Question

Consider a solution containing 0.100 M fluoride ion and 0.126 M hydrogen fluoride. The concentration of fluoride ion after addition of 5.00 mL of 0.0100 M HCl to 25.0 mL of this solution is ______M.

Answer 1

initially there's 2.5 x 10-3 mol fluoride ions (mol=Molarity x Volumeliters)

when u add 5 x 10-5 mol HCl, 5 x 10-5 mol of fluoride ions get used up

so left with 2.45 x 10-3 mol of fluoride ions

converting that to Molarity (mol/L) divide 2.45 x 10-3 by [(25+5) x 10-3 L]

and u get 0.08167 M

Answer 2

How did you get the 2.5X10-3?

Answer 3

5 ml of 0.0100M solution of HCl is added to the 25 ml of fluoride solution.