[firecard]

I am glad to find this forum.

I have a problem here. I need to make a solution of x gram of NaCl, y gram KCl and z gram NaHCO₃ into say 1 litre of RO water.

x and y are known figure, as I need to get them into right concentration.

And I need the end result to be in pH of 6.5 with varying the weight of NaHCO₃ of z gram.

Can some help me with the calculation?



I need to apologise if this is not the correct sub forum to post, mod please move it to the correct one.

[wpenrose]

For one liter solution, add your NaCl, KCl to 800 mL water and dissolve. Put in a pH electrode and add 0.01 M NaHCO2 until the pH is 6.5. Make to one liter and touch up the pH with more NaHCO3 if needed. Seal the solution from the air.

In this range, theoretical calculations will be useless. You're at the first pKa of carbonic acid, so the amount you add will depend on how much CO2 is dissolved in the solution.

Dangerous Bill

[AWK]

I am glad to find this forum.

I have a problem here. I need to make a solution of x gram of NaCl, y gram KCl and z gram NaHCO₃ into say 1 litre of RO water.

x and y are known figure, as I need to get them into right concentration.

And I need the end result to be in pH of 6.5 with varying the weight of NaHCO₃ of z gram.

Can some help me with the calculation?



I need to apologise if this is not the correct sub forum to post, mod please move it to the correct one.

THis problem is unsolvable at room temperatute. pH of NaHCO3 is close to 8. Ionic strentgth below 1 M decreases pH slightly  up to 0.15 pH unit.

[wpenrose]

What about the dissolved CO2 that will make the initial pH in the 4.5 to 6 range?

DB

[AWK]

What about the dissolved CO2 that will make the initial pH in the 4.5 to 6 range?

DB

You pointed out in you previous post that

theoretical calculations will be useless

since for calculations a concentrations of H₂CO₃ or CO₂ over solution are needed.
Of course, bicarbonate/CO₂ buffer can give pH around 6.5 but probably you need at least 1 atm presssure of carbon dioxide