A 1.00-g sample of piperazine hexahydrate is dissolved in enough water to produce 100.0 mL of solution and is titrated with 0.500 M HCl.

A.) What is the initial pH of the solution, before any titrant is added?

B.) The percent neutralization points for a titration indicate the percent of the reagent that has reacted. For example, at the 25% neutralization point for piperazine, 75% (0.75×[Pip]) of the base remains, and 25% is neutralized to form PipH+.

Calculate the pH at the 25%, 50%, and 75% neutralization points of the first neutralization, respectively.

C.) What is the pH at the first equivalence point?

D.) The percent neutralization points for a titration indicate the percent of the reagent that has reacted. For example, at the 25% neutralization point for PipH+, 75% (0.75×[PipH+]) of the base remains, and 25% is neutralized to form PipH22+.

Calculate the pH at the 25%, 50%, and 75% neutralization points of the second neutralization, respectively.

Please show all work!

How is the operon activated in E.coli that grow on lactose?

(a) A vessel is separated into two parts, A and B, by a bilayer lipid membrane containing Na+ channels. Part A holds an aqueous solution of NaCl with concentration 0.15 mol L-1 and of disaccharide sucrose with concentration 0.01 mol L-1 . Part B holds an aqueous solution of NaCl with concentration 0.015 mol L-1 . Calculate the electrical potential between the two sides of the membrane at 30 oC and at 50 oC. Neglect the effect of temperature on the molarity of the solutions. Assume that the membrane is not permeable for glucose and for Cl ions.

What conditions must be true about a weak acid solution in order to use the Henderson‐Hasselbalch equation to find solution pH and in what region of a titration curve do these conditions exist?

Match each term to the correct definition.

A. Chemical separation

B. Gravity filtration

C. Physical separation

D. Vacuum filtration

E. Evaporation

F. Heterogeneous mixture

G. Homogenous mixture

H. Distillation

I. Extraction

J. Decantation

-varies in composition, distinct clumps of each component appear in the mixture

-uniform in composition, the components cannot be visually distinguished

-uses heat to remove a volatile solvent from a dissolved solution, leaving behind the non-volatile components as a solid residue

-exploit some difference in the physical properties of two species in order to separate them

-exploit reactivity to convert one component to a new species which can be easily separated from the other components that are present

-uses a solvent to selectively dissolve one component while leaving other components in the solid state

-uses gravity to pull the liquid through a filter paper to separate a liquid from a solid

-uses a vacuum to pull the liquid through a filter paper to separate a liquid from a solid.

-The process of pouring a solution off a heavy solid that settles to the bottom of the container

-Takes advantage of the difference in the boiling point between the two components

What volume (to the nearest 0.1 mL) of 5.20-M NaOH must be added to 0.500 L of 0.350-M HNO₂ to prepare a pH = 3.50 buffer?

A gaseous mixture contains 421.0 Torr of H2(g), 392.9 Torr of N2(g), and 68.1 Torr of Ar(g). Calculate the mole fraction, X, of each of these gases.

Some commercial drain cleaners contain a mixture of sodium hydroxide and aluminum powder. When the mixture is poured down a clogged drain, the following reaction occurs:

2NaOH(aq) + 2Al(s) + 6H₂O(l) → 2NaAl(OH)₄(aq) + 3H₂(g)

The heat generated in this reaction helps melt away obstructions such as grease, and the hydrogen gas released stirs up the solids clogging the drain. Calculate the volume of H₂ formed at 23°C and 1.00 atm if 3.12 g of Al are treated with an excess of NaOH.

The metabolic oxidation of glucose, C₆H₁₂O₆, in our bodies produces CO₂, which is expelled from our lungs as a gas:

C₆H₁₂O₆(aq) + 6O₂(g) → 6CO₂(g) + 6H₂O(l)

Calculate the volume of CO₂ produced at body temperature (37°C) and 0.970 atm when 24.5 g of glucose is consumed in this reaction.

Calculate the volume of oxygen you would need, at 1.00 atm and 298 K, to completely oxidize 50.0 g of glucose.

Ammonia (NH₃) boils at -33.4 ^oC. It has an enthalpy of vaporization of 23.35 kJ/mol. The liquid has a specific heat of 80.8 J/mol ^oC, and the gas has a specific heat of 35.06 J/mol ⁰C.

A 34.06 gram sample of ammonia was heated, at 1 atmosphere pressure, from -40 ^oC to room temperature (25 ^oC). How many kJ of thermal energy did the sample absorb from the surroundings in this process?

I got 101263.8J (101.3kJ) and it is NOT correct, please help with the correct answer.

you want to purify 10g of a compound A that has been contaminated with 0.20g of compound B. solubilities in water of the two compounds are given.

compound A - solubility at 20°c= 0.029g/mol, solubility at 100°c= 0.680g/mol

compound B - solubility at 20°c = 0.22, solubility at 100°c = 6.67

a) what volume of boiling water is needed to dissolve 10g of compound A?

b) How much of compound A will remain after cooling to 20°c?

c) what is the maximum amount of compound A that can be recovered in the first crop of this recrystallization?

d) will any compound B crystals form ( will compound B be pure)? show work to explain answer.

make an energy level diagram (electronic transitions) of compound Fluorescein

Using a 0.25 M phosphate buffer with a pH of 7.6, you add 0.75 mL of 0.45 M NaOH to 59 mL of the buffer. What is the new pH of the solution?

The generic metal A forms an insoluble salt AB(s) and a complex AC5(aq). The equilibrium concentrations in a solution of AC5 were found to be [A] = 0.100 M, [C] = 0.0340 M, and [AC5] = 0.100 M. Determine the formation constant, Kf, of AC5. The solubility of AB(s) in a 1.000-M solution of C(aq) is found to be 0.163 M. What is the Ksp of AB?

1.What are the key operating features of the following types of mass spec instruments and what are the advantages and benefits if any associated with each type. (Include quadrupole, triple quadrupole mass spec, ion trap and time of flight) 2. Briefly describe what is Maldi

An unknown mass of each of the following substances, initially at 21.0 ∘C, absorbs 1930 J of heat. The final temperature is recorded as indicated. Find the mass of each substance.

1) Pyrex glass (Tf= 55.7 ∘C)

2) sand (Tf= 62.3 ∘C)

3) ethanol (Tf= 44.4 ∘C)

4) water (Tf= 32.4 ∘C)