Part III: On Acid Sokka and Momo drank some yummy cactus juice but it upset their body a bit due to the acidity. Katara asked Aang to help her but when she needed him most he vanished. She has to settle for your help making a remedy for Sokka and Momo. 1) You take out your lab equipment and you have a series of solutions of acids and bases that can be used to offset the acid. They are labeled with their pH value. Katara needs you to explain to her what a pH value is and why you use pH instead of just hydrogen concentrations. (10 pts) 2) What equation does Katara need to use to determine Hydrogen concentration from pH? (5 pts) 3) If the concentration of protons in the cactus juice is equal to 10-4 M , what is the pH? (5 pts) 4) To cure Sokka and Momo you need to use a solution with a pH of 10. What is the concentration of protons in the remedy? (5pts) Part IV: The Big Four ¥ For each of the four images below identify: which type of macromolecule they represent, their subunits, the bonds that hold each subunit together, and their overall function. (5 pts/image)

2. The weak base, hydroxylamine (HONH2) is generally stable in solution but can easily explode if dried into its solid state. The pKa of its conjugate acid is 5.96 (Harris, Appendix G). A 50.0 mL solution containing hydroxylamine is titrated to the endpoint with 32.84 mL of 0.0568 M HCl.

a) Write out the chemical equation for the aqueous equilibrium of this aqueous monoprotic base before the addition of any acid. Also write out the also the mathematical equilibrium expression. What fraction of hydroylamine is dissociated into ions, initially?

b) Write the expression for the relevant equilibrium process occurring following complete neutralization (to the equivalence point) described above. What fraction of the conjugate acid is dissociated into ions at this point?

c) What acid/base indicator is best suited to the pH of this titration endpoint? Support your choice quantitatively, and use the textbook table of indicators in Chapter 10 of Harris 8th Edition of Quantitative Chemical Analysis.

d) Since this is the titration of a very weak base, identify a possible analytical approach you could use to improve the quantification of hydroxylamine; in other words, when the endpoint isn’t very clear, what is an example of a technique used to titrate very weak acids or bases?

1. write the balance chemical equation for the reaction of KHP with NaOH
2. Suppose your laboratory instructor inadvertently gave you a sample of KHP contaminated with NaCL to use in standardizing your NaOH. How would this affect the molarity you calculated for your NaOH solution? Justify your answer.
3.How many grams of NaOH are needed to prepare 500ml of 0.125 M NaOH?
4 A solution of malonic acid H2C3H2O4, was standardized by titration with 0.1000 M NaoH solution. If 20.76ml of the NaOH solution is required to neutralize completely 12.95ml of the malonic acid solution, what is the molarity of the malonic acid solution.
H2C3H2O4 +2NaOH > Na2 C3H2O4 + 2H2O
5. Sodium Carbonate is a reagent that may used to standardize acids in the same way you used KHP in this experiment. In such a standardization, it was found that a 0.512g sample of sodium carbonate requried 26.30ml of sulfuric acid solution to reach the end point for the reaction.
Na2CO3(aq) + H2SO4(aq)> H2O(l) + CO2 (g) + Na2SO4(aq)
What is the molarity of the H2SO4.
6. A solution contains 6.30 ×10-2g of oxalic acid H2 C2 O4. 2H2O, in 250ml. What is the molarity of this solution.

1. If the job of a plasma cell (a type of immune cell) is to make and secrete antibody proteins, which structure(s) might you find a lot of in these cells?

2. If your body tissues are made up of millions of microscopic cells, why don’t they all just fall apart like grains of sand?

3. Your heart needs a constant supply of energy. Which cellular structure might you find in abundance in heart cells?

4. There are special immune system cells called “macrophages” that travel around your body eating up bacteria and dead cells (“macro” means big, “phage” means eater, so a “macrophage” is literally a “big eater”). Which cellular structure(s) do you think these cells might have in abundance?

5. We know that organisms are made out of cells and that cells are made out of cellular structures. But what are cellular structures made out of? In the table below, check off which type(s) of biomolecules make up the major parts of different cellular structures

Which one of these is not like the others? (2 pts each) In each set of 3 molecules CROSS OUT one option that does not fit and indicate the correct explanation for why it does not fit the set in the blank. For each set cross out only ONE molecule, and if the same set occurs twice choose a different molecule each time, using a different answer for each blank.

1. a) Glycogen Amylose

   Amylopectin

2. b) Chitin

   Cellulose

   Amylopectin

3. c) Chitin

   Cellulose

   Amylopectin

4. d) Triacylglycerol

   Sphingolipid

   Glycerophospholipid

5. e) Triacylglycerol

   Sphingolipid

   Glycerophospholipid

6. f) Proteoglycan

   Glycoprotein Lectin

_______
_______
_______
_______
_______
_______

Explanations: (not all will be used)

1. Twohaveα1→4linkages;onehasβ1→4linkages

2. Twohaveβ1→4linkages;onehasα1→4linkages

3. Two have α1→6 linkages; one has β1→6 linkages

4. Twohaveα1→6branches,onedoesnot

5. TwodoNOThaveα1→6branches,onedoes

6. Two are made from D-glucose, one is not

7. Two are easily digestible by most animals, one is not

8. Two are used for energy storage, one is not

9. Two are made from glycerol, one is not

10. Two are made from fatty acids, one is not

11. Twoaremembranelipids,oneisnot

12. Two contain protein components, one does not

13. Two have covalently attached carbohydrates, one does not

Data Table 2. Reviewing Compounds.

Data Table 3. Benzene.

Data Table 4. Alcohols.

Data Table 5. Ethers, Aldehydes, and Ketones.

Data Table 6. Carboxylic Acids and Amines.

Questions

Describe the difference between an aldehyde and a ketone.

The experiment is Determination of Acetic Acid in Vinegar. Please answer as many questions as you can.

What are primary and secondary standards? Give examples.

What is KHP and why was it used in this lab?

How is acetic acid formed in vinegar solution?

Why are pH indicators strongly colored even in solid state?

Why/how do pH indicators change colors in acid-base solutions?

Molar mass of acetic acid is often calculated or experimentally measured as 120 g/mol. Why?

Suggest another analytical method to determine the end point of an acid-base titration.

pH indicators are often weak acids or bases. Would adding indicators interfere with the determination of the endpoint for desired acid-base titration?

If a solution of NaOH is prepared and standardized today and left on the bench for a week, would you expect the pH of the solution change? Why? Ignore solvent (water) evaporation.

You had titrated unknown vinegar solution in flask against standard NaOH from burette using phenolphthalein indicator. If you had titrated standard NaOH solution in flask against unknown vinegar solution in burette using the same indicator, would it be easier or more difficult? Why?

PLEASE CHECK MY ANSWERS!

(1 pt each) If the following generally apply to all prokaryotes, write ‘P’. If they apply specifically to eukaryotes, write ‘E”. If they apply primarily to bacteria, write ‘B’, and if they apply primarily to archaea, write ‘A’. If it applies to more than one, include letters it applies to. 1 point each.

___P____6. DNA is organized in usually one large, circular chromosome.

____E___7. Cells contain membrane-bound organelles.

____P&B___8. Cell walls are common and contain some amount of peptidoglycan

____B&A___9. Small, circular pieces of DNA called plasmids, which are easily transferred, can often be found in cells.

____E___10. Ribosomes are found in cells and the entire ribosome size is ‘80S’, based on sedimentation rate.

____B&E___11. Phospholipids that comprise cell membrane feature fatty acids that are linked to glycerol by ester linkages.

__A_____12. Cell walls consist of protein/glycoprotein layer called S layer, pseudomurein layer, or in rare cases, only a slime layer outside of membrane(s).

___B&A____13. Typical shapes include bacilli and cocci.

____E___14. Cells have a cell membrane, DNA, and ribosomes.

_____A__15. Reproduction is asexual, and cells do not undergo mitosis or meiosis.

Every weak acid has the following unique characteristic(s):

a. at the 50% titration point the pH = pKa

b. the best buffering occurs +/- one pH unit of the pKa

c. the change in pH with added acid or base is the least when pH = pKa

d. the shape of the titration curve is essentially the same for all weak acids

e. all of the above

If the pH of a buffer with a pKa of 6 changes from pH 6 to 7 how does the [A-]/[HA] ratio change:

a. from 1/10 to 1/1

b. from 10/1 to 1/1

c. from 1/1 to 1/10

d. from 1/1 to 10/1

e. from 1/10 to 10/15

If the hydrogen ion concentration of a solution is 10^-5 M, what is the hydroxyl ion concentration:

a. 10^-5

b. 10^-1

c. 10^-2

d. 10^-9

e. 10^-5

What is the pH of a buffer with a pKa of 5 when the ratio of [A-]/[HA] is 10/1:

a. 3

b. 4

c. 5

d. 6

e. 7

If the pH is 8 what is the pOH:

a. 8

b. 4

c. 6

d. 12

e. 1

A 25-year-old woman with type 1 diabetes comes to the emergency department complaining of thirst, frequent urination, and weakness. She feels “lightheaded” when she stands. Because of nausea and vomiting after a meal in a restaurant the previous day, she stopped eating and taking her insulin. On examination, she is dehydrated and hypotensive. Her breathing is rapid and deep. 1. Which of the following is likely to be lower than normal? a. Urinary urea levels b. Plasma levels of glucagon c. Plasma levels of free fatty acids d. Blood partial pressure of carbon dioxide e. Plasma acetoacetate levels 2. Which of the following will increase after insulin administration? a. Plasma triglyceride levels b. Plasma K+ levels c. Lipoprotein lipase activity d. Adipose tissue lipase activity e. Plasma phosphate levels For each question, please first clearly indicate which option (a, b, c, d or e) is correct and which one is wrong and then explain briefly your reasoning for each answer. For instance, you must write: "a" is a correct answer because .... "b" is a wrong answer because..... "c" is wrong because ..... :d" is wrong because ...... etc.b