Final answer:
To find the number of moles of CoCl3, first calculate the total mass of the solution from its volume and density. Then determine the mass of CoCl3 using its mass percentage and divide by the molar mass to get the moles.
Step-by-step explanation:
To calculate the number of moles of CoCl3 in the given solution, we must first determine the mass of CoCl3 in the solution using its density and the volume provided. Then, we use the percentage concentration to find the mass of the solute (CoCl3).
The mass of the solution can be calculated as follows:
Density × Volume = 1.206 g/mL × 172.6 mL = 208.2796 g
Now, we find the mass of CoCl3 using the mass percentage:
Mass of CoCl3 = 19.6% of 208.2796 g
19.6/100 × 208.2796 g ≈ 40.8215 g
To find the moles of CoCl3, we divide the mass by its molar mass. The molar mass of CoCl3 (assuming an approximation as it is not provided) is approximately 165 g/mol (computed from Co = 58.9 g/mol, Cl = 35.5 g/mol, so CoCl3 ≈ 58.9 + 3×35.5 ≈ 165 g/mol).
Moles of CoCl3 = Mass of CoCl3 / Molar mass of CoCl3
Moles of CoCl3 = 40.8215 g / 165 g/mol ≈ 0.2474 moles