For each of the following side chain interactions in a protein, give an example of two amono acids that interact that way and draw a structure that illustrates the interaction.

a. Hydrophobic interaction, b. Metal ion coordination, c. Covalent bond (in the side chain), d. Hydrogen bonding, e. Salt bridge

In Acid - Base equilibria  problems, how do you know what are the major species. I mean what do " major species " mean exactly?

  19. The pH of a solution prepared by mixing 50.0 mL of 0.125 M NaOH and 40.0 mL of

0.125 M HNO₃ is ____

   [A] 13.29 [B] 8.11 [C] 11.00 [D] 12.14 [E] 7.00

20. The pH of a solution prepared by mixing 50.0 mL of 0.125 M KOH and 50.0 mL of 0.125 M HCl is ______

[A] 1.34 [B] 5.78 [C]1.90 [D] 1.14 [E] 7.0

21. Consider the following table for K_sp values

Which will have the least solubility in the given solvent?

[A] CdCO₃ [B] Cd(OH)₂ [C] CdF₂ [D] AgI [E] ZnCO₃

  22. What is the molar solubility of magnesium oxalate ( MgC₂O₄) in water? The solubility-

   product constant for MgC₂O₄ is 8.6 x 10^-5 at 25 °C.

[A] 4.07 [B] 1.7 x10^-4 [C] 1.3 x10^-2 [D] 4.3 x10^-5 [E] 9.3 x10^-3

The enthalpy change for the following reaction is -748 kJ. Using bond energies, estimate the C≡O bond energy in CO(g). 2CO(g) + 2NO(g)2CO2(g) + N2(g)

The inversion of compound B is experimentally determined to follow the rate law: d[B]/dt = -k[B]^a[H⁺]^b.
At 25 °C and a constant pH of 3.00, the reaction proceeds with a constant half-life of 40.0 min. At this same temperature, but at a constant pH of 1.00, the half-life is constant at 4.00 min. What are the exponents (orders) a and b in the above rate law?

Like nickel, iron can also be purified using a carbonyl compound. Iron purified this way is called carbonyl iron, and the iron has an oxidation state of zero. Briefly rationalize why iron(III) does not form a complex with carbonyls whereas iron(0) does. Based on the EAN rule, speculate on the most likely homoleptic carbonyl complex formed by iron(0).

Consider the titration of a 36.0 mL sample of 0.170 M HBr with 0.200 M KOH. Determine each of the following:

Part A

the initial pH

Express your answer using three decimal places.

Part B

the volume of added base required to reach the equivalence point

Express your answer in milliliters.

Part C

the pH at 12.0 mL of added base

Express your answer using three decimal places.

Part D

the pH at the equivalence point

Express your answer as a whole number.

Part E

the pH after adding 5.0 mL of base beyond the equivalence point

Express your answer using two decimal places

Calculate the pH for each of the following cases in the titration of 50.0 mL of 0.160 M HClO(aq) with 0.160 M KOH(aq). The ionization constant for HClO can be found here....4.0*10-8

before addition of KOH?

After addition of 25.0 mL KOH?   Addition of 30.0 mL KOH?    50.0 mL KOH?    60.0 mL KOH?

For each of the following reactions, calculate ?H?rxn, ?S?rxn, ?G?rxn at 25?C. State whether or not the reaction is spontaneous. If the reaction is not spontaneous, would a change in temperature make it spontaneous? If so, should the temperature be raised or lowered from 25?C?

2CH4(g)?C2H6(g)+H2(g)

?H?rxn, ?S?rxn, ?G?rxn at 25?C???

Calculate the molarity of a solution prepared by dissolving 12.3g of Na2CrO4 in enough water to produce a solution with a volume of 900.mL . Express the molarity to three significant digits.

if water had been in the pipet when you pipetted the vinegar, would the calculated molarity of acetic acid be:
lower M, higher M, or the same M
if water had been in the erlenmeyer into which you added the vinegar, would the calculated molarity of acetic acid be:
lower M, higher M, or same M
if water had been in the burr into which you poured NaOH solution, would the calculated molarity of acetic acid be:
lower M, higher M, same M
you pumped vinegar into a beaker to bring to your bench. if there had been water in that beaker, would the calculated molarity of acetic acid be:
lower M, higher M, same M
you took NaOH solution from a carboy into a beaker to bring to your bench. if there had been water in the beaker, would the calculated molarity of acetic acid be:
lower M, higher M, same M

A sediment sample taken from a lignite strip-mine pit contains highly alkaline (pH 10) water. Cations were displaced from the sediment by treatment with HCl. A total analysis of cations in the leachate yielded, on the basis of millimoles per 100 g of dry sediment: 160 mmol Na⁺, 10 mmol K⁺, 30 mmol Mg²⁺, and 70 mmol Ca²⁺. What is the cation exchange capacity of the sediment in milliequivalents per 100 g of dry sediment? Why does H⁺ not have to be considered in this case?

A reaction takes place in a balloon such that 425 J of heat are taken in from the surroundings and 193 J of work are done by the surroundings.

What is ΔE for the system? in J

What is ΔH for the surroundings? in J

What is ΔE for the universe? in J

The compound 4-methyl pyrazole (appropriate KI is 0.15 uM) is currently being used as a treatment for methanol poisoning. How would the effectiveness of 4-methyl pyrazole compare with the effectiveness of a formamide treatment (appropriate KI is 0.712 uM)?

A titrimetric method for the determination of calcium in limestone was tested by analysis of a NIST
containing 30.15% CaO. The mean result of four analyses was 30.26% CaO, with standard deviation of 0.085%.
By pooling data from several analyses, it was found that s = 0.094% CaO.
a) Do the data indicate the presence of a systematic error at the 95% confidence level?
b) Would the data indicate the presence of a systematic error at 95% confidence level if no pooled value for s
had been available?
Show calculations for part a and b.