Question

Buffer Solution Question

Answer 1

A buffer solution is prepared by mixing 58.4 mL of 0.0846 M sodium dihydrogen citrate with 45.2 mL of 0.191 M sodium hydrogen citrate.
a) Calculate the pH of this solution.
- Found that pH to be 5.01

Now it asks:
Calculate the pH of the buffer solution after the addition of 0.0343 g of sodium hydrogen citrate (Na2C3H5O(COOH)(COO)2) to the buffer solution above

*Assume 5% approximation is valid and that the volume of solution does not change

Answer 2

you're essentially adding it up the 2 amounts.
So, convert 0.0343 g of sodium hydrogen citrate to moles, also convert 0.191 M sodium hydrogen citrate to moles (you know the volume).

Add the moles together and find the new concentration. Plug it into the HH equation.

Answer 3

so basically to get the sodium hydrogen citrate to be in moles I could just use the mass and divide it by its molar mass ? as to the sodium hydrogen citrate multiply it by the original volume to get 8.6332x10^-3 moles . then add those values together to get my mole value . Divide that by my original volume and input it back into my equation .

Answer 4

@aaronq

Answer 5

yeah. but use the total volume of the buffer when you find the new concentration

Answer 6

Alright i got it thanks ^.^

Answer 7

good stuff. no problem