Question

Need help understading the results of this lab that's about equilibrium and Le Chatelier's principle

System IV Acetic acid with bromocresol green indicator 1. Place about 10 drops of 0.1M HCl solution into a well and add one drop of bromocresol green to the well. Save as a color reference. 2. Place about 10 drops of 0.1M NaOH solution into a different well and add one drop of bromocresol green to the well. Save as a color reference. 3. Place about 10-15 drops of 1M acetic acid (CH3COOH) and one drop of bromocresol green indicator into each of three clean wells. One of the wells will serve as a color reference. 4. Add about a spatula tip full of solid sodium acetate (CH3COONa) to one of the wells containing acetic acid and bromocresol green. If no change occurs, continuing adding in very small increments until a change occurs. 5. Add one drop of 0.1M NaOH solution to another well with acetic acid and bromocresol green solution. Continue adding NaOH dropwise until a change occurs or until the well fills. If the well fills first, transfer the contents of the well using a dropper to a small beaker and continue adding 0.1M NaOH solution until no further change occurs (but do not add more than 10 mL of NaOH). Report For each system, explain each of the observed changes in terms of LeChatelier's Principle. Include the balanced equation for the reaction at equilibrium. For system I, include "heat" as a reactant or product in the equation for the reaction. Indicate if your prediction was supported by experimental evidence.

Reaults:

(#4) The addition of solid sodium acetate:

turned the solution green

(#5) The addition of NaOH:

turned the solution blue

Answer 1

Bromocresol green OH Br Br 8 B Er wu HO/ O +H* Bry Acidic form (Acidic solution) - Yellow color L Basic form (Basic solution) - Blue color Acidic form can indicated by InH and basic form In 1 HCl and bromocresol are there. So, equilibrium in acidic solution favors the formation of Hin and gives yellow color 2 NaOH and bromocresol are there. So, equilibrium in basic solution favors the formation of In and gives blue color 3 Acetic acid and bromocresol are there. So, equilibrium in acidic solution favors the formation of Hin and gives yellow color 4 Acetic acid and bromocresol and CH3COONa are there, acetic acid anmd CH3COONa forms a acidic buffer which is not that much acidic as HCI. So, equilibrium in acidic solution favors the formation of Hin and gives green color which in between yellow and blue colors 5 Acetic acid and bromocresol are there, when base NaOH excess added it forms basic solution. So, equilibrium in basic solution favors the formation of In' and gives blue color.