You are titrating 25 mL of 0.25 M Ascorbic Acid solution ith 0.15 M NaOH. Ascorbic Acid is an organic diprotic acid, H2A, that is found in many natural materials. Ka1 = 7.94 x 10^-5 and Ka2 = 1.62 x 10^-12. What is the a) initial pH, b) at the 1st equivalence point, c) the 2nd equivalence point, and d) after 27.5 mL of NaOH have been added?

In the precipitation reaction Na₂(C₂O₄)^2- (aq) + CaCl₂ (aq) -----> Ca(C₂O₄) (s) + 2NaCl (aq), how do I determine how many grams of the reactants I need to yield 5 grams of the precipitate?

The active ingredient in a zinc nutritional supplement is ZnSO4·7H2O (molar mass = 287.58 g/mol). Ten zinc tablets containing a mix of the active ingredient and an inactive filler were ground and mixed together thoroughly. The total mass of these ten tablets was 11.890 g. A 2.242 g sample of the finely ground tablets was dissolved in an acidic solution. The solution was neutralized with ammonia and subsequently warmed in a water bath. Addition of (NH4)3PO4 to the solution resulted in the precipitation of ZnNH4PO4. The precipitate was filtered and dried, then ignited to produce 0.180 g of Zn2P2O7 (molar mass = 304.76 g/mol).

1- What is the mass percent of ZnSO4·7H2O in each tablet?

2 and 3- What is the average mass of the active ingredient ZnSO4·7H2O and inactive filler in each tablet?

Determine the thermochemical equation for the oxidation of one mole of sucrose by a biological system.   (That means write a balanced chemical equation AND its enthalpy of reaction.)

Is the reaction gaining or losing entropy, S? Prove your answer with a calculation.

Determine the energy generated by eating one serving of Jelly Bellies, NOT from the package calorie list, but by calculating based on the grams of sucrose per serving of Jelly Bellies.

Can all nuclei be studied by NMR? What property of a nucleus determines whether it is NMR active?

Name the acid used in baking powder and what role does it do in baking

Discuss the chemistry of the peroxo complexes of chromium(IV), (V), and (VI). (b) Discuss the electronic structure of Mn(III) compounds. (c) Discuss using suitable examples, the chemistry of manganese(IV) complexes.

1.) Explain the advantages of a FT instrument over a constant wavelength diffuse instrument.

2.) Explain why Infrared spectroscopy uses interferometers rather than constant wavelength spectrometers.

1) For a first-order reaction, after 230s, 33% of the reactants remain. Calculate the rate constant for the reaction.

2) A compound decomposes with a half-life of 80s and the half-life is independent of the concentration. How long does it take for the concentration to decrease to one-ninth of its initial value?

1- does an alkyl substiuent in a ring favor the Friedel-Craft reaction?

2- what is the advatage of using tetramethylthiourea?

3 - what is the reagent(s) used for the thiolization of alkyl halides?

4- what is the use of the press in IR?

If 01.2 KOH is mixed with 0.05g of CO2 according to the following equation, 2KOH + CO2 -----> K2CO3+ H2O

a. What is the limiting reactant? ______________________

b. How many grams of K2CO3can be produced? ________________

c. What is the excess reactant? __________________

d. If 0.16g of K2CO3isolated, what is the % yield?

1. If the enzyme-catalyzed reaction E + S ↔ ES ↔ E + P takes place near Vmax to the enzyme (E), what can be concluded about the relative concentrations of S and ES?

a) High [S], [ES] is low

b) High [S], [ES] are at their maximum

c) Low [S], [ES] is low

d) Low [S], [ES] is at its maximum

2. Which of the following statements about Michaelis-Menten kinetics is correct?

a) Km = the substrate concentration required for the reaction to reach Vmax

b) Km = dissociation constant of the enzyme-substrate complex

c) Km = is a measure of the substrate's affinity for the enzyme

d) Km = expression of reaction rate

3. What is the Km value if the substrate concentration is 25 mM and the initial reaction rate is half Vmax for an enzyme catalyzed reaction?

a) Km = 50 mM

b) Km = 12.5 mM

c) Km = 625 mM

d) Km = 25 mM

Explain why we need/want a large magnetic field in NMR based on the following concepts:

a. kT and the Boltzmann distribution

b. the energy difference between the ground and excited states

c. the net magnetization of the sample

You decide to construct a zinc/aluminum galvanic cell in which the electrodes are connected by a wire and the solutions are connected with a salt bridge. One electrode consists of an aluminum bar in a 1.0 M solution of aluminum nitrate. The other electrode consists of zinc bar in a 1.0 M solution of zinc nitrate.

a. Which electrode is the cathode and which is the anode?

b. What is the direction of electron flow?

c. What chemical reactions are occurring at each electrode?

d. What is the overall balanced chemical reaction?

e. After a period of time, will the bar of zinc become heavier, lighter or stay the same? What about the aluminum bar?

f. What is the standard cell potential?

1. The stopcock connecting a 1.00 L bulb containing krypton gas at a pressure of 414 mm Hg, and a 1.00 L bulb containing oxygen gas at a pressure of 792 mm Hg, is opened and the gases are allowed to mix. Assuming that the temperature remains constant, what is the final pressure in the system?

mm Hg

2. A mixture of oxygen and helium gases is maintained in a 5.33 L flask at a temperature of 13°C. If the partial pressure of oxygen is 0.432 atm and the partial pressure of helium is 0.314 atm, what is the total pressure in the flask?

atm