a) From the list below, pick an acid, along with its conjugate base, that can be used to make a pH 7.40 buffer.

H3PO4 Ka = 6.9 x 10-3 H2PO4- Ka = 6.4 x 10-8 HPO42- Ka = 4.8 x 10-13

b) If you have 0.100 M solutions of the acid and the conjugate base in the system that you picked and there was 20.0 mL of the base, how many mL of the acid would you need to make this buffer of pH 7.40?

76

What is the total sample size (in grams) for a sample of ethanol (CH₃CH₂OH) which contains 2.51 g of oxygen?

77.

What is the total sample size (in grams) for a sample of sodium nitrite which contains 3.54 g of oxygen?

What is the pH at the equivalence point in the titration of a 22.6 mL sample of a 0.371 M aqueous acetic acid solution with a 0.353 M aqueous barium hydroxide solution?

pH =

If a solution of NaOH has a 20% mass percent of NaOH and a density of 1.22 g/ml, what is the molarity of this solution ?

Draw a schematic diagram for a Perkin Elmer ultraviolet-visible spectrophotometer, clearly and specifically identifying each important part.  

     b. Draw a schematic diagram for a Shimadzu spectro-fluorometer, clearly and specifically identifying each important part.

     c. Compare a PM tube, a PDA, and a thermocouple with respect to two different aspects.

Use your calculated value of Ksp (1.35 x 10^-7) and Kf (1140) to explain why CdC2O4 is dissolved by ammonia.

How would the formation constant for [Cd(NH3)4 +2] be affected (increase, decrease, or no change) if not all of the CdC2O4 precipitate reacted with NH3?

1. Calculate the mean activity coefficient (g_±) for a 2.0 x 10^-3m Na₃PO₄ solution at 25 ºC.
2. Calculate the activity coefficients (g₊ and g_-) of each ion for a 2.0 x 10^-3m Na₃PO₄ solution at 25 ºC AND the value for the mean activity coefficient.

Thanks in advance!!!

The decomposition of XY is second order in XY and has a rate constant of 6.94×10−3 M−1⋅s−1 at a certain temperature.

If the initial concentration of XY is 0.160 M , how long will it take for the concentration to decrease to 6.00×10−2 M ? Express your answer using two significant figures.  

If the initial concentration of XYXY is 0.050 MM, what is the concentration of XYXY after 500 ss ?

Express your answer using two significant figures.

Reaction enthalpy for ethanol oxidation, C₂H₅OH+3O₂ -> 2CO₂ + 3H₂O is 1257 kJ/mole.

Energy content per mol fuel ______kJ                     Energy content per gram fuel = ____________ kJ

Energy released per mol CO₂ formed ________ kJ   Energy released per mol O₂ consumed= ______ kJ

Moles of CO₂ formed per 1000 kJ energy released ___________

a) Explain oxidative addition and carbonyl insertion reactions in organometallic chemistry with

appropriate examples.

b) Explain pictorially the σ- and π-bonding in metal-carbonyl compounds and comment on the synergistic effect.

c) What are the experimental evidences and how they support synergistic effect in metal carbonyl bonding?

Explain the sublimation and vaporization processes. How does the condensation process relate to vaporization and how does deposition relate to sublimation? Give an example of each process

1. Use this data table for the bromination of acetone to answer the following questions;

a) Determine the reaction order with respect to each of the three reactants and write the rate law.

b) What is the value of the rate constant including proper units?

For each of the transition metal complex ions
(a) [Ti(NH3)6]2+
(b) [Cr(H2O)4(OH)2]1-
(c) trans–[Pt(CN)2(en)2]2+

(i) Draw the structure of the transition metal complex ion. Show the charge on the
complex.
(ii) Determine the number of d electrons.
(iii) Draw the ground state arrangement of the d electrons in the ground state.
(iv) Calculate the LFSE (in units of Δo or ΔT) for each complex.

1) A) Draw the dipeptide Y-C at pH 7 and clearly label the peptide bond to be broken in the presence of chymotrypsin.

B) Draw the five-step mechanism for the chymotrypsin clevage of the dipeptide.

C) Label the transition state each time it is formed.

D) What mechanism is used to describe this bisubstrate reaction?

1. For the reaction: 2Mg(s) + O2(g) → 2MgO Calculate the percent yield if 10g of Mg and 15g of O2 react, and 15.0g MgO was actually obtained.

2. For the reaction: H₂(g) + Cl₂(g) → HCl(g) (is this balanced?) calculate the mass, in grams of Hydrogen Chloride produced when H₂ reacts with 25.0g Cl₂.