A hydrate of barium chloride has the formula BaCl subscript 2 dot XH subscript 2 O.If a 1.055g sample of the hydrate contains 0.157g H2O, what is the "X" in the formula?
g BaCl2 (without the H2O) = 1.055-0.157 = 0.898
mols BaCl2 = grams/molar mass = ?
mols H2O = grams/molar mass = ?
Now find the ratio of 1 mol BaCl2 to that of H2O. The easy way to do that is to divide the mols BaCl2 by itself (which MAKES it 1.00), then divide the mols H2O by the same BaCl2 number. Round to a whole number and that will be x.
Thanks so much!
You should have obtained BaCl2.2H2O
To find the value of "X" in the formula BaCl2 · XH2O, we need to determine the number of moles of water present in the hydrate and use stoichiometry to find the ratio of moles between water and BaCl2.
1. Calculate the moles of water (H2O):
- Mass of H2O = 0.157 g
- Molar mass of H2O = 18.015 g/mol
- Moles of H2O = Mass of H2O / Molar mass of H2O
2. Calculate the moles of BaCl2:
- Mass of BaCl2 = Mass of the hydrate - Mass of H2O
- Mass of the hydrate = 1.055 g
- Moles of BaCl2 = Mass of BaCl2 / Molar mass of BaCl2
3. Find the ratio between moles of water and BaCl2:
- Ratio = Moles of H2O / Moles of BaCl2
The value of "X" can be determined by finding the ratio of moles between water and BaCl2.
Note: It is important to use the correct molar masses for BaCl2 and H2O in these calculations.