Question

DATE: TEAM MEMBERS SECTION TA: Ch atelier's Principle: Chemical Equilibrium and Determination Equilibrium Constant ST-LABORATORY QUESTION 1. For the following reaction: 2 H30' (aq)-Cr,072-(aq) + 3 H20 (r) 2 Crof (a) yellow + orange Use Le Chatelier's Principle to account for the effect of adding H,SO, to a solution of K,Cro, (1.5 pts) a. b. Use Le Chatelier's Principle to account for the effect of adding when NaOH to the mixture in question la. (1.5 pts) 7 Far the following reaction:

Answer 1

First, let us state the Le Chatelier principle which deals with changes in an equilibrium:

The statement is as follows:

If any equilibrium is disturbed, that is, change in conditions such as P,T, concentration, partial pressure, etc.., the system will counterbalance such change in order to favour the system's equilbirium.

• Change in concentration
• Change in pressure
• Change in temperature

a.

if we add H2SO4, H+ increases in solution, that is H3O+.

this is a reactant, will form crO7-2 and 3H2O, therefore, the orange will be seen in stronger concentration/color than yellow

b.

if we add NAOH = OH- ions, then

H3O+ + OH- = H2O

then, H2O increases, H3O+ decreases

this favours towarrs CrO4-2, which is yellow