Question

A method used by the Environmental Protection Agency (EPA) for determining the concentration of ozone in air is to pass the air sample through a "bubbler" containing sodium iodide, which removes the ozone according to the following equation: O3(g)+2NaI(aq)+H2O(l)→O2(g)+I2(s)+2NaOH(aq)

Part A) How many moles of sodium iodide are needed to remove 5.95×10⁻⁶ mol O3?

Part B) How many grams of sodium iodide are needed to remove 2.1 mg of O3?

Answer 1

Part A :

O3(g) + 2NaI(aq) + H2O(l) ---------------> O2(g) + I2(s ) + 2NaOH(aq)

from the equation :

for 1 mol of O3   ----------------------> 2 moles of NaI needed

5.95×10⁻⁶ mol O3 --------------------->   ??

moles of NaI needed = 5.95×10⁻⁶ x 2 / 1

                                   = 1.19 x 10^-5 moles

moles of sodium iodide are needed = 1.19 x 10^-5 moles

Part B)

mass of O3 = 2.1 mg = 2.1 x 10^-3 g

O3(g) + 2NaI(aq) + H2O(l) ---------------> O2(g) + I2(s ) + 2NaOH(aq)

48 g of O3 needed --------------------> 299.78 g of NaI

2.1 x 10^-3 g need ----------------------> ??

mass of NaI needed = 2.1 x 10^-3 x 299.78 / 48

                                 = 13 mg

grams of sodium iodide are needed = 13 mg