Answer :
Final answer:
To dilute a 78.2 ng/l solution to 2 ng/l, add sufficient solvent to achieve a final volume of 39.1 liters. This can be calculated using the dilution equation C1V1 = C2V2. So, the best option is b, Dilute the solution to 39.1 ng/l.
Explanation:
To make a 2 ng/l solution from a 78.2 ng/l starting concentration, you will need to dilute the starting solution.
The process involves adding more solvent to decrease the concentration of solute in the solution.
The specific calculation of how much solvent to add can be determined using the dilution equation:
C1V1 = C2V2
Where:
C1 is the initial concentration
V1 is the initial volume
C2 is the final concentration
V2 is the final volume
In this case, C1 is 78.2 ng/l, and C2 is 2 ng/l. To find V2, we rearrange the equation:
V2 = (C1V1)/C2
Assuming you start with 1 liter of the initial solution, we substitute:
V2 = (78.2 ng/l * 1 l) / 2 ng/l = 39.1 l
So, by adding enough solvent to reach a total volume of 39.1 liters, you can achieve a concentration of 2 ng/l. Answer B (Dilute the solution to 39.1 ng/l) is the correct choice for reaching the desired final concentration.
So, the best option is b, Dilute the solution to 39.1 ng/l.
