5. How many kJ of energy are required to change 1.00 m^3 of pure water by 1.0*C? Assume a perfect system. The specific heat of the water is 4.184 J/g*C. The density of water is 1.000 g/mL.

6. 2.500 grams of metal X (molar mass 65.39 g/mole) was reacted with 100.0 mL of a 1.500 M HCl solution in a coffee cup calorimeter. The temperature went from 12.50 *C to 40.50 *C. Determine the reaction enthalpy per mole of metal X. The specific heat of the solution is 4.184 J/ g*C. Assume a solution density of 1.00 g/mL and a perfect system.

7. 20.12 grams of butane, C4H10, was combusted with oxygen in a bomb calorimeter. The temperature of .500 kg of water went from 5.00 *C to 25.89 *C. The specific heat of the water is 4.184 J/g*C. Assume a solution density of 1.00 g/mL. Determine the heat (kJ) evolved per mole of butane. Assume a perfect bomb calorimeter.

Dinitrogen Pentoxide (N2O5) decomposes in chloroform as a solvent to yield NO2 and O2. The decomposition is first order with a rate constatnt at 50 degrees Celcius 1.75 x 10^{-5 s-1}. Calculate the partial pressure of O2 produce from 1.00L of 0.500 M N2O5 solution at 50 degrees celcius over a period of 18.0 hours if the gas collected in a 10.0L container. (Assume that the products do not dissolve in chloroform.)

he decomposition of ozone in the upper atmosphere is facilitated by NO. The overall reaction and the rate law are O3(g)+O(g)→2O2(g) Rate=k[O3][NO] Write a mechanism that is consistent with the rate law.

What is the pH of a 0.136 M monoprotic acid whose Ka is 5.7 10-4?

3. Consider the following possible ligands. For which of these do you expect back-bonding to be significant in their complexes? For those that you do not expect to participate in back-bonding, explain why.

H2       CO       Br2       O2       NO

A liter of pH 7.20 phosphate buffer is needed for a certain experiment. The Henderson-Hasselbach equation will be sufficiently accurate for your determination of pH. The pK’s for possibly relevant phosphate species are:

H3PO4 ↔ H2PO4- + H+ pK = 2.15

H2PO4- ↔ HPO4-2 + H+ pK = 7.20

HPO4-2 ↔ PO4-3 + H+ pK = 12.4

0.100 Moles of H3PO4 were dissolved in about 800 mL of water, and the pH was adjusted to 7.20 using a standardized pH meter and a 1 M solution of KOH followed by addition of water to a volume of 1.00 L.

a. (10 pts) Write the equation for the charge balance to show how [K+], [H2PO4-], and [HPO4-2] are related. ([H+] and [OH-], although they are charged species, can be neglected for charge balance when compared to [K+], [H2PO4-], and [HPO4-2])

b. (10 pts) At pH 7.20 what is the ratio of [H2PO4-] to [HPO4-2]?

c. (20 pts) Combine your findings from parts a and b to determine how many mL of 1 M KOH must be added. {An important hint: By mass balance, the total molar concentration of phosphate species at pH 7.2 must equal the total molar concentration of phosphate species that was added from H3PO4.}

PLEASE ANSWER ALL PARTS, I NEED HELP. THANKS IN ADVANCE!

I have to estimate, to the nearest degree, the temp. at which the vapor pressure of a solution (3.9g benzene, 4.6g toluene) reaches 1 atm. I believe the mole fractions are .73 for benzene, and .26 for toluene.

A 25.0 mL sample of 0.125 molL−1 pyridine (Kb=1.7×10−9) is titrated with 0.100 molL−1HCl.

Part A

Calculate the pH at 0 mL of added acid.

Express your answer using two decimal places.

Part B

Calculate the pH at 10 mL of added acid.

Express your answer using two decimal places.

Part C

Calculate the pH at 20 mL of added acid.

Express your answer using two decimal places.

Part D

Calculate the pH at equivalence point.

Express your answer using two decimal places.

Part E

Calculate the pH at one-half equivalence point.

Express your answer using two decimal places.

Part F

Calculate the pH at 40 mL of added acid.

Express your answer using two decimal places.

Part G

Calculate the pH at 50 mL of added acid.

Express your answer using two decimal places.

The pKb values for the dibasic base B are pKb1 = 2.10 and pKb2 = 7.59. Calculate the pH at each of the following points in the titration of 50.0 mL of a 0.85 M B(aq) with 0.85 M HCl(aq).

(a) before addition of any HCl (b) after addition of 25.0 mL of HCl (c) after addition of 50.0 mL of HCl (d) after addition of 75.0 mL of HCl (e) after addition of 100.0 mL of HCl

The reaction of nitric oxide (NO(g)) with molecular hydrogen (H2(g)) results in the formation of nitrogen and water as follows: 2NO (g) + 2H2(g)...> N2(g) + 2H2O(g) The experimentally determined rate-law expression for this reaction is first order in H2(g) and second order with NO(g).

a) Is the reaction above, as written an elementary reaction?

b) One potential mechanism for this reaction is as follows: H2(g) + 2NO(g)...> N2O (g) + H2O (g) k1 H2(g) + N2O (g)...> N2(g) + H2O(g) k2 Is this mechanism consistent with the experimental rate law? If not, why?

c) An alternative mechanism for the reaction is:

2NO(g) <...> N2O2(g) (fast) k1(fwd) k-1(rev) H2(g) + N2O2 (g)...> N2O(g) + H2O(g) k2 H2(g) + N2O (g)...> N2(g) + H2O(g) k3

Show that this mechanism is consistent with the experimental law.

I need a good explanation for just part b please

BIOCHEM

PLEASE ONLY ANSWER IF YOU TRULY UNDERSTAND IT!! I posted this many times, and people have been giving wrong answers. Also ONLY answer if you can answer it correctly and FULLY. Also a brief explanation helps! Thank you!

2) The double helix of B-form DNA is stabilized most significantly by:

A) nonspecific base-stacking interactions between two adjacent bases in the same strand

B) hydrogen bonding between the phosphate groups of two side-by-side strands

C) covalent bonds between the 3’-end of one stand and the 5’-end of the other

D) hydrogen bonds between the ribose of each strand

3) The DNA oligonucleotide abbreviated 5’-pATCGAC-3’ (the p indicated a phosphate on the 5’-end):

A) has an A at its 3’ end

B) has 6 phosphate groups

C) has a phosphate on its 3’ end

D) violates Chargaff’s rules

4) Which of the following is a palindromic sequence?

A) GGATCC

B) GTATCC

C)GAATCC

D) CCTTCC CCTAGG CATAGG CTTAGG GGAAGG

6) What is the principal effect of UV light on DNA?

A) melting of B-form helices

B) production of T-dimers

C) deamination of cytosine residues

D) oxidation of guanosine residues

7) Chargaff’s rules state that in typical DNA:

A) A = G

B) A = C

C) A + T = G + C

D) A + G = T + C

8) In the Watson-Crick structure of DNA, the:

A) nucleotides are arranged in the A-form

B) 2’-hydroxyl groups in ribose sometimes participate in hydrogen bonding

C) two strands are antiparallel

D) purine content must be the same in both strands

9) The recognition site of some restriction enzymes are listed below. Which will not produce a “sticky end”?

A) GA↓ATTC

B) CCC↓GGG

C) C↓TCGCG

D) all will produce “sticky ends”

10) Proteins that cut DNA to unwind it are called:

A) helicases

B) topoisomerases

C) ligases

D) endonucleases

Why is H₂ more acidic than NH₃?

Calculate the theoretical and percent yield of terephthalic acid, based on PET being the limiting reagent.

MW terephthalic acid= 166.13 g/mol

MW PET= 192 g/mol

Mass of product = 0.76 g