You wish to prepare a 10% CaCl2 solution. Only CaCl2 * 10H2O is availalbe. How many grams of the hydrated compound are required for 250ml of the reagent? Ca=40 Cl=35.5

If this is 10% by mass (w/w) you can't do it unless you know the density. Is this 10% w/w or 10% w/v? If 10% w/v, which I suspect, convert 10 g CaCl2 to CaCl2.10H2O and that many g in 100 mL will be 10% CaCl2. You need 250 mL; therefore, you will need 2.5 times that amount.

How do I convert 10 g CaCl2 to CaCl2.10H2O?

To prepare a 10% CaCl2 solution using CaCl2 * 10H2O, you need to determine the amount of the hydrated compound required.

Step 1: Calculate the molecular weight of CaCl2 * 10H2O:
CaCl2: 1 * 40 + 2 * 35.5 = 110
10H2O: 10 * (2 * 1 + 16) = 180

Total molecular weight: 110 + 180 = 290 g/mol

Step 2: Determine the amount of CaCl2 * 10H2O needed for 250 ml of the reagent:
To calculate this, you can use the formula:
Amount (g) = Volume (ml) * Concentration (g/ml)

Given:
Volume = 250 ml
Concentration = 10%

We need to convert the concentration from percentage to g/ml.
10% means 10 g of CaCl2 per 100 ml of solution.
Therefore, the concentration of CaCl2 in g/ml is 10 g / 100 ml = 0.1 g/ml.

Now, multiply the volume by the concentration:
Amount (g) = 250 ml * 0.1 g/ml = 25 g

Thus, you would need 25 grams of CaCl2 * 10H2O for 250 ml of the reagent.

To prepare a 10% CaCl2 solution, we need to determine the mass of the hydrated compound (CaCl2 * 10H2O) required for 250ml of the reagent.

To find the mass, we need to consider the molar mass of the hydrated compound.

The molar mass of CaCl2 = (40 g/mol for Ca) + (2 * 35.5 g/mol for Cl) = 40 + 71 = 111 g/mol.

The molar mass of H2O = (2 * 1 g/mol for H) + (16 g/mol for O) = 18 g/mol.

The molar mass of CaCl2 * 10H2O = (111 g/mol for CaCl2) + (10 * 18 g/mol for H2O) = 111 + 180 = 291 g/mol.

Now, we can calculate the mass of the hydrated compound needed for 250ml of the reagent.

To find the mass in grams, we can use the following formula:

Mass (g) = Volume (ml) * Concentration (g/ml)

Given that the concentration is 10% and the volume is 250ml:

Mass (g) = 250ml * 0.1 (g/ml) = 25g

Therefore, you would need 25 grams of the hydrated compound (CaCl2 * 10H2O) to prepare 250ml of a 10% CaCl2 solution.