Question

Now consider the reaction when 45.0 g NaOH have been added. What amount of NaOH is this, and what amount of FeCl₃ can be consumed by it?

___________mol NaOH available

__________mol FeCl₃ that can react

Answer 1

NaOH mass = 45 g

NaOH molar mass = 40 g /mol

NaOH moles = mass / molar mass

                     = 45 / 40

                     = 1.125

1.125 mol NaOH available

3 NaOH + FeCl3 ---------------------> Fe(OH)3 + 3 NaCl

3 mol NaOH react with --------------------> 1 mol FeCl3

1.125 moles NaOH react with -----------------> x mole FeCl3

x = 1.125 / 3

x = 0.375 mol

0.375 mol FeCl3 that can react

FeCl3 molar mass = 162g /mol

FeCl3 mass = moles x mass

                    = 0.375 x 162

                     = 60.75 g

amount of FeCl₃ can be consumed = 60.75 g