How do alpha-helices create different surfaces (such as a hydrophobic side)?

Problem 1: For the reaction 2CH₃OH_(l) + 3O_2(g) = 2CO₂ + 4H₂O_(l) I calculated that the change in molar entropy of the system is 313.7 Joules/(moles*kelvin). The question then asked what is the entropy change of the system when 2.35 moles of O₂ react. I multiplied 313.7 Joules/(moles*kelvin) by 2.35 moles of O₂ and also divided by 3 moles of O₂ because of the "3" coefficient, and got 246 Joules/kelvin and I just want to make sure that last part was correct. Specifically, was I correct to both multiply by 2.35 and divide by 3.

Problem 2: Very similar problem. For the reaction H_2(g) + F_2(g) = 2HF_(g) I calculated that the change in molar entropy of the surroundings is 1,819 Joules/(moles*kelvin). The question then asked to calculate the entropy change of the surroundings when 2.15 moles of H_2(g) react, so I multiplied 1,819 Joules/(moles*kelvin) by 2.15 moles of H_2(g) and then divided by 1 moles of H_2(g) since the coefficient is "1" and got 3,911 Joules/kelvin, and I just want to make sure this last part is correct. Specifically, was I correct to multiply by 2.15 and then divide by 1

Hydrazine, NH2NH2, is a weak base. The following is the equilibrium equation for its reaction with water:

NH2NH2(aq) + H2O(l) <----------> NH2NH3+(aq) + OH-(aq)     Kb = 8.5 x 10-7

What is the hydronium ion concentration, [H3O+], in a 2.03 M NH2NH2 solution?

When a strong acid is neutralized by a weak base is the neutralization complete? Write the neutralization reaction for HClO4 and NH3. What is the value of Kn (equilibrium constant for neutralization)? (Kb(NH3)=1.810‒5) If stoichiometric amounts of acid and base are reacted will the resulting solution be acidic, basic or neutral?

When running chromatography, one way to improve resolution and decrease peak width is by dropping the flow rate.

a. Which variable in the van demter equation does this influence and how? (please explain and use descriptive names not just letter variable in the equation).

b. when is this not an advantage? (please explain).

What mass of AgCl can be prepared by the reaction of 100.0 ml of 0.20 M aqueous AgNO3 with 100.0 ml of 0.15 M CaCl2? Write the molecular and net ionic equations.

Solve for the new pressure in each of the following, with n and V constant:

aA gas with a pressure of 1.25

atm at 60 ∘C is cooled to -24 ∘C.

b. A sample of

N2 with a pressure of 760 mmHg at -70 ∘C is heated to 34 ∘C.

A volume of 25.0mL of a 0.10M aqueous solution of acetic acid(HC₂H₃O₂ or HOAc or CH₃CO₂H, Ka=1.8x10^-5) is titrated with 0.080M NaOH.

What is the pH Initially

After 10.0mL of NaOH has been added

At the halfway point

After 20.0mL of NaOH has been added

At the equivalence point

And after 40.0mL NaOH has been added

Calculate the pH for each of the following cases in the titration of 25.0 mL of 0.100 M pyridine, C5H5N(aq) with 0.100 M HBr(aq):

(a) before addition of any HBr

(b) after addition of 12.5 mL of HBr

(c) after addition of 24.0 mL of HBr

(d) after addition of 25.0 mL of HBr

(e) after addition of 37.0 mL of HBr

You need to prepare an acetate buffer of pH 5.52 from a 0.881 M acetic acid solution and a 2.64 M KOH solution. If you have 875 mL of the acetic acid solution, how many milliliters of the KOH solution do you need to add to make a buffer of pH 5.52? The pKa of acetic acid is 4.76.

A-

What is the pH of a buffer prepared by adding 0.405 mol of the weak acid HA to 0.305 mol of NaA in 2.00 L of solution? The dissociation constant Ka of HA is 5.66×10−7.

Express the pH numerically to three decimal places.

B-

What is the pH after 0.150 mol of HCl is added to the buffer from Part A? Assume no volume change on the addition of the acid.

Express the pH numerically to three decimal places.

C-

What is the pH after 0.195 mol of NaOH is added to the buffer from Part A? Assume no volume change on the addition of the base.

Express the pH numerically to three decimal places.

The buffer system in human blood buffer is composed of HCO₃^- and H₂CO₃. (The K_a for carbonic acid is 7.9 x 10 ^-7).

a. Please identify the acidic and basic component of the buffer.

b. Please write the chemical equation that will happen when additional HCl is added into the buffer. (Hint: acids like to react with bases.)

c. Please write the chemical equation that will happen when additional NaOH is added into the buffer. (Hint: bases like to react with acids.)

d. What is the effective buffer range?

e. In order for our body to function properly, the pH of blood needs to be maintained between 7.35-7.45. If the pH of the buffer is measured to be 7.40, what is the ratio between HCO₃^- and H₂CO₃?

f. If the concentration of HCO₃^- is 5 times that of H₂CO₃, what is the pH of the buffer?

A gaseous mixture of O2 and N2 contains 40.8 % nitrogen by mass. What is the partial pressure of oxygen in the mixture if the total pressure is 385 mmHg ? Express you answer numerically in millimeters of mercury.

Three gases (8.00 g of methane, CH4, 18.0 g of ethane, C2H6, and an unknown amount of propane, C3H8) were added to the same 10.0-L container. At 23.0 ∘C, the total pressure in the container is 4.60 atm . Calculate the partial pressure of each gas in the container. Express the pressure values numerically in atmospheres, separated by commas. Enter the partial pressure of methane first, then ethane, then propane.

Which would be the best emulsifier of soil if soft water (no Ca²⁺ ions, Mg²⁺ ions, and so on) were used?

a. A soap.

b. A detergent.

c. Both would be about the same.

Explain your answer: ________________________________