calculate the value of water that is needed to dissolve 1.11 g of CaCl2 in order to prepare a 0.0250 M CaCl2 solution?
Remember the definitions.
Molarity = # mols/L.
and # mols = g/molar mass.
How many moles CaCl2 do you have in 11.1 g CaCl2. That will be 11.1 g CaCl2/molar mass CaCl2.
Then #mols = M x L.
You have M and you have mols, calculate L.
The procedure suggested by DrBob 222 will give the correct answer to the question. However, the wording of the question itself could be improved. It might be:
"Calculate the total volume of solution (water + CaCl2) when a 0.0250 M CaCl2 solution is prepared by dissolving 1.11 g of CaCl2 in a small volume of water and diluting to the calculated volume.".
The amount of water added cannot be calculated with complete precision since the volume of the solution includes both, water and calcium chloride.
GK is correct; the problem could have been worded more correctly. I assumed you were asking for the solution. Also, I note that I made an error in typing. It isn't 11.1 g CaCl2 but 1.11 g CaCl2.
To calculate the value of water needed to dissolve 1.11 g of CaCl2 in order to prepare a 0.0250 M CaCl2 solution, you need to consider the molar mass of CaCl2 and use the relationship between moles, molarity, and volume to determine the amount of water needed.
First, let's find the number of moles of CaCl2:
Molar mass of CaCl2 = 40.08 g/mol (for Ca) + (2 * 35.45 g/mol) (for Cl)
= 40.08 g/mol + 70.90 g/mol
= 111.98 g/mol
Now, calculate the number of moles of CaCl2:
moles of CaCl2 = mass / molar mass
= 1.11 g / 111.98 g/mol
= 0.0099 mol
Next, use the relationship between moles, molarity, and volume:
moles = molarity * volume
0.0099 mol = 0.0250 M * volume
Rearranging the equation:
volume = moles / molarity
volume = 0.0099 mol / 0.0250 M
volume = 0.396 L
Therefore, you would need approximately 0.396 liters (or 396 milliliters) of water to dissolve 1.11 g of CaCl2 in order to prepare a 0.0250 M CaCl2 solution.