Question

A sample of potassium hydrogen phthalate (KHC8H4O4), which is an acid, with a mass of 0.7292 g is dissolved in water and used to standardize a solution of cesium hydroxide. An endpoint is reached when 34.61 mL of cesium hydroxide has been added. Determine the molarity (in mol/L) of the cesium hydroxide solution. Report your answer to four significant figures.

Answer 1

the reaction taking place is:
KHP + CsOH ==> H2O + CsK2P2

molar mass of KHC8H4O4 = 204.44 g/mol
number of moles of KHC8H4O4 = mass / molar mass
                                                      = 0.7292/204.44
                                                       = 3.567 *10^-3 mol

number of moles of CsOH should equal number of moles of KHC8H4O4
number of moles of CsOH = 3.567 *10^-3 mol
number of moles of CsOH = 3.567 *10^-3
M*V = 3.567 *10^-3
M*0.03461 L = 3.567 *10^-3
M= 0.1031 M
Answer: 0.1031 M