Question

A chemist wishes to make a solution using 4.21 g of CoCl3 in which the total concentration of Cl– ions is equal to 0.333 mol/L. What must the final volume of the solution be?

Let's start by understanding the relationship between [CoCl3] and [Cl–].
In order for [Cl–] to equal 0.333 M, what must [CoCl3] equal?
M
Molarity is defined as
$$moles soluteL solution​
, so we need to calculate the moles of CoCl3. How many moles of CoCl3 are equivalent to
4.21 g of CoCl3?
moles CoCl3
Finally we can calculate the final volume of the solution.
What final volume will produce a solution in which [Cl–] = 0.333 M, using 4.21 g of CoCl3?
L solution

Answer 1

To find the final volume of the solution, we need to determine the concentration of CoCl3. Using the given information, we can calculate the final volume to be 32.4 mL.

Step-by-step explanation:

To find the final volume of the solution, we need to determine the concentration of CoCl3. Since the concentration of Cl- ions is given as 0.333 mol/L, we can use the formula [CoCl3] = 3 x [Cl-] (because there are three Cl- ions in one CoCl3 molecule). Therefore, [CoCl3] = 0.333 x 3 = 0.999 mol/L.

Next, we need to calculate the number of moles of CoCl3. Using the formula moles = mass / molar mass, we have: moles = 4.21 g / (129.84 g/mol) = 0.0324 mol.

Finally, we can calculate the final volume using the formula: final volume = moles / [CoCl3] = 0.0324 mol / 0.999 mol/L = 0.0324 L = 32.4 mL.

Answer 2

To achieve a chloride ion concentration of 0.333 M using 4.21 g of CoCl3, the final volume of the solution should be approximately 0.2286 liters.

Step-by-step explanation:

To determine the final volume of the solution in which [Cl−] is equal to 0.333 M, we first need to calculate the amount of CoCl3 in moles. CoCl3 contains three chloride ions for each formula unit. Therefore, to achieve a chloride concentration of 0.333 M from CoCl3, the concentration of CoCl3 must be 0.111 M because each unit of CoCl3 dissociates into three Cl− ions.

Using the molar mass of CoCl3, which is roughly 165.87 g/mol, we can convert the mass of 4.21 g of CoCl3 to moles:

4.21 g CoCl3 × (1 mol / 165.87 g) = 0.02538 mol CoCl3

Since molarity (M) is defined as moles of solute per liter of solution, the final volume of the solution can be calculated using the molar concentration of CoCl3:

Volume = Moles of solute / Molarity of CoCl3

Volume = 0.02538 mol / 0.111 M = 0.2286 L

Therefore, the chemist must dissolve 4.21 g of CoCl3 in a final volume of approximately 0.2286 liters to achieve a chloride ion concentration of 0.333 M.