Question

1)A 0.500 M standard solution of NaOH cannot be made up by weighing out solid NaOH and dissolving it in the correct amount of water. thus NaOH cannot serve as a primary standard. suggest two reasons for this

2)suggest a reason why the normality of NaOH solutions may change if the solution is exposed to air for an extended period of time

3)why was phenolphthalein suitable as an indicator for this experiment? can yu suggest another indicator that might be suitable as well