

Study with the several resources on Docsity
Earn points by helping other students or get them with a premium plan
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Community
Ask the community for help and clear up your study doubts
Discover the best universities in your country according to Docsity users
Free resources
Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors
A problem set for morehouse college's chemistry 112 - elementary inorganic chemistry course. The problem set includes various chemistry-related questions, such as identifying the ph of a solution after dilution, determining which statements are true at equilibrium for a given reaction, calculating the poh of a solution, and identifying the reaction direction for a given reaction. The problem set also includes a question requiring students to write a balanced chemical equation and calculate the equilibrium constant for the reaction between mgo and water.
Typology: Assignments
1 / 2
This page cannot be seen from the preview
Don't miss anything!
DUE: Monday, February 25, 2008 in class
Answer all questions in the space provided, neatly written. Thanks.--BML
a. If 5.17 mL of 3.0 M NaOH(aq) is diluted to a final volume of 2.60 L, what is the pH of the resultant solution?
0.05 2.22 5.17 8.83 11.
b. Consider the following reaction:HCl(aq) + H 2 O(liq) H 3 O+(liq) + Cl-(aq) where Keq >>> 1. Which of the following statements are true at equilibrium?
H 2 O is a H 2 O is a Cl-^ is a HCl is a none of these stronger acid stronger acid stronger base stronger acid than HCl than H 3 O+^ H 2 O than H 3 O+
c. If 150 mg KOH(aq) are dissolved in water to give a final volume of 110 mL, what is the pOH of the resultant solution?
0.26 1.1 2.6 12.4 none of these
d. Consider the following reaction: CH 3 CO 2 H + NH 3 NH 4 +^ + CH 3 CO 2 - Which of the following statements is true?
K eq = 1 the reaction will the reaction will none of these favor product favor reactant formation formation
e. Suppose 50 mL of a 0.10 M solution of H 2 S(aq) is prepared. What will be the pH at equilibrium in this solution if the acid dissociation constant Keq = 1.0 x 10-7?
0.00 4.00 7.00 10.0 none of these
To begin, we write a balance chemical equation. Since O^2 - (aq) is the conjugate base of OH-(aq), a strong base, it would be likely that O2-(aq) will react completely with water in solution to generate two hydroxide ions. That is…
MgO(s) Mg2+(aq) + O2-(aq)
O2-(aq) + H 2 O(liq) 2OH-(aq)
Taken together, these reactions become...
MgO(s) + H 2 O(liq) Mg2+(aq) + 2OH-(aq)
Now that we have a chemical equation, we can take to the work of finding the equilibrium constant. First, we’ll write the expression for K eq for the last of the above equations…
[Mg ][OH] (Question:Whyisthedenominator"one?" ) 1
[Mg ][O ] [Reactants]
[Products] 2 +^2 - 2 + 2 Keq = = =
To solve for K , we need to find the concentrations of magnesium and hydroxide ions. Since the pH is given, we can first determine the [H+].
-pH -10.16 11 pH log 10 [H ] orequally[H ] 10 10 6.918x 10 =− + + = = = −
From the relationship between [H+], [OH-], and K w, we can determine [OH-]…
11 4 M
14 w
w
1.445x 6.218x 10
1.000x 10 [H ]
− −
−
−
To determine the concentration of Mg2+^ ions, we use the reaction stoichiometry…
MgO(s) + H 2 O(liq) Mg2+(aq) + 2OH-(aq)
From this relationship, we deduce that [Mg2+] = 0.5 [OH-] = 7.227 x 10-5^ M. This is also the solubility of MgO(s) in solution. Lastly, we can write an equilibrium expression for the production of ions in solution. This is just K eq for the same equation written above…
[Mg^2 ][OH]^2 (7.227x 10 -^5 )(1.445x 10 -^4 )^2 1.509x 1012 [Reactants]
[Products] (^) + − Keq = = = =