posted by j .
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?