How to make up pH or buffer solutions

[Cuishie]

My HOD is wanting to do the experiment "Membranes under stress" out of Heinemann Biol 2 Activity manual with beetroot slices and various solutions and the effect they have on the beetroot. I am unable to find how to make up the pH solutions and the teachers resource book tells me to look up the old "Web of Life Teachers Guide Part 2" for recipes, which I don't have a copy of. We only do the experiment once a year and usually only have one or two groups doing it so I don't want to buy buffer solutions etc that could go off before we are able to use them up.Any help would be greatly appreciated.
Cuishie

[kimmy]

Here is a copy of how we do our ph hope this helps

Making PH Solutions

To Make 200ml of each solution

To make a 200ml solution of PH1 to PH7
PH1 = .1 mol HCL 220ml (Base Solution)
PH2 = 20 ml .1 mol HCL + 180ml distilled Water = 200ml PH2
PH3 = 20 ml PH2 Solution + 180ml distilled Water =200ml PH3
PH4 = 20 ml PH3 Solution + 180ml distilled Water = 200ml PH4
PH5 = 20 ml PH4 Solution + 180ml distilled Water =200ml PH5
PH6 = 20 ml PH5 Solution + 180ml distilled Water = 200ml PH6
PH7 = Distilled water should have a PH of 7

To make a 200ml solution of PH14 to PH8
PH14 = 1.0 mol NaOH 220ml (Base Solution)
PH13 = 20ml NaOH + 180ml Distilled Water = 200ml PH13
PH12 = 20ml PH13 + 180ml Distilled Water = 200ml PH12
PH11 = 20ml PH12 + 180ml Distilled Water = 200ml PH11
PH10 = 20ml PH11 + 180ml Distilled Water = 200ml PH10
PH9 = 20ml PH10 + 180ml Distilled Water = 200ml PH9
PH8 = 20ml PH9 + 180ml Distilled Water = 200ml PH8
PH7 = Distilled water should have a PH of 7

[rae]

Kimmy

What do you make these solutions up in?? Volumetric flasks or measuring cylinders??
If you are doing serial dilutions like this what happens to the accuracy or doesn't it matter??

Lorrae

[Marjan]

Kimmy

What do you make these solutions up in?? Volumetric flasks or measuring cylinders??
If you are doing serial dilutions like this what happens to the accuracy or doesn't it matter??

Lorrae

Hi Lorrae
To get the most accurate results you should use volumetric flasks as M.C.s aren't so.
Good luck
Marjan

[kimmy]

I use Volumetric flasks and to extract the 20ml from the previous pH I use a 20ml Pipette then transfer it to the volumetric flask.
Good luck

[Jazz]

Hi,
try this one

pH solutions

Standard pH solutions may be easily prepared using the following recipes:

pH2 0.01M hydrochloric acid
pH3 80mL 0.1M citric acid plus 20mL 0.2M disodium hydrogen phosphate
pH4 62mL 0.1M citric acid plus 38mL 0.2M disodium hydrogen phosphate
pH5 48mL 0.1M citric acid plus 52mL 0.2M disodium hydrogen phosphate
pH6 37mL 0.1M citric acid plus 63mL 0.2M disodium hydrogen phosphate
pH7 18mL 0.1M citric acid plus 82mL 0.2M disodium hydrogen phosphate
pH8 3mL 0.1M citric acid plus 97mL 0.2M disodium hydrogen phosphate
pH10 0.1M sodium hydroxide

These solutions are sufficiently accurate for use in the cell membrane activity in Biology and also for general pH testing

[Cuishie]

Thanks for all your help. This is a great website, keep up the good work!!!
Cuishie