In: Chemistry
Zeolite A, Na12[(AlO2)12(SiO2)12] · 27H2O, is used to soften water by replacing Ca2+ and Mg2+ with Na+. Hard water from a certain source is 4.20 × 10−3M Ca2+ and
8.20 × 10−4M Mg2+, and a pipe delivers 2.20 × 104 L of this hard water per day. What mass (in kg) of zeolite A is needed (in kg) to soften a day's supply of the water? (Assume zeolite A loses its capacity to exchange ions when 85.0% mol of its Na+ has been lost.)
(Enter your answer in scientific notation.)
Per day supply of hard water = 22000L
Concentration of Ca2+ = 0.00420mol /L
Total mole of Ca2+ = 22000 × 0.00420= 92.4mol
Molar mass of Ca2+ = 40.08g/mol
Mass of Ca2+ in hard water = 92.4×40.08g = 3703.4g
Concentration of Mg2+ = 0.000820mol/L
Total mol of Mg2+ = 0.000820 × 22000=18.04
Molar mass of Mg2+ = 24.31g/mol
Mass of Mg2+ in Hard water = 24.31g × 18.04 = 438.6g
Molar mass of Zeolite A = 2190g/mol
No of mole of Ca2+ removed by 1 mole of Zeolite A = 6
Mass of Ca2+ removed by 2190g of Zeolite A = 240.48g
Mass of Zeolite A required to remove 3703.4g of Ca2+ = 33.73kg
If consider Zeolite efficiency is 85%
Mass of Zeolite A to remove Ca2+ = 39.68kg
No of mole of Mg2+ removed by 1 mole of ZeoliteA = 6
Mass of Mg2+ removed by 2190g of ZeoliteA = 145.86g
Mass of Zeolite required to remove 438.6g of Mg2+= 6.59kg
Considering the 85% as the efficient of Zeolite A
Mass of Zeolite A required to remove Mg2+ = 7.75kg
Total mass of Zeolite A required = 39.68kg + 7.75kg = 47.43kg