1) Consider the following questions about acids and bases.

a) Note for each compound if it is

i) An acid or a base

ii) Weak or Strong

HF:

HCl:

NaCl:

Ca(OH)₂:

b) Predict the product of the following reaction. Make sure the reaction is balanced.

______H₂SO₄(aq)+______NaOH(aq)→

c) Write a net ionic equation for b).

d) Identify the acid and the base in the following reaction (remember the Bronsted Lowry definition).

CH₃COOH+NH₃→CH₃COO⁻+NH₄⁺

Project 7:   Acids and Bases

A neutralization reaction depends on the transfer of a proton, hydrogen, from one substance to another. The substance that donates the proton is an acid. That which accepts the proton is a base. pH is a measure of the molar concentration of hydrogen ion in a solution. The strength of an acid is determined by its ionization potential, or the relative amount of the hydrogen ion present in a compound that can be donated. If an acid can donate most of its hydrogen and become completely, or almost completely, ionized then it is a strong acid. Strong acids have a low pH, in the 1 – 2 range. A small potential proton donation results in a weak acid and the pH will be in the 3 – 6 range. A neutral solution, one in which the molar concentrations of hydrogen and hydroxide are equal, has a pH of 7. A predominance of free hydroxide ion in a solution indicates a base. A weak base has a pH of 8 – 11 and a strong base has a pH in the range of 12 – 14.

In order to test the hydrogen ion concentration of a solution, it is often convenient to use a substance that will change color as a result of the ion being present. Such a material is called a chemical indicator. In this experiment you will use an indicator made from red cabbage. Red cabbage works because it contains a water-soluble pigment called anthocyanin that changes color when it is mixed with an acid or a base. The pigment turns red in acidic environments and bluish green in alkaline (basic) environments. The following table shows the color corresponding to approximate pH ranges.

Procedure:

1. Tear, or cut, cabbage leaves into fairly small pieces and place them in a glass bowl.

2. Pour boiling water over the leaves to cover them completely, then let sit until the liquid is a purplish color and the solution has cooled. Remove the leaves by filtration or decantation saving the juice.

3. Pour approximately 2 Tablespoons of cabbage water into each of eight small colorless containers. Place thecontainers on plain white paper. Set one cup aside as your standard.

4. To each of the other seven containers, add a few drops of your testing solutions. Suggestions for testing solutions include, but are not limited to, lemon juice, vinegar, apple juice, baking soda, shampoo (preferably clear), conditioner (preferably clear), hand sanitizer, ammonia, laundry soap, cream of tartar and orange juice. When testing a solid material, dissolve it in water and then add a few drops of the resulting solution to a container of indicator.

Results:

1. Write the name of the solution that you tested in the appropriate box of a table.   

2. If you dilute your test solution with water before adding it to the indicator does it change the pH? Why, or why not?

3. In terms of an acid base reaction, why is Alka-Seltzer used to treat stomach aches?

4. What is acid rain and how is it a problem to oceans and rivers? (A one paragraph answer is sufficient.)

5. Include a labeled picture of your experimental results.

pH and pOH of strong acids, strong base, and neutral salts

a. What is the pOH of a 0.15 M solution of HBr(aq) at 25 oC?

b. A scientist prepares a solution by adding 300 mL of 0.03 M HCl to 500 mL of 0.02 M HClO4.

c. What is the pH of the resultant solutions at 25 °C. Assume that the volumes of the solutions are additive.

d. What is the pH of a 1.3 x 10–3 M sodium hydroxide aqueous solution at 25 oC?

e. At the same temperature, will the pH of a 0.01 M calcium hydroxide aqueous solution be the same, larger, or smaller than that of a 0.01 M NaOH(aq)?

f. Determine how the pH of the following three solutions will change when 100 mL of H2O is added separately to each of them.

g. 100 mL of 0.02 M KCl(aq) II. 100 mL of 0.02 M HCl(aq) III. 100 mL of 0.02 M KOH(aq)

Do the acids follow the same pH trend as their starting concentrations are changed? For example, if they followed the same trend we would expect the two sets of data points to lie parallel to one another. Is this is what is observed? Why do they or don’t they follow the same trend?

Background:

We plotted pH vs. -log[HA] on a graph using data from nitric acid and acetic acid. After plotting, the pH trends seem to be parallel to each other. We know that Nitric acid is a strong acid and acetic acid is a weak acid.

Write the dissociation reaction and the corresponding K_a equilibrium expression for each of the following acids in water. (For the dissociation reaction, include states-of-matter under the given conditions in your answer. Use the lowest possible whole number coefficients. Concentration equilibrium expressions take the general form: K_c = [HCl]² / [H₂] . [Cl₂].)

(a)    HC₅H₉O₂(aq)
dissociation reaction:

equilibrium expression:

(b)    Cr(H₂O)₆³⁺
dissociation reaction:

equilibrium expression:

(c)    C₃H₇NH₃⁺
dissociation reaction:

equilibrium expression:

Complete this paragraph with the words and phrases that follow. All acids have certain properties in common. When dissolved in water they produce a _______ taste, they turn _______ from blue to red, and they react with metals such as iron and_______ to liberate . Water solutions of bases, on the other hand, taste______ , turn litmus from _______ to ________ , and produce a _______ sensation when rubbed between the fingers. As long as we are dealing with water solutions of these substances, we can use the_____ definition of an acid and a base, which states that an acid is any substance that releases______ , while a base is any substance that releases _________ . The_______ definition eliminates the need for water in the definition by defining acid-base reactions in terms of a______ from an acid to base, regardless of solvent. Arrhenius Lewis proton transfer hydronium litmus red bitter pH less sour hydroxide ions zinc blue proton Bronsted electron pair greater slippery hydrogen gas smaller hydrogen ions

2a. Which of these substances is not found in the cell membrane?

1. fatty acids
2. chitin
3. cholesterol
4. phospholipids

2b. In the past meat was preserved by coating it with salt. One reason that this worked was that the salt, with a little bit of water, is __________relative to bacteria, and water would move _________ the bacteria killing them (hint: think beef jerky!!!!).

1. hypertonic; into
2. hypotonic; into
3. hypertonic; out of
4. hypotonic; out of

2c. Solution A 10% salt, is compared to Solution B, 5% salt. Solution A is

1. hypo-osmotic
2. isotonic
3. hypotonic
4. hypertonic

2e. Food coloring added to a container of water will eventually become evenly distributed even without stirring due to

1. diffusion
2. active transport
3. exocytosis
4. facilitated diffusion

5. 2f.A hypertonic solution as compared to a hypotonic solution under the same conditions has
   1. more, dissolved solutes
   2. the same number of water molecules
   3. a higher hydrostatic pressure
   4. a higher water potential

6. 2g.Movement of individual dye molecules as they are distributed throughout a tank of water
   1. is a random process
   2. results in the accumulation of dye molecules at one end of the tank
   3. is always against the concentration gradient
   4. results from differences in gravity, pressure, or both

1. Electrons extracted from fatty acids in the peroxisomes are transferred to __________________.

A. NAD+

B. molecular oxygen

C. cytochrome C

D. Quinones

2. Which of the following is a lipid-soluble electron carrier?

A. cytochrome C

B. FAD

C. NAD+

D. ubiquinone

3. Leptin predominantly signals through the:

A. JAK-STATS pathway

B. Metabolite Receptor Pathway

C. Receptor Tyrosine Kinase Pathway

D. GPCR Pathway

The table of diprotic acids below shows how the acidity of the 1st proton is always much higher than the acidity of the second proton.Thus, the pH of the solution is dominated by the equilibrium for the loss of the 1st proton.

What is the pH for a 1.12 M solution of Li2S?

52. Catabolism of fatty acids stimulates gluconeogenesis in all of the following ways EXCEPT:

1. By contributing to the production of NADH
2. By providing carbons for the glucose skeleton
3. By activating pyruvate carboxylase
4. By contributing to the production of ATP
5. By producing Acetyl-CoA

55. [NADPH/NADP+] is maintained at a high level in cells primarily by:

1. Lactate dehydrogenase
2. The combined actions of glucose -6 phosphate dehydrogenase and gluconolactonase
3. The action of the electron transport chain
4. Shuttle mechanisms as the α-glycerophosphate dehydrogenase shuttle
5. The combined actions of transketolase and transaldolase

56. If a cell requires more ribose-5-phosphate than NADPH:

1. Only the first phase of the pentose phosphate pathway would occur
2. Glycolytic intermediates would flow into the reversible phase of the pentose phosphate pathway
3. There would be sugar interconversions but no net release of carbons from glucose-6- phosphate
4. The equivalent of the carbon atoms to glucose-6-phosphate would be released as 6CO₂
5. Only part of this need could be met by the pentose pathway and the rest would have to be supplied by another pathway.