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19 Nov 2019
Generalized Weak Acid Equilibrium HA (aq) H2O()A (aq) + H30+ (aq) Aqueous Solution of HA And the Salt of its Conjugate Base (NaA) Aqueous Solution of HA One Source of A (from the HA equilibrium) Two Sources of A (from the HA equilibrium And from NaA) Solution 2 Contains the Common lon: A Solution 1 Solution 2 Since the additional conjugate base (added as the salt) is one of the products in the weak acid equilibrium, we can use Le Chatelier's principle to predict how this would change the composition of the overall equilibrium Imagine you have a 1.0 M solution of the weak acid, HA (like solution 1 in Figure 1). Given a Keq value we would be able to calculate all the equilibrium concentrations as well as the pH. If we then added some of the salt NaA, we would create the common ion effect. This solution (like solution 2 above) would now have more of conjugate base anion (A in this case) then we had in our original weak acid solution Using LeChatelier's principle to guide your reasoning, select all of the following changes you would expect for each of the following parameters as a result of adding this common ion O The pH of this solution would increase as the solution returned to equilibrium The concentration of [H3O+] would increase as the solution returned to equilibrium. The Keq Would increase as the solution returned to equilibrium The Keq Would decrease as the solution returned to equilibrium o After an initial rise from adding the salt, the [A] would decrease as the solution returned to equilibrium The [HA] would increase as the solution returned to equilibriunm
Generalized Weak Acid Equilibrium HA (aq) H2O()A (aq) + H30+ (aq) Aqueous Solution of HA And the Salt of its Conjugate Base (NaA) Aqueous Solution of HA One Source of A (from the HA equilibrium) Two Sources of A (from the HA equilibrium And from NaA) Solution 2 Contains the Common lon: A Solution 1 Solution 2 Since the additional conjugate base (added as the salt) is one of the products in the weak acid equilibrium, we can use Le Chatelier's principle to predict how this would change the composition of the overall equilibrium Imagine you have a 1.0 M solution of the weak acid, HA (like solution 1 in Figure 1). Given a Keq value we would be able to calculate all the equilibrium concentrations as well as the pH. If we then added some of the salt NaA, we would create the common ion effect. This solution (like solution 2 above) would now have more of conjugate base anion (A in this case) then we had in our original weak acid solution Using LeChatelier's principle to guide your reasoning, select all of the following changes you would expect for each of the following parameters as a result of adding this common ion O The pH of this solution would increase as the solution returned to equilibrium The concentration of [H3O+] would increase as the solution returned to equilibrium. The Keq Would increase as the solution returned to equilibrium The Keq Would decrease as the solution returned to equilibrium o After an initial rise from adding the salt, the [A] would decrease as the solution returned to equilibrium The [HA] would increase as the solution returned to equilibriunm
Patrina SchowalterLv2
5 Feb 2019