Final answer:
To prepare a 0.25 M solution of Cobalt Nitrite in 450.00 mL, calculate the moles required, determine the mass of Cobalt Nitrite needed using its molar mass, dissolve this mass in water, and adjust the volume to 450.00 mL.
Step-by-step explanation:
To make a 0.25 M solution of Cobalt Nitrite with a volume of 450.00 mL, we must first calculate the number of moles of solute needed using the formula:
Molarity (M) = moles of solute / liters of solution
Therefore, moles of Cobalt Nitrite = Molarity × volume in liters.
This gives us: 0.25 M × 0.450 L = 0.1125 moles of Cobalt Nitrite.
Next, find the molar mass of Cobalt Nitrite (Co(NO₂)2) by adding the atomic masses of cobalt, nitrogen, and oxygen. Assuming the formula for Cobalt Nitrite is Co(NO₂)2, the molar mass can be calculated as:
(Co) + 2 × (N + 2 × O)
Once the molar mass is found, multiply it by the moles to find the mass of Cobalt Nitrite needed:
Mass of Cobalt Nitrite = molar mass × moles
Finally, use this mass to weigh out the solid compound and dissolve it in a volumetric flask, then add enough water to make the total volume up to 450.00 mL.
Stir or shake until the solid is completely dissolved.