1 A buffer is prepared by mixing 50.0 mL of 0.100 M acetic acid with 30.0 mL of 0.100 M sodium hydroxide and 20.0 mL of distilled water. Estimate the concentration of acetic acid in the resulting buffer. Report your answer in moles/liter, but do not include units with your answer. 2 Determine the concentration of acetate ions in the buffer solution. Report your answer in moles per liter, but do not include units in your answer. 3 Estimate the pH of the buffer solution using the Henderson-Hasselbalch equation. 4 Using the Henderson-Hasselbalch equation, estimate the pH of the buffer if an additional 10.0 mL of 0.100 M sodium hydroxide is added. 5 Estimate the pH of the original buffer if 10.0 mL of 0.100 M hydrochloric acid is added.

Calculate the change in pH when 9.00 mL of 0.100 M HCl(aq) is added to a 100.0 mL of a buffer solution that is 0.100 M in NH3(aq) and 0.100 M in NH4Cl(aq). Calculate the change in pH when 9.00 mL of 0.100 M NaOH(aq) is added to the original buffer system.

Hyrdrofluoric acid (Ka = 7.2 x 10^-4), is used in a wide range of commercial processes. HF is used for glass etching and the synthesis of pharmaceutical drugs and compounds such as teflon. One issue with HF is its corrosive nature, "Aqueous hydrofluoric acid is a contact-poison with the potential for deep, initially painless burns and ensuing tissue death." (from Wikepedia page on hydrofluoric acid).

The flouride ion is often used in dental procedures, as the F- can react with tooth enamel to form highly stable mineral fluorohydroxyapatite (which is less likely to break down in the mouth than "normal" enamel). One common form of F^- delivery is fluoride varnish, which has a F^- concentration of around 1.778 M.

Given what you know of the acid base chemistry of HF, what is the concentration of HF in an aqueous solution with a pH of 5.85?

What is the pH change when adding 0.15 moles of HCl to a 1 L buffer containing 1.0 M acetic acid and 1 M sodium acetate?

A`) decreased by 0.13 units

B) increse by 0.13 Units

C) increase by 0.15 units

D) decrese by 0.15 Units

E) no change

1.

Which of the following describes the element Cs.
Choose all that apply.

a.consists of diatomic molecules in elemental form

b.is found in nature only combined with other elements

c.reacts vigorously with alkali metals to form salts

d. is very reactive as a metal

e.forms a basic solution in water

f. is one of the group of the least reactive elements

2. Using only the periodic table arrange the following elements in order of increasing atomic radius:

boron, fluorine, oxygen, lithium

3. Using only the periodic table arrange the following elements in order of increasing atomic radius:

nitrogen, antimony, arsenic, bismuth

A 1.458-g sample of a solid, weak, monoprotic acid is used to make 100.0 mL of solution. 40.0 mL of this solution was titrated with 0.07942-M NaOH. The pH after the addition of 16.55 mL of base was 2.94, and the equivalence point was reached with the addition of 46.63 mL of base.

a) How many millimoles of acid are in the original solid sample? Hint: Don't forget the dilution.

b) What is the molar mass of the acid?

c) What is the pK_a of the acid?

Explain the rate-determining step, as discussed in General or Organic Chemistry

Draw orbital diagrams for atoms with the following electron configurations:

1. 1s²2s²2p⁶3s²3p⁶4s²3d⁷

12. Define the following terms and principles: (8 points)
    1. Heisenberg uncertainty principle
       
    2. Aufbau principle
       
    3. Pauli exclusion principle
       
    4. Hund’s rule

One method for producing hydrogen is to react coke (mostly solid carbon) with steam to make syngas, a mixture of CO and hydrogen

C(s) + H₂O(g) ⇌ CO(g) + H₂(g)     K_p = 0.45 at 900 K     ΔH = +131 kJ

What is the partial pressure of CO at equilibrium when 9.59 atm of H₂O(g) is heated with excess C(s) at 900 K?

After equilibrium is reached, CO(g) is added.

In which direction will the reaction shift?

Will the equilibrium constant, K, increase or decrease?

Complete the following table of data for Ba(NO3)2. (Assume the density of water is 1.00 g/mL.)

Use a graph of ?G vs. T to determine the following. (Enter your answers to three significant figures.)

What is the value of ?H for the system?

What is the value of ?S for the system?

The equilibrium constant (KP) is 0.16 at a particular temperature for the reaction: N₂O₄(g) ⇌ 2NO₂(g)

Given the following sets of initial conditions, what is the net change that must occur for the reaction to reach equilibrium? Does the reaction shift left to reach equilibrium, does the reaction shift right to reach equilibrium or is the reaction at equilibrium at these initial concentrations so no net change will occur?

equilibrium, left, right? P_NO2 = 0.154 atm, P_N2O4 = 0.148 atm

equilibrium, left, right? P_NO2 = 0.210 atm, P_N2O4 = 0.138 atm

equilibrium, left, right ? P_NO2 = 0.149 atm, P_N2O4 = 0.05 atm

equilibrium, left, right? P_NO2 = 0.087 atm, P_N2O4 = 0.13 atm

equilibrium, left, right? P_NO2 = 0.068 atm, P_N2O4 = 0.058 atm

1. The Ostwald process is used commercially to produce nitric acid, which is, in turn, used in many modern chemical processes. In the first step of the Ostwald process, ammonia is reacted with oxygen gas to produce nitric oxide and water. What is the maximum mass of H2O that can be produced by combining 67.1 g of each reactant?

2. In the following reaction, how many grams of sodium sulfate, Na2SO4, will be produced from 80.7 g of sodium hydroxide, NaOH?

This problem is a long one, but fairly conceptual in nature.

a. For each of the following salts, write the reaction that occurs when it dissociates in water: NaCl(s), NaCN(s), KClO2(s), NH4NO3(s), KBr(aq), NaF(s).

b. Consider each of the reactions that you wrote above, and identify the aqueous ions that *could* be proton donors (acids) or proton acceptors (bases). Briefly *explain how you decided which ions to choose*.

c. For each of the acids and bases that you identified in part b, write the chemical reaction it can undergo in aqueous solution (its reaction with water).

d. Are there any reactions that you have written above that you anticipate will occur to such an extent that the pH of the solution will be affected? As part of your answer, be sure to explain how you decided.

e. Assume that in each case, above, 0.01 mol of the salt was dissolved in enough water at 25 deg Celsius to make 1.0L of solution. In each case, what additional information would you need in order to calculate the pH? If there are cases where no additional information is required, be sure to state that as well.

f. Say you take 0.01 mol of NH4CN and dissolve it in enough water at 25 deg Celsius to make 1.0L of solution. Using chemical reactions and words, explain how you would go about determining what effect this salt will have the pH of the solution. Be sure to list any additional information you would need to arrive at an answer.

Following are the post-lab questions for the experiment: Magnetic Behavior and Electron Configuration of Compounds Version

1. Chromium, Cr, has 24 electrons. Write out the entire electron configuration for chromium using spdf notation.

2. How many unpaired electrons would you expect for chromium in [Cr(H2O)6] 3+? Is this a paramagnetic or diamagnetic material?

3. Cobalt, Co, has 27 electrons. Write out the entire electron configuration for cobalt using spdf notation.

4. How many unpaired electrons would you expect for manganese in KMnO4? Is this a paramagnetic or diamagnetic material?

5. This same experiment is performed on the international space station. What is the primary issue with performing this experiment in the absence of gravity? Design an experiment to compensate for this. As always, you do have duct tape.

PART A:

Calculate pH for strong base solution: 7.4×10⁻² M KOH.

Express your answer using two decimal places.

PART B:

Calculate pH for strong base solution: 1.065 g of KOH in 510.0 mL of solution.

Express your answer using four decimal places

PART C:

Calculate pH for strong base solution: 15.0 mL of 1.90×10⁻² M Ca(OH)2 diluted to 510.0 mL.

Express your answer using three decimal places.