Chemistry and Chemical Reactivity (9th Edition)

Published by Cengage Learning
ISBN 10: 1133949649
ISBN 13: 978-1-13394-964-0

Chapter 2 Atoms, Molecules, and Ions - Study Questions - Page 95d: 78


a) Aspirin: $1.80\times10^{-3}\ mol$ $NaHCO_3$: $4.315\times10^{-2}\ mol$ Citric acid: $5.205\times10^{-3}\ mol$ b) $1.08\times10^{21}\ molecules$

Work Step by Step

Atomic weights (g/mol): $C: 12.011,\ H: 1.008,\ O: 15.999,\ Na: 22.990$ Molar masses: Aspirin ($C_9H_8O_4$): $9\times12.011+8\times1.008+4\times15.999=180.2\ g/mol$ $NaHCO_3$: $22.990+1.008+12.011+3\times15.999=84.01\ g/mol$ Citric acid ($C_6H_8O_7$): $6\times12.011+8\times1.008+7\times15.999=192.1\ g/mol$ a) Number of moles Aspirin: $324\times10^{-3}\ g\div180.2\ g/mol=1.80\times10^{-3}\ mol$ $NaHCO_3$: $1904\times10^{-3}\ g\div84.01\ g/mol=4.315\times10^{-2}\ mol$ Citric acid: $1000\times10^{-3}\ g\div192.1\ g/mol = 5.205\times10^{-3}\ mol$ b) Number of molecules of aspirin: $1.80\times10^{-3}\ mol\times6.022\times10^{23}\ molecules/mol=1.08\times10^{21}\ molecules$
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