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
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?
1 answer