Determine the quantity (g) of pure CaCl2 in 7.5 g of CaCl2*9H2O

7.5 g CaCl2*9H2O x (molar mass CaCl2/molar mass CaCl2*9H2O)_

CaCl2=110.98

H2O=18.016

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To determine the quantity of pure CaCl2 (calcium chloride) in 7.5 g of CaCl2·9H2O (calcium chloride dihydrate), you need to consider the molar mass and stoichiometry.

1. Find the molar mass of CaCl2·9H2O:
- Molar mass of calcium (Ca) = 40.08 g/mol
- Molar mass of chlorine (Cl) = 35.45 g/mol
- Molar mass of water (H2O) = 18.02 g/mol
- Total molar mass of CaCl2·9H2O = (40.08 g/mol) + 2(35.45 g/mol) + 9(18.02 g/mol) = 219.08 g/mol

2. Calculate the moles of CaCl2·9H2O:
- Moles = mass / molar mass
- Moles of CaCl2·9H2O = 7.5 g / 219.08 g/mol = 0.034 mol

3. Apply the stoichiometry:
- In the compound CaCl2·9H2O, there is 1 mole of CaCl2 for every mole of CaCl2·9H2O.
- Therefore, the quantity of pure CaCl2 in 7.5 g of CaCl2·9H2O is also 0.034 mol.

4. Determine the mass of pure CaCl2:
- Mass = moles × molar mass
- Mass of pure CaCl2 = 0.034 mol × 110.98 g/mol = 3.78 g

Therefore, the quantity of pure CaCl2 in 7.5 g of CaCl2·9H2O is 3.78 grams.

To determine the quantity of pure CaCl2 in 7.5 g of CaCl2*9H2O, we need to consider the molar mass of calcium chloride dihydrate (CaCl2*2H2O) and the molar mass of water (H2O).

The molar mass of CaCl2*2H2O can be calculated as follows:
1 mol of Ca = 40.08 g/mol
2 mol of Cl = 35.45 g/mol x 2 = 70.90 g/mol
2 mol of H2O = 18.02 g/mol x 2 = 36.04 g/mol
Total molar mass of CaCl2*2H2O = 40.08 g/mol + 70.90 g/mol + 36.04 g/mol = 147.02 g/mol

Now, since CaCl2*2H2O has a molar mass of 147.02 g/mol, we can calculate the quantity of pure CaCl2 in 7.5 g of CaCl2*2H2O using the following equation:

Quantity of pure CaCl2 (g) = (Molar mass of pure CaCl2 / Molar mass of CaCl2*2H2O) x Mass of CaCl2*2H2O

Quantity of pure CaCl2 (g) = (110.98 g/mol / 147.02 g/mol) x 7.5 g
Quantity of pure CaCl2 (g) = 0.754 g

Therefore, there are approximately 0.754 g of pure CaCl2 in 7.5 g of CaCl2*2H2O.