Emily Chittenden3/28/14

Introduction

Oh no! It looks as though I (your teacher) have come down with the flu! Unfortunately, your school administration could only scavenge a substitute who has only had one chemistry class – 35 years ago! You know that your teacher was going to review part 1 of past unit on acids and bases. The sub doesn’t even know the difference between the two!

It is obvious that you have to teach the class today. The sub has no idea what is going on, and the other students need the review for next week’s exam. From definitions of acids/bases to pH and buffers, what how do you help reinforce what you and your classmates have learned this week?

Task

First, you will have to review the basic definitions of acids and bases. Secondly, you will recall what the strengths of acids indicate and how to find how strong an acid is. Most importantly, you will relate acids and bases and be able to calculate numerical indicators of one based on information from another. You will also explore common household/everyday substances and their acidity/basicity.

Lastly, you will combine all these concepts and do a virtual titration and analyze the process.

Process

First, you need to review what acids and bases actually are. Go to Wikipedia and search for acids. Read about the characteristics and properties of acids and do the following:

1. Define acids. Include both Arrhenius and Bronsted-Lowry definitions. If you found any other definitions that helped you better understand acids, include these as well.

2. List 3 properties of acids.3. List 3 applications of acids.

Reviewing bases is next, but Wikipedia is less specific for bases. Go to Google and do a search on bases (you may have to search something like “characteristics of bases” or “about bases chemistry”). Do the following:

1. Define bases. Include both Arrhenius and Bronsted-Lowry definitions. If you found any other definitions that helped you better understand bases, include these as well.

2. List 3 properties of bases.3. List 3 applications of bases.

Now, recall that acids and bases have different strengths. Read what this acid and base info has to say about strengths of acids and bases. Do the following:

1. Define a strong acid. Define a weak acid.2. Define a strong base. Define a weak base.

Emily Chittenden3/28/14

Acids and bases aren’t just separate entities that have nothing to do with one another. Remember that you can make an acid out of a base and vice versa. Go to this conjugate acid/base pairs website and answer the following:

1. What does the word conjugate mean, in your own words?2. How does a conjugate base compare with its pair acid?3. What is the conjugate base of hydrochloric acid?4. The sulfate ion is the conjugate base of what acid?

Acid and base constants relate to one another in combination with the water ionization constant. Read about acid, base, and water constants before you do the following:

1. Calculate the equilibrium base constant for the dissociation of .1 M of acetic acid.2. Calculate the equilibrium acid constant of a base with a dissociation constant of 1.8x10-5.3. Explain the relationship among acid, base, and water constants, in your own words.

We can liken the relationships among constants to the relationships between pH and pOH. From the previous website and your prior knowledge, do the following:

1. Calculate the pH if the [OH-] is 5.0x10-5 M.2. A solution is created by adding water to a 2.3x10-4 moles of NaOH and 4.5x10-6 moles of HBo

until the final volume is 1L. Calculate the pH of this solution?

Sure, it is easy to understand pH of chemicals we see every day in chemistry. But what about substances we see or use every day? Go to this site and view the common substances it lists. Do a google search about each substance and its chemical compound. Then search for its pH (you may want to do several searches to ensure you have a correct value for pH).

1. Explain, in your own words, what specific chemical elements make each substance acidic or basic.

2. Play the game and rank the substances in order by pH.

Acids and bases, as you should recall, can be analyzed through titrations. Go do a virtual titration and do/answer the following:

1. What is the initial pH of the solution in the flask?2. What does the pH tell you about the solution we are beginning with?3. What ions are present in the flask initially4. Begin your titration.5. Add 5.00 mL of NaOH.6. Does the pH change?7. Explain what happens in the flask.8. Now add 15.00 mL of NaOH.9. What is the new pH?10. Explain what happens in the flask.

Emily Chittenden3/28/14

11. Add 10.00 mL more NaOH.12. What happens in the flask?13. What part of the titration are you now at?14. What is the total volume of solution in the flask now?15. At pH=7, what ions and molecules are present in the flask?16. Is the solution in the flask acidic, basic, or neutral?17. What is the pH at the equivalence point?18. Add 5.00 mL more of NaOH. What happens the the pH?19. Add 5.00 mL of NaOH again. What is the pH?20. What is the net ionic equation for this reaction?21. Given the molarity of the NaOH and the initial volume of the HCl, calculate the molarity of the

solution.

Now, here is a short, simple quiz for you. With all that you know and have reviewed, it should be a breeze!

Evaluation

The following rubric will be used to evaluate your grade for this WebQuest. Please ask me if you have any questions on the grading point scale or descriptions. I will be thorough in providing comments as to why you lost points.

25-19 points 18-13 points 12-7 points 6-0 points

Participation of and

Viewing of All Materials

Student clearly viewed and read all material. Student

has no answers that contradict what was

presented in the provided

information.

Student viewed and read most of

the material. Student has no answers that

contradict what was presented in

the provided information.

Student left out information that

was clearly presented in the

material (making it obvious that he or she didn’t read the

material in its entirety).

Student viewed and read some of

the material. Student has answers that

contradict the provided

information.

It is clear that student viewed and read little to none of

the material. Student has incomplete, incorrect, or

contradictory answers to questions.

Emily Chittenden3/28/14

Critical Thinking

Student has thorough, elaborated

explanations for all non-numerical answers. Student

has used his or her own

words/thoughts in answers.

Student has somewhat thorough, somewhat elaborated

explanations for all or most non-

numerical answers. Student has used mostly his or her own

words/thoughts in all or most answers.

Student has incomplete, brief explanations for all or most non-

numerical answers. Student rarely uses his or

her own words/thoughts in

all or most answers.

Student has incomplete, incorrect, or

unelaborated explanations for

all non-numerical answers. Student

does not use his or her own

words/thoughts in any answers.

Mathematical Calculations

Student has shown all his/her own work, with

detailed steps and proper units.

Student has few to no calculation

errors.

Student has shown proper

formulas, equations, or

starting points. Student has

shown most of his or her work they did to get to the answer. Student

has some calculation errors.

Student has shown little work

or few steps. Student has incorrect or

improper formulas as starting points. Student has many calculation errors.

Student has shown no work on

all or most calculation

problems. Starting equations or

formulas are not specified on all or most problems.

Student has many calculation errors and/or incorrect

answers.

General

Student showed clear collaboration

with peers, especially inside group. Student

asked questions to peers and to me when needed.

Student showed some

collaboration with peers. Student

asked some questions when

needed.

Student showed some

collaboration with peers.

OR

Student asked some questions when needed.

Student neither showed

collaboration with peers NOR asked questions when needed. Student has incomplete

work.

Emily Chittenden3/28/14

Conclusion

Congratulations! Now you have successfully attained all the information and activities you need to teach the class today! You can tell the substitute that you got this. Guide your classmates and encourage communication!