Last modified: Sat 10/26/2013 01:01:10 pm
ACA

Oklahoma State University

It is OK to use your textbook or lecture notes from class, but if you can answers the questions without it that is OK too.

Answer all of the questions below. If you do not know an answer enter CNA. However, it will help me the most if you answer each question with your best intuition/idea about what would be a reasonable answer.

Do not press the RETURN or ENTER key while you are answering these questions. Your browser will interpret either the same as clicking on the Submit key.

Answer all of the questions below. If you do not know an answer enter CNA.


First Name:

Last Name:

Laboratory Section:

1. Explain why aqueous solutions of NaCl and NaNO3 each have a pH of 7.

2. Explain why aqueous solutions of NH4Cl and NH4NO3 (that have the same initial concentration) each have the same pH.

3. Complete the following table

[H+]

[OH-]

pH

pOH

5.78 x 10-14 M

 

7.32 x 10-3 M

 

7.88

 

3.41

 

4. Predict whether the pH of 0.1 M solutions of each of the salts is greater, less or equal to 7.

Salt (0.1M)

pH (greater, equal or less than 7)

NaC4H7O2

(CH3)2NH2Cl


KCN

5. Write the Bronsted-Lowry equation which describes the acid/base character of the salts in Q4. (Hint: if you have indicated the salt has the properties of a base write a BL equation which supports that behavior.)

a) NaC4H7O2

b) (CH3)2NH2Cl

6. Calculate the pH for each of the following solutions;

a) 0.293 M NaC4H7O2 (Ka (HC4H7O2) = 1.5 x 10-5)

pH =

b) 0.634 M (CH3)2NH2Cl (Kb ((CH3)2NH) = 5.4 x 10-4)

pH =

6. In the pH meter simulation you are using for the Acid/Base Salt Activity click on the Unknown radio button and select Unknown6. Select a concentration and measure the pH of 100 mL of the solution. Enter the concentration of your unknown and its pH below.

[Unknown6] =

pH =

Based on pH measurement of your Unknown, the Acid/Base Salts Activity and this ACA what else do you know about the solution containing Unknown6 and about Unknown6 itself. Explain: (Note: this is an open-ended question.)

7. Is there anything about the questions that you feel you do not understand? List your concerns/questions.

8. If there is one question you would like to have answered in lecture, what would that question be?