You need to prepare 100.0 mL of a pH=4.00 buffer solution using 0.100 M benzoic acid (pKa = 4.20) and 0.220 M sodium benzoate. How much of each solution should be mixed to prepare this buffer?

a) mL of benzoic acid

b) mL of sodium benzoate

2. A mixture weighing 42.500 g contains 7.500 g NH4Cl, 19.650 g SiO2. With the remainder being NaCl. Find the percent by weight of each component. Show your calculations.

Calculate the [H3O+] of the following polyprotic acid solution: 0.135 M H3C6H5O7.

Express your answer using two significant figures.

Calculate the pH of this solution

Express your answer to two decimal places.

pH Dependence of Drug Absorption lab

1. Calculate the amount of Na₂HPO_{4 *} 7H₂O ( in grams) needed to make 50 mL of a 0.40 M solution.

2. Calculate the amounts of Na₂HPO₄ and NaH₂PO₄ (in grams) needed to prepare 200 mL of a buffer with pH=8.25 so that the sum of concentrations of HPO₄^2- and H₂PO₄^- ions is 0.5 M. pK_a1=2.12, pK_a2=7.21, pK_a3= 12.38

* on this problem I think you use the Henderson-Hasselbalch equation, but after that I'm lost.

3. Write the equation for the ionization of 3-aminophenol. Would this substance be more soulble in water at pH=2 or pH= 8? Would you expect this substance to be absorbed into the blood stream in the stomach or the instestines?

4. How does the initensity of the spot on the silica sheet relate to the solubility of the drug in the aqueous phase?

Please explain the the problems!!

A charge neutral macrocyclic ligand having four donor atoms froms a red, diamagnetic complex of Ni(II). The counter ions for this complex is the very weak Lewis base, ClO4-. When ClO4- is replaced by thiocyanate, violet complex forms.

a. Draw the structures of the red and violet complexes such that thier geometires can be decerned based only on your drawings.

b. Draw the d-orbital slitting diagrams of the red and violet complexes such that the relative energies of the orbitals in the two complexes can be compared.

c. Wse your orbital diagrams to show were the d electroms reside in each complex. Explain your electron configurations.

d. describe an experiment that you could do to test whether your predicted electron configurations are reasonable. Show what the results of this experiment would be for the d electron configureation that you showed in part c

Approximately 10000 anti-protons were synthesized and stored in a magnetic containment device at a particle accelerator facility. Due to the containment failure, the amount of antimatter annihilated completely. Calculate the energy that was release ( in Jules) as the result of this nuclear annihilation reaction.

Hint: The annihilation energy can be calculated using Einsten's most famous equation: E=MC2

where E is the energy, is the mass of matter- antimatter in the reaction, and c is the speed of light.

What is meant by the term steady state?

NH3 is a weak base (Kb = 1.8 × 10–5) and so the salt NH4Cl acts as a weak acid. What is the pH of a solution that is 0.019 M in NH4Cl at 25 °C?

Consider a solution that is 1.5×10−2 M in Ba2+ and 1.9×10−2 M in Ca2+.

What minimum concentration of Na2SO4 is required to cause the precipitation of the cation that precipitates first?

Minimum Na2SO4 required to cause PPt is 7.1×10^−9.

What is the remaining concentration of the cation that precipitates first, when the other cation just begins to precipitate?

During the dehydration experiment, C2H4(g) and unreacted C2H5OH(g) passed through the tube into the water. The C2H4 was quantitatively collected as a gas, but the unreacted C2H5OH was not. Explain this observation in terms of the intermolecular forces between water and each of the two gases.

A 200-L home heater tank contains butane gas (C4H10) at 26.0 °C. When some of the butane
is removed and burned in excess air, the pressure in the tank drops from 2.34 atm to 1.10 atm.
The energy generated in the combustion is then used to raise the temperature of 132.5 L of
water from 19.0°C to 71.3 °C.
Useful Information:
ΔH°f (CO2 (g)) = –393.5 kJ/mol ΔH°f (H2O (l)) = –285.8 kJ/mol Density of water = 1 g/mL

→Calculate the enthalpy of formation (ΔH°f) of butane gas.

cetylsalicylic acid, a monoprotic weak acid, is the active ingredient in aspirin. Two aspirin tablets, each containing 500.0 mg of acetylsalicylic acid, are dissolved in 25.0 mL water. a. Calculate the pH of the solution. b. Calculate the percent ionization of acetylsalicylic acid in the solution. (2 pts)

The following reaction can occur when a match is struck:

KClO3(s) + 3 P4(s) ------- > 3 P4O10(s) + 10 KCl(s)

(a) How many grams of KCl(s) can be produced from 38.56 milligrams of P4 assuming that we have a sufficient amount of KClO3 present?

(b) In a separate experiment, how many molecules of P4O10(s) can be obtained from 0.00625 moles of KClO3? Assume we have a sufficient amount of P4.