unit 3 Flashcards
1
Q
aqueous solutions of sodium iodide become yellow in the presence of oxygen during to the slow production of iodine.
one suggested reason for this is that a low concentration of hydrogen ions in the solution produces iodine according to the equation below:
4H+ (aq) + 4I- (aq) + O2 (aq) ⇌ 2I2 (aq) + 2H2O (l)
use Le Chatelier’s principle to suggest a reagent that you could add, apart from water, to decrease the amount of yellow iodine present. explain your choice [2]
A
- add a small ‘amount’ of an alkali / sodium hydroxide / NaOH / OH- ions
- this would remove / react with hydrogen ions giving water, shifting the position of equilibrium to the left (removing iodine)
