An aqueous solution contains 4.50 g of calcium chloride, CaCl2, per liter. What is the molarity of CaCl2? When calcium chloride dissolves in water, the calcium ions, Ca^+2, and chloride ions, Cl^-, in the crystal go into the solution. What is the molar concentration of each ion in the solution?

I got .0450 M CaCl2. I'm pretty sure that is right, but I don't understand what it means by how to find the molarity of each ion.

I divided by 111.1. Our teacher likes us to use 3 digits when using atomic weight.

Oh wait, is this one like the last one I asked for? I didn't work that one out yet.

Yes, the principle is the same.

But I obtained 4.50/110.983 = 0.04055 which I would round to 0.0406 M.

OK, but 4.50/111 still isn't 0.0450. Perhaps you just made a typo.

To find the molarity of calcium chloride (CaCl2), you need to understand the definition of molarity. Molarity (M) is defined as the number of moles of solute per liter of solution, expressed in moles per liter (mol/L or M).

To calculate the molarity of CaCl2, you need to convert the given mass of CaCl2 to moles. First, you should calculate the molar mass of CaCl2 by adding the atomic masses of its constituent elements:

Molar mass of CaCl2 = (atomic mass of Ca) + 2 × (atomic mass of Cl)
= (40.08 g/mol) + 2 × (35.45 g/mol)
= 110.98 g/mol

Now, you can calculate the number of moles of CaCl2 using the formula:

Number of moles = mass / molar mass

Number of moles of CaCl2 = 4.50 g / 110.98 g/mol
= 0.0406 mol

Finally, divide the number of moles by the volume of the solution (in liters) to obtain the molarity:

Molarity of CaCl2 = 0.0406 mol / 1 L
= 0.0406 M

Therefore, your answer of 0.0450 M for the molarity of CaCl2 appears incorrect. The correct molarity is 0.0406 M.

Now, to determine the molar concentration of each ion in the solution, you need to consider the stoichiometry of CaCl2. Since CaCl2 contains one calcium ion (Ca2+) and two chloride ions (2Cl-), the molar concentration of each ion can be determined.

The molar concentration of calcium ions (Ca2+) will be the same as the molarity of the CaCl2 solution:

Molar concentration of Ca2+ = 0.0406 M

The molar concentration of chloride ions (Cl-) can be calculated by multiplying the molarity of CaCl2 by the stoichiometric coefficient of chloride ions:

Molar concentration of Cl- = stoichiometry coefficient × molarity of CaCl2

In this case, the stoichiometric coefficient of Cl- is 2 (from the formula CaCl2). Therefore:

Molar concentration of Cl- = 2 × 0.0406 M
= 0.0812 M

So, the concentration of calcium ions (Ca2+) is 0.0406 M, and the concentration of chloride ions (Cl-) is 0.0812 M in the solution.