I do not know how to solve this problem. Could you show me how?
You have a stock solution of 5.00M H3PO4.
a.) What would be the concentration if 20.0mL of the stock solution is diluted to 250.0mL?
b.) What volume of the dilute solution would you need if you needed 0.0200mol oh H3PO4?
I do these this way. You start with 5.00M and you dilute 20 mL to 250. You know the solution will be more dilute; therefore,
5.00 x (20/250) = 0.400 M
Another way is to say what is the dilution; it is 20/250 = 1 in 0.08 so the final concn must be 5.00 x 0.08 = 0.400.
Finally, if you're never sure what to do you plug into a formula.
c1v1 = c2v2
c = concn
v = volume
5.00M*20mL = c*250
c = 5*20/250 = 0.400M
Sure! Let's solve each part of the problem step by step.
a.) To find the concentration after dilution, we can use the formula:
C1V1 = C2V2
Where:
C1 = initial concentration of the stock solution
V1 = initial volume of the stock solution
C2 = final concentration of the diluted solution
V2 = final volume of the diluted solution
Given:
C1 = 5.00 M
V1 = 20.0 mL
C2 = ?
V2 = 250.0 mL
Substituting the given values into the formula:
(5.00 M) (20.0 mL) = C2 (250.0 mL)
Now, we can solve for C2:
C2 = (5.00 M * 20.0 mL) / 250.0 mL
C2 = 0.4 M
Therefore, the concentration of the diluted solution is 0.4 M.
b.) To find the volume of the dilute solution needed, we can rearrange the formula from part a:
C1V1 = C2V2
And solve for V2:
V2 = (C1 * V1) / C2
Given:
C1 = 5.00 M
V1 = ?
C2 = 0.4 M
V2 = 0.0200 mol
Substituting the given values into the formula:
V2 = (5.00 M * V1) / 0.4 M
Now, let's solve for V1:
V1 = (0.0200 mol * 0.4 M) / 5.00 M
V1 = 0.0016 L
Since we want the final volume in milliliters, we can convert 0.0016 L to mL:
0.0016 L * 1000 mL/L = 1.6 mL
Therefore, you would need 1.6 mL of the dilute solution to obtain 0.0200 mol of H3PO4.