro's number}$ Mass of a Na atom = $\frac{22.989g}{6.02 \times 10^{23}}$ Mass of a Na atom = 3.818 x $10^{-23}$ g b. Mass of N atom. The atomic mass of N is 14.006 amu, so the molar mass of Na is 14.006 g/mol. 1 mol N has Avogadro's number atoms that is 6.02 x $10^{23}$. Mass of an N atom = $\frac{molar mass N}{Avogadro's number}$ Mass of an N atom = $\frac{14.006g}{6.02 \times10^{23}}$ Mass of an N atom =2.326 x $10^{-23}$ g c. Mass of C$H_{3}$Cl molecule. Molar mass of C$H_{3}$Cl = 12.01 + 3 x 1.007 + 35.45 Molar mass of C$H_{3}$Cl = 50.471 g/mol 1 mol C$H_{3}$Cl has Avogadro's number atoms that is 6.02 x $10^{23}$. Mass of a C$H_{3}$Cl molecule = $\frac{molar mass_{CH_{3}Cl}}{Avogadro's number}$ Mass of a C$H_{3}$Cl molecule = $\frac{50.471 g}{6.02 \times10^{23}}$ Mass of a C$H_{3}$Cl molecule = 8.383 x $10^{-23}$ g d. Mass of $Hg(NO_{3})_{2}$ formula unit. Molar mass $Hg(NO_{3})_{2}$ = 1 AM Hg + 2 AM N + 6 AM O Molar mass $Hg(NO_{3})_{2}$ = 1 X 200.59 + 2 x 14.0067 + 6 x 15.999 Molar mass $Hg(NO_{3})_{2}$ = 324.597 g Mass of a $Hg(NO_{3})_{2}$ formula unit = $\frac{molar mass_{$Hg(NO_{3})_{2}$}}{Avogadro's number}$ Mass of a $Hg(NO_{3})_{2}$ formula unit = $\frac{324.597 g}{6.02 \times10^{23}}$ Mass of a $Hg(NO_{3})_{2}$ formula unit = 53.920 x $10^{-23}$ g Mass of a $Hg(NO_{3})_{2}$ formula unit = 5.392 x $10^{-22}$ g
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