Vernon B. answered 04/23/22
Experienced Scientist specializing in chemistry and mathematics
a) the weak acid with strong base is the red line. Weak acids will have a higher pH compared to strong acids when there is no base present. This means that the blue line is the strong acid with strong base
b) you will need an indicator that is near the equivalence point for this particular weak acid. The equivalence point occurs at around pH 9 (which is shown in the graph as a dramatic increase of pH indicating the equivalence point has been reached). Choose indicator with a pKa of 9.
c) The pKa of a weak acid can be determined by the graph. It is the y value of the graph at the half equivalence volume. This means that the pKa is around 6.
d) A weak base and its conjugate acid is a buffer which is known to control pH within a certain range. The weak base reacts with acid and the conjugate acid reacts with base to stabilize the pH.