Determine the best buffer and be able to defend your choice.
The measurement of hydrogen ion concentration is called pH. Around the value of zero you have a strong acid or an acid that produces lots of hydrogen or H+ ions. At pH 7 the solution has equal amounts of acidic and basic ions and is called neutral. Pure water is pH 7 because it has equal amounts of H+ and hydroxide or OH- ions. Buffers work against a change in pH until overcome by too many ions.
Use a universal indicator or electronic pH measurement device to determine when the pH has changed 2.5 units.
The following buffer formulas may help you in determining reactions.
Chemical Name Formula Molecular Weight
Hydrochloric acid HCl 36.47
Potassium chloride KCl 74.55
Potassium phosphate (monobasic) KH2PO4 136.09
Potassium phosphate (dibasic) K2HPO4 174.18
Sodium carbonate Na2CO3. 7 H2O 232.12
Sodium hydroxide NaOH 40.01
Sodium hydrogen carbonate NaHCO3 84.02
Sodium phosphate (tribasic) Na3PO4.12 H2O 380.16
The following buffer formulas may help you in determining reactions.
Chemical Name Formula Molecular Weight
Hydrochloric acid HCl 36.47
Potassium chloride KCl 74.55
Potassium phosphate (monobasic) KH2PO4 136.09
Potassium phosphate (dibasic) K2HPO4 174.18
Sodium carbonate Na2CO3. 7 H2O 232.12
Sodium hydroxide NaOH 40.01
Sodium hydrogen carbonate NaHCO3 84.02
Sodium phosphate (tribasic) Na3PO4.12 H2O 380.16
Chemical Name Formula Molecular Weight
