Determine the pH during the titration of 25.4 mL of 0.346 M HI by 0.346 M NaOH at the following points:

(a) Before the addition of any NaOH

(b) After the addition of 12.7 mL of NaOH

(c) At the equivalence point

(d) After adding 32.0 mL of NaOH

A buffer is prepared by adding 150 mL of 1.0 M NaOH to 250 mL of 1.0 M NaH₂PO₄. How many moles of HCl must be added to this buffer solution to change the pH by 0.25 units? Assume the total volume remains unchanged at 400 mL.
For H₂PO₄^-, K_a = 6.3 × 10^-8.

Based on the data above, calculate the slope of the line of the absorbance vs relative concentration for each for the four data sets (Part III in your lab manual).

Let:

αHMR
IA equal the slope for solutions A₀-A₃ at 425 mm

αMR^-
IB equal the slope for solutions B₀-B₃ at 425 mm

αHMR
IIA equal the slope for solutions A₀-A₃ at 520 mm

αMR^-
IIB equal the slope for solutions B₀-B₃ at 520 mm

These α's are the respective Beer's Law constants for HMR and MR^- at the 2 wavelengths. Enter below the α's that you determined from your Excel graphs

Consider the dissolution of calcium hydroxide:

Ca(OH)2(s) --> Ca2+(aq) + 2OH‑(aq)

K = 4.7 x 10‑6

Write the equilibrium expression for this reaction.

2. Identify whether the following actions would favor the formation of products, reactants, or have no affect upon the dissolution of calcium hydroxide. Explain each answer.

a. Addition of CaCO3 to an equilibrium mixture of calcium hydroxide and water.

b. Addition of Na2CO3 to an equilibrium mixture of calcium hydroxide and water.

c. Addition of HCl to an equilibrium mixture of calcium hydroxide and water.

d. Addition of NaOH to an equilibrium mixture of calcium hydroxide and water

2 NO(g) + Cl₂(g) --> 2 NOCl (g)

Two proposed mechanisms for the reaction are given below. Which is the better mechanism? Explain both why the better mechanism is better and why the worse mechanism is worse.

       Mechanism 1                                                        Mechanism 2

                           NO + Cl₂ --> NOCl + Cl                                       Cl₂ --> Cl + Cl

                           NO + Cl --> NOCl NO + Cl --> NOCl

NO + Cl₂ --> NOCl + Cl

For the correct mechanism, identify:

a. the rate-limiting step

b. any intermediates

c. any catalysts

Tartaric acid is a diprotic acid (H2T) present in many fruits and is
used in cosmetics due to its powerful depigmenting effect. Therefore, it is
present in multiple facial creams whose pH is 5.2. Calculate the amount of H2T that is
you must add to prepare 125 mL of a necessary tartaric acid solution in the
manufacture of such creams. Data: Ka1 = 9.2 x 10-4; Ka2 = 4.31 x10-5. PM H2T = 150.1g / mol

The enzyme is studied in the presence of a different inhibitor (inhibitor B). In this case, two different concentrations of inhibitor are used. Data are as follows:

a) Determine the apparent Vmax at each inhibitor concentration.

b) Determine the apparent KM at each inhibitor concentration.

c) Estimate KI from these data. [Hint: Calculate the K_I at 3 mM and at 5 mM; and then take the average of the two K_{I }values.]

Sodium sorbate (HS) and sodium benzoate (HBz) are additives used together
in many foods to inhibit the growth of microorganisms. In particular, it
they are present in jams in the following amounts, sodium sorbate
(150.22 g / mol) 44 mg / kg and sodium benzoate (144.11 g / mol) 26 mg / kg. 10 g of
jam and dissolve in H2O until a total volume of 70 mL is obtained. Determines
the pH of the resulting solution assuming they are the only acid / basic species
existing in the mix. Ka sorbic acid (HS) = 1.74 x 10-5, Ka benzoic acid (HBz) =6.28 x 10-5.

You need to prepare an acetate buffer of pH 5.31 from a 0.809 M acetic acid solution and a 2.81 M KOH solution. If you have 880 mL of the acetic acid solution, how many milliliters of the KOH solution do you need to add to make a buffer of pH 5.31 ? The p K a of acetic acid is 4.76.

For the reaction A+B+C→D+EA+B+C→D+E, the initial reaction rate was measured for various initial concentrations of reactants. The following data were collected:

Rate law equation

The rate of a chemical reaction depends on the concentrations of the reactants. For the general reaction between AA and BB,

aA+bB⇌cC+dDaA+bB⇌cC+dD

The dependence of the reaction rate on the concentration of each reactant is given by the equation called the rate law:

rate=k[A]m[B]nrate=k[A]m[B]n

where kkk  is a proportionality constant called the rate constant. The exponent mmm  determines the reaction order with respect to AA, and nnn determines the reaction order with respect to BB. The overall reaction order equals the sum of the exponents (m+nm+n).

Part A: What is the reaction order with respect to A? **Express your answer as an integer.

Part B: What is the reaction order with respect to B? **Express your answer as an integer.

Part C: What is the reaction order with respect to C? **Express your answer as an integer.

Calculate the percent ionization of hypobromous acid (HBrO) in solutions of each of the following concentrations (Ka = 2.5e-09.)

(a) 0.142 M

= %

(b) 0.448 M

= %

(c) 0.625 M

= %

1.            Consider the following redox reaction to produce methanol:

                                    2CH₄(g) + O₂(g) --> 2CH₃OH(g).

a. Calculate the change in enthalpy for the reaction at standard conditions using bond dissociation energies. See the b. appendix for the table of bond energies.

b. Name two things that you could do to favor the formation of methanol by this reaction.

c. Using the value of ∆H calculated in 1a, is this an exothermic or endothermic reaction? Explain your answer.

d. Methane gas is a byproduct of oil extraction and of oil refining. Release of the methane gas into the atmosphere, which contains 20% oxygen, does not result in the formation of methanol. That’s a surprising observation: Despite the fact that the reaction of methane and oxygen to produce methanol is product-favored at normal temperatures, methanol is not formed spontaneously when methane is released to the atmosphere. Suggest why no methanol is formed.

Differentiate between total ion chromatogram (TIC) and extracted ion chromatogram (EIC). Why quantification of analytes is carried out through integration of EIC?

Selected ion monitoring (SIM) is often used in determination of analytes at trace levels, (very low concentrations) provide a brief explanation why one obtains lower detection lim-its with SIM than SCAN.

Discuss the need for rapid scan or MIM data acquisition with mass spectrometers when interfaced with chromatography techniques.