Question

How many moles of Cl^- ions are present in 259 mL of a 0.16 M FeCl₃ solution

Answer 1

The formula tells you that there are 3 mol of Cl⁻ in 1 mol of FeCl₃. So, we must find the moles of FeCl₃.

Proportion:

0.16 mol – 1000 mL

x mol – 259 mL

$x = \frac{0.16 \times 259}{1000}= 0.0414 \;mol$

n(FeCl₃) = 0.0414 mol

n(Cl⁻) $= 3 \times 0.0414 = 0.1242 \;mol$

Answer: 0.1242 mol