Scoring Scheme: 3-3-2-1 Part II. You considered the properties of two acid-base indicators, phenolphthalein and methyl orange. Many indicators are weak acids in water and establish the equilibrium: HIn(aq)(Color 1) H2O(l) H3O (aq) In-(aq)(Color 2). Indicators change color depending on whether they are in a protonated (HIn) or unprotonated (In-) form. What is the equilibrium expression for the phenolphthalein indicator in water and what colors are the protonated and unprotonated forms of the indicator

Explanation:

Phenolphthalein is a protonated indicator and methyl orange is a basic indicator having hydroxyl ionisable part .

Phenolphthalein can be represented by the following formula

HPh  which ionizes in water as follows

       HPh        + H₂O      ⇄    H₃O⁺      +        Ph⁻

( colourless  )                    ( pink  )

In acidic solution it is in the form of protonated Hph form which is colourless

In basic medium , it ionises to give H₃O⁺ and unprotonated  Ph⁻ whose colour is pink .

aquifers are bounded above and below by impermeable rock. the driving force of groundwater movement in confined aquifers is pressure, rather than gravity.

in the analysis of systems that involve fluid flow, we frequently encounter the combination of properties u and pv.