Making pH 7 Buffers

Considering you have the necessary chemicals:

250mL of 0.100M Potassium Phosphate Monobasic KH2PO4 (3.4022g in ~250mL dH2O)

250mL of 0.100M Sodium Phosphate Dibasic Na2PO4 (6.7017g in ~250mL dH2O)

Mix in 500mL container, add colour key preservative if you have it.

Notes:
- Obviously, use proper lab techniques. Don't just measure out 250mL of water and mix. Pour the amount in a beaker, add roughly half of the volume of water, dissolve, then dilute to 250mL in a grad cylinder.
- Solutions must be of exact concentrations, use an analytical balance if you have it.
- Water should be freshly distilled (deionized too if you can), do not use old stock dH2O as it tends to be acidic and it may cause the pH to shift a little.