Explanation:
When working with dillutions we can use this formula:
Vc * Mc = Vd * Md
Vc = Vd * Md/Mc
Where Vc and Mc are the volume and molarity of the concentrated solution and Vd and Md are the volume and molarity of the dilluted solution. Using that formula we can find the volume of the concentrated solution that we will have to mix with water to get the dilluted solution.
Vc = ? Mc = 8.15 M Vd = 0.250 L Md = 0.175 M
Vc = Vd * Md/Mc
Vc = 0.250 L * 0.175 M/(8.15 M)
Vc = 0.00537 L
1000 mL = 1 L
Vc = 0.00537 L * 1000 mL/(1 L)
Vc = 5.37 mL
Answer: We have to take 5.37 mL from the concentrated solution.
