Answer:
0.2 moles
Step-by-step explanation:
To find the number of moles of solute in a solution, you can use the formula: moles of solute = concentration (in molarity) x liters of solution. In this case, the concentration of the calcium chloride (CaCl2) solution is 2.0 M, and the volume of the solution is 250 ml. To convert the volume from milliliters to liters, you need to divide by 1000, so the solution's volume is 0.25 L.
Now we can substitute the values into the formula:
moles of solute = 2.0 M x 0.25 L = 0.5 moles.
but we need to remember that calcium chloride is a salt composed of two ions (Ca2+, Cl-), so the number of moles of CaCl2 is half the number of moles of calcium ions and chloride ions. Therefore, the number of moles of solute in 250ml of 2.0m CaCl2 is 0.5/2 = 0.2 moles.