Question

If all of the SCN- is complexed with Fe3+ to form FeNCS2+ what is the molar concentration of FeNCS2+

Answer 1

Molarity = number of moles X (1000/volume)

number of moles of SCN⁻ = 0 .001 X 3 / 1000 = 3 X 10⁻⁶ moles in the 25 ml of solution

2) SCN⁻ + Fe³⁺ ===> FeNCS²⁺

1 mole SCN⁻ produces 1 mole of FeNCS²⁺

Therefore moles of FeNCS²⁺ in 25 ml = 3 X 10⁻⁶

Molar Concentration of FeNCS²⁺ = (3 X10⁻⁶ )X 1000 / 25 = 1.2 X 10⁻⁴ Moles / liter