Which of the following buffer systems would be the best choice to create a buffer with pH = 9.00? HF/KF HNO2/KNO2 NH3/NH4Cl HClO/KClO

For the best system, calculate the ratio of the masses of the buffer components required to make the buffer. Express your answer using two significant figures.

Comparison of Fresh and Sour Milk

pH of fresh milk:

pH of sour milk:

Which type of milk has the lower pH?

The greater acidity?

The greater H+ concentration. What organic (carboxylic) acid produces the H+ in sour milk? What is its source?

(5)

Chloroacetic acid, HC₂H₂ClO₂, has a greater acid strength than acetic acid because the electronegative chlorine atom pulls electrons away from the O-H bond and thus weakens it. Calculate the hydronium ion concentration and the pH of a 2.49E-3 M solution of chloroacetic acid. K_a is 1.3E-3.

[H₃O⁺] = _____ M

pH = _____

Arsenic is a toxic metal that can be found in the water supply. Begin a discussion on arsenic in water by answering the following questions: What are the current federal standards for arsenic in drinking water? Is this standard the same for arsenic in drinking water in Europe? How does arsenic in water affect the body? What are some side effects?

1. Write the net ionic equation for the reaction that occurs when equal volumes of 0.256 M aqueous hypochlorous acid and sodium fluoride are mixed (there should be 2 spots before and after arrows)

at equilibrium is it product or react favored

and is the ph <, =, or > than 7?

2. Write the balanced NET IONIC equation for the reaction that occurs when hydrochloric acid and potassium cyanide are combined. (there should be 2 spots on both sides of arrows)

Also, is the reaction classified as: strong acid + strong base, weak acid + strong base, strong acid + weak base, or weak acid + weak base?

The extent of this reaction is: below 50, 50, above 50, or 100%?

3. Write the balanced net ionic equation for he reaction that occurs when acetic acid and barium hydroxide are combined. (2 on the left and 3 spots on the right of arrows)

Also, is the reaction classified as: strong acid + strong base, weak acid + strong base, strong acid + weak base, or weak acid + weak base?

The extent of this reaction is: below 50, 50, above 50, or 100%?

Would the molecules PO₃^3-, NO₂F, and BrF₃ bond to Rh+ and what atom would serve as the donor atom? Which would be the most favorable and why?

Element: LEAD

Expectations include but not limited to physical properties (color, density, refractive index, boiling point, melting point, crystal or amorphous, etc), absorption wavelength, chemical properties, density, refractive index (if exist)most common compounds it makes, availability in nature and in daily products we use, any significance forensic science.

Tetramethylsilane (TMS) is the accepted internal standard for calibrating chemical shift ppm values for 1H, 13C, and 29Si NMR spectroscopy in organic solvents.

In 1H-NMR, the TMS peak is assigned 0 ppm. This is upfield of most proton peaks observed for organic compounds. Briefly explain why the protons in TMS appear at this upfield location in a 1H-NMR spectrum.

Considering the range of hertz values possible for a spectrometer, why is the ppm scale used? To what does the ppm scale refer?

How many molecules of ATP are produced for each unit of GTP formed in the citric acid cycle?

A solution contains Al 3 + and Co 2 + . The addition of 0.3488 L of 1.779 M NaOH results in the complete precipitation of the ions as Al ( OH ) 3 and Co ( OH ) 2 . The total mass of the precipitate is 22.32 g . Find the masses of Al 3 + and Co 2 + in the solution.

Answer these 2 questions

1. Predict how a buffer of HA and A- will resist change in pH when a strong acid is added. Write down a reaction to represent your prediction.

2. Acetic acid is CH3COOH, the Ka for acetic acid is 1.8x10-5.  

   1. Write the dissociation reaction for acetic acid.

   2. Calculate the pH of a 0.240 M acetic acid solution.

   3. Why would sodium acetate need to be added to acetic acid to create a buffer?

   4. Once the buffer of acetic acid and sodium acetate is made write a reaction showing how the buffer resist a change in pH when HCl(aq) is added.

   5. Once the buffer of acetic acid and sodium acetate is made write a reaction showing how the buffer resist a change in pH when NaOH(aq) is added.

Using the appropriate K_sp values, find the concentration of Cu²⁺ ions in the solution at equilibrium after 650 mL of 0.45 M aqueous Cu(NO₃)₂ solution has been mixed with 500 mL of 0.25 M aqueous KOH solution. (Enter in M.) (K_sp for Cu(OH)₂ is 2.6x10^-19).AND find the concentration of OH^? ions in this solution at equilibrium. (Enter in M.)

(1)    Think of (or find) a medication you have taken or otherwise know about. Research that medication and report the following:

a.    Trade Name and picture of medication

b.    Generic Name

c.    CAS Number

d.    What is it used for?

e.    Upload the structure of the molecule to the Resources area in your Workspace and embed it in your post by linking to it. Or, you can directly link to it on the web if the picture is on its own webpage.

f.     Identify the common functional groups on your molecule (see Table 18.7 in the text).

g.    On what part of the body, system in the body or receptors in the body does this medication act on?

h.    If your medication

The energy density of starlight in interstellar space is 10–15 J/m3. If the average wavelength of starlight is 500 nm, what is the corresponding density of photons per cubic meter of space? (photons/m3)

For each of the following solutions, calculate the initial pH and the final pH after adding 0.010 mol of NaOH.

PART A: For 240.0 mL of pure water, calculate the initial pH and the final pHpH after adding 0.010 mol of NaOH (pH initial,pH final)

PART B: For 240.0 mL of a buffer solution that is 0.200 MM in HCHO2 and 0.275 MM in KCHO2 calculate the initial pH and the final pHpH after adding 0.010 mol of NaOH(pH initial,pH final)

PART C: For 240.0 m of a buffer solution that is 0.305 MM in CH3CH2NH2 and 0.275 MM in CH3CH2NH3Cl, calculate the initial pH and the final pHpH after adding 0.010 mol of NaOH.(pH initial,pH final)