What are chemical indicators measuring? Explain what it has to do with acids and bases, thank you (:

Question

somy · Answer

Chemical indicators are used to find the end point of reactions. In case of acid base reactions indicators help to see when the reaction has ended by changing colour of the solution. Another thing we can also find is how much of the reactant is required for the reaction to take place. Again the indicator changes it's colour when the amount of the reactant is enough showing that reaction took place.

rajnie · Answer

Chemical Indicators are usually weak organic acids or bases. Their acidic form and the basic form have different colours.
$$HA \rightleftarrows H^+ + A^-$$In the above equilibrium of a weak acid HA, HA will have a colour and $A^- $ will have a different colour. When the concentration of HA is 10 times the concentration of $A^-$ the colour of HA will be predominant and when the concentration of $A^-$ is 10 times the concentration of HA the colour of $A^-$ will be predominant.

We can use this property to follow an acid-base titration.