Final answer:
To dilute 20 mL of a 1.40 M solution of LiCN to a 0.0780 M solution, use the dilution formula (M1V1 = M2V2), which yields a final volume of approximately 358.97 mL after the dilution process.
Step-by-step explanation:
The student is asking how to dilute 20 mL of a 1.40 M solution of LiCN to make a 0.0780 M solution. To solve this problem, the concept of molarity and the conservation of moles in dilution must be used. We need to use the formula:
M1V1 = M2V2
Where M1 is the initial molarity, V1 is the initial volume, M2 is the final molarity, and V2 is the final volume. Let's use the above formula to calculate the final volume after dilution:
M1V1 = M2V2
1.40 M * 20 mL = 0.0780 M * V2
V2 = (1.40 M * 20 mL) / 0.0780 M
V2 = approx 358.97 mL
This is the final volume required to achieve a 0.0780 M solution when starting with 20 mL of a 1.40 M solution.