## Chemistry and Chemical Reactivity (9th Edition)

Published by Cengage Learning

# Chapter 4 Stoichiometry: Quantitative Information about Chemical Reactions - Study Questions - Page 179l: 134

#### Answer

See answer below.

#### Work Step by Step

Titration 1: Number of moles of $AgNO_3$: $41.00\ mL\times 0.0750\ M=3.075\ mmol$, same as the chloride ion. Concentration: $3.075\ mmol/50.0\ mL=0.0615\ M$ Original solution: $0.0615\ M\times 0.250\ L=0.0154\ mol$ Mass of KCl: $0.0154\ mol\times 74.55\ g/mol=1.15\ g$ Mass percentage: $1.15/4.00\times100\%=28.7\%$ Titration 2: Number of moles of $AgNO_3$: $38.12\ mL\times 0.0750\ M=2.860\ mmol$, same as chloride From the first titration, number of moles of chlorides from perchlorate: $2.860\ mmol-0.0615\ M\times 25.00\ mL=1.322\ mmol$ Concentration: $1.322\ mmol/25.0\ mL=0.0529\ M$ Original solution: $0.0529\ M\times 0.250\ L=0.0154\ mol$ Mass of $KClO_4$: $0.0132\ mol\times 138.54\ g/mol=1.83\ g$ Mass percentage: $1.83/4.00\times100\%=45.7\%$

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