20 mL of an approximately 10% aqueous solution of
ethylamine, CH3CH2NH2, is titrated with 0.3000 M
aqueous HCl. Which indicator would be most suitable
for this titration? The pKa of CH3CH2NH3
+ is 10.75.

(A) Thymol blue, color change from pH = 1.2 to 2.8
(B) Bromocresol green, color change from pH = 4.0 to
5.6
(C) Phenolphthalein, color change from pH = 8.0 to 10.0
(D) Alizarin yellow R, color change from pH = 10.0 to
12.0

adding or remove a gaseous reactant or product changes the concentrations. if the concentration of reactant or product is increased, the system will shift away from the side in which concentration was increased (i.e. if the concentration of reactants is increased, the system will shift toward the products. if more products are added, the system will shift to form more reactants). conversely, if the concentration of reactant or product is decreased, the system will shift toward the side in which concentration was decreased (i.e. if reactants are removed, the system will shift to form more reactants. if the concentration of products is decreased, the equilibrium will shift toward the products).

explanation: