Question

a. Do KOH and NaOH differ in measured pH? Why? Calculate the theoretical pH of these solutions.

b.How does the pH meter behave in tap and deionized water? Why does it act differently?

c. How well does the measured pH agree with the calculated value? What variables are responsible for observed discrepancies in measured and calculated pH?

Answer 1

a. The pH of NaOH and KOH is almost the same i.e. 10.9 however NaoH at times might show a higher pH value because of its greater solubility in molar concentrations.

b. pH of pure water is 7 but we never come across this in daily life. pH of tap water is slightly greater than 7 because of presence of alkali whereas pH of deionized water s slightly lower than 7(around 6.5) because it quickly reacts with carbon dioxide present in air to form carbonic acid

c. There are discrepancies in values of calculated and measured pH due to various factors like temperature, ionic strength of solutions, presence of CO_{2, unbuffered solutions etc.}