1.What mass of water could be absorbed from moist air by a 1000.0g sample of a zeolite with the empirical formula Na2Al2Si3O10*2H2O, assuming that the zeolite had been dehydrated first?
2. What mass of Ca2+ could be removed from hard water by a 2000.0g sample of the hydrated zeolite from question 1.
1.
1000g x (2*molar mass H2O/molar mass dehydrated zeolite) = ?
104.7g
To answer these questions, we will need to calculate the amount of water absorbed by the zeolite and the amount of Ca2+ ions that can be removed by the hydrated zeolite.
1. To determine the mass of water absorbed by the zeolite, we need to find the difference in mass between the hydrated and dehydrated forms of the compound. The empirical formula of the zeolite is Na2Al2Si3O10*2H2O, indicating that each unit of zeolite can absorb 2 water molecules.
Using molar masses:
- Molecular mass of Na2Al2Si3O10*2H2O = (2 * 22.99) + (2 * 26.98) + (3 * 28.09) + (10 * 16.00) + (2 * 2.02 * H2O) = 186.31 g/mol
- Molecular mass of Na2Al2Si3O10 = (2 * 22.99) + (2 * 26.98) + (3 * 28.09) + (10 * 16.00) = 468.11 g/mol
The mass of water absorbed by the zeolite can be calculated as follows:
Mass of water absorbed = (molecular mass of Na2Al2Si3O10*2H2O - molecular mass of Na2Al2Si3O10) * (mass of zeolite sample / molecular mass of Na2Al2Si3O10*2H2O)
Substituting the values:
Mass of water absorbed = (186.31 - 468.11) * (1000.0 / 186.31) = -457.85 g
Note: The negative value indicates that the zeolite loses water upon dehydration and does not absorb water from the air.
2. To determine the mass of Ca2+ ions that can be removed by the hydrated zeolite, we need to consider the stoichiometry of the compound. The empirical formula Na2Al2Si3O10*2H2O indicates that for every two units of zeolite, there is one Ca2+ ion.
Using molar masses:
- Molecular mass of Ca2+ = (2 * 40.08) = 80.16 g/mol
The mass of Ca2+ ions that can be removed can be calculated as follows:
Mass of Ca2+ = (mass of hydrated zeolite sample / molecular mass of zeolite) * (1 Ca2+ ion / 2 zeolite units) * (2 * molecular mass of Ca2+)
Substituting the values:
Mass of Ca2+ = (2000.0 / 468.11) * (1 / 2) * (2 * 80.16) = 171.10 g
Therefore, the mass of Ca2+ ions that can be removed from the hard water by the hydrated zeolite is 171.10 g.