You make 500 mL of a solution of cobalt(II) nitrate with concentration 0.250 mol L−1. You dilute this solution to 800 mL. Which of the following statements about your diluted solution is correct?

To answer this question, we first need to calculate the number of moles of cobalt(II) nitrate in the original solution.

Step 1: Calculate the number of moles in the original solution The number of moles (n) can be calculated using the formula n = C*V, where C is the concentration and V is the volume.

In this case, C = 0.250 mol/L and V = 0.500 L (since 500 mL = 0.500 L), so n = 0.250 mol/L * 0.500 L = 0.125 mol.

Step 2: Calculate the concentration of the diluted solution The number of moles of cobalt(II) nitrate will remain the same after dilution, but the volume of the solution will increase.

The new volume is 800 mL = 0.800 L.

We can calculate the new concentration (C') using the formula C' = n/V'.

In this case, n = 0.125 mol and V' = 0.800 L, so C' = 0.125 mol / 0.800 L = 0.156 mol/L.

So, the correct statement about the diluted solution is that its concentration of cobalt(II) nitrate is 0.156 mol/L.