Preparing buffers for pH testing - (Jul/23/2015 )

Hi,

I need to prepare some buffers, namely HCl and NaOH. I  want to prepare them at concentrations higher than 0.1M. The NaOH i have is just in pellet form and does not have a concentration or anything.  The HCl is in liquid form and is 0.1 M.   My question is can i use this 0.1M HCl to make    0.3 M HCl ?  i need about 1 litre. And also the NaOH, how much will i have to add to make 0.3 M solution (1 litre)?

Please help

grams NaOH:

m = M * c * V

mass (g) = molar mass (39.99 g/mole) * concentration (0.3 moles/L) * volume (1 L)

m= 11.99 grams (or better 12 g because the NaOH pellets are quite hygroscopic and it won't be that exact anyway (and be not too slow with weighing).

You cannot make an "undilution",i.e. you cannot concentrate a solution out of a more diluted one (except you invest in equipment and efforts which is compared to getting a more concentrated solution, useless, and with HCl almost impossible).

And finally, for me these are an acid and a base and not buffers.

hobglobin on Thu Jul 23 18:06:04 2015 said:

grams NaOH:

m = M * c * V

mass (g) = molar mass (39.99 g/mole) * concentration (0.3 moles/L) * volume (1 L)

 

m= 11.99 grams (or better 12 g because the NaOH pellets are quite hygroscopic and it won't be that exact anyway (and be not too slow with weighing).

 

You cannot make an "undilution",i.e. you cannot concentrate a solution out of a more diluted one (except you invest in equipment and efforts which is compared to getting a more concentrated solution, useless, and with HCl almost impossible).

 

And finally, for me these are an acid and a base and not buffers.

 

Thank you for explaining that formula so well.  I am just worried about the HCl now,  this means I would have to obtain a a 0.3 M HCl solution then.