Chapter 4 - Sections 4.1-4.9 - Exercises - Problems by Topic - Page 188: 54c

$6.898\times10^{-4}M$

To find the molarity we divide the number of moles of solute by the liters of solution. $M= \frac{Moles\ solute}{Liters\ solution}$ So for this problem we get: $12.87mg\ KI\times\frac{1g}{1000mg}\times\frac{1mol\ KI}{166.0g\ KI}=7.753\times10^{-5}mol\\ 112.4mL\frac{1L}{1000mL}\\ \frac{7.753\times10^{-5}mol\ KI}{0.1124L}= 6.898\times10^{-4}M$