You are asked to prepare a buffer solution of H₂PO₄^-/HPO₄^2- with a pH of 6.68. A 153.00 mL solution already contains 0.126 M HPO₄^2-.

Hint: you will need to look up the proper K_a in your textbook

How many grams of NaH₂PO₄ must be added to achieve the desired pH? You may assume that the volume change upon salt addition is negligible. in g

1. The degree to which a weak base dissociates is given by the base-ionization constant, Kb. For the generic weak base, B B(aq)+H2O(l)⇌BH+(aq)+OH−(aq) this constant is given by Kb=[BH+][OH−][B] Strong bases will have a higher Kb value. Similarly, strong bases will have a higher percent ionization value. Percent ionization=[OH−] equilibrium[B] initial×100% Strong bases, for which Kb is very large, ionize completely (100%). For weak bases, the percent ionization changes with concentration. The more dilute the solution, the greater the percent ionization. Ammonia, NH3, is a weak base with a Kb value of 1.8×10−5.

partA What is the pH of a 0.245 M ammonia solution?

partB What is the percent ionization of ammonia at this concentration?

2. To understand the relation between the strength of an acid or a base and its pKa and pKb values. The degree to which a weak acid dissociates in solution is given by its acid-ionization constant, Ka. For the generic weak acid, HA, HA(aq)⇌A−(aq)+H+(aq) and the acid-ionization constant is given by Ka=[A−][H+][HA] Similarly, the degree to which a weak base reacts with H2O in solution is given by its base-ionization constant, Kb. For the generic weak base, B, B(aq)+H2O(l)⇌BH+(aq)+OH−(aq) and the base-ionization constant is given by Kb=[BH+][OH−][B]

Another way to express acid strength is by using pKa: pKa=−logKa Another way to express base strength is by using pKb: pKb=−logKb

partA: A new potential heart medicine, code-named X-281, is being tested by a pharmaceutical company, Pharma-pill. As a research technician at Pharma-pill, you are told that X-281 is a monoprotic weak acid, but because of security concerns, the actual chemical formula must remain top secret. The company is interested in the drug's Ka value because only the dissociated form of the chemical is active in preventing cholesterol buildup in arteries. To find the pKa of X-281, you prepare a 0.086 M test solution of X-281 at 25.0 ∘C. The pH of the solution is determined to be 2.40. What is the pKa of X-281? pKa=?

3. Classify each salt as acidic, basic, or neutral. (KBr, NaNO2, AlCl3)

4. Rank the following compounds in order of decreasing acid strength using periodic trends. strongest acid to weakest acid (MgH2, HI, HBr, H2Se)

a. normal boiling point of a solution made from 18.02 g glucose dissolved in 1.250 kg of water b. normal freezing point of a solution made from 180.2 g glucose dissolved in 1250 g of water c. normal freezing point predicted for a solution made from 58.44 g sodium chloride dissolved in 250.0 g of water d. osmotic pressure predicted for a solution made from 5.844 g sodium chloride dissolved in 2000.0 mL of water at 25.0 0 C e. vapor pressure above a solution made from 180.2 g glucose dissolved in 180.2 g of water at 100.0 0 C and normal pressure

A---Write a net ionic equation to show that ethylamine, C₂H₅NH₂, behaves as a Bronsted-Lowry base in water.
-----Write a net ionic equation to show that codeine, C₁₈H₂₁O₃N, behaves as a Bronsted-Lowry base in water.
-----Write a net ionic equation to show that hydrofluoric acid behaves as a Brønsted-Lowry acid in water.

B---Write the K_a expression for an aqueous solution of acetic acid:

----Write the K_a expression for an aqueous solution of hydrofluoric acid:

----Write the K_a expression for an aqueous solution of hypochlorous acid:

C---In the laboratory, a general chemistry student measured the pH of a 0.402 M aqueous solution of formic acid, HCOOH to be 2.054.
Use the information she obtained to determine the K_a for this acid

-----In the laboratory, a general chemistry student measured the pH of a 0.402 M aqueous solution of acetic acid to be 2.587.

Use the information she obtained to determine the K_a for this acid.

----In the laboratory, a general chemistry student measured the pH of a 0.402 M aqueous solution of hydrofluoric acid to be 1.753.
Use the information she obtained to determine the K_a for this acid.

A solution of the sugar mannitol (mol wt 182.2) is prepared by adding 54.66g of mannitol to 1000g of water. The vapor pressure of pure liquid water is 2338 Pa at 20⁰C. Mannitol is nonvolatile and does not ionize in aqueous solutions.

a. Assuming that aqueous mannitol solutions behave ideally, calculate the vapor pressure lowering (the difference between the vapor pressure of pure water and that of the solution) for the above solution at 20⁰C.

b. The observed vapor pressure lowering of the mannitol solution above is 12.40Pa. Calculate the activity coefficient (based on mole fraction) of water in this solution.

c. Calculate the osmotic pressure of the mannitol solution of part (b) when it is measured against pure water and compare it with the osmotic pressure of the ideal solution.

A solution of the sugar mannitol (mol wt 182.2) is prepared by adding 54.66g of mannitol to 1000g of water. The vapor pressure of pure liquid water is 2338 Pa at 20⁰C. Mannitol is nonvolatile and does not ionize in aqueous solutions.

a. Assuming that aqueous mannitol solutions behave ideally, calculate the vapor pressure lowering (the difference between the vapor pressure of pure water and that of the solution) for the above solution at 20⁰C.

b. The observed vapor pressure lowering of the mannitol solution above is 12.40Pa. Calculate the activity coefficient (based on mole fraction) of water in this solution.

c. Calculate the osmotic pressure of the mannitol solution of part (b) when it is measured against pure water and compare it with the osmotic pressure of the ideal solution.

How do heat treatments affect the hardness and impact properties (microstructure)?

Draw the reaction mechanism that shows BH3 adding to the alkene. Why do we get the anti-Markovnikov product?

Which of the following represent a valid set of quantum numbers?
n = 1, l = 0, ml = -1, ms = +1/2
n = 3, l = 2, ml = -2, ms = -1/2
n = 2, l = 2, ml = -1, ms = +1/2
n = 2, l = 1, ml = 0, ms = 0
n = 2, l = 1, ml = 0, ms = -1/2

Show that in a cubic crystal [HKL] direction is always perpendicular to a plane whose Miller indices are (HKL). Show the general proof and not example of specific plane and direction.

1. Show the reaction, along with the transition state (‡), between 2-methyl-2-pentene and BH3 in THF. Then, show the subsequent reaction of the organoborane intermediate with H2O2 and OH-1. Explain why hydroboration is non-Markovnikov and forms a 2o alcohol. Refer to hydroboration in the chapter notes, the handout for example 8.2, and figure 8.4 in text. (2 pts)

Using Stoichiometry,calculate the mole quantity of hydrogen gas produced for each data point in Part A and Part B of this experiment using your data. Identify the concentration of HCl (part A) or mass of magnesium (part B)for when the limiting reactant changes. All calculations must be shown.

Part A

1. )0.250 g Mg

2. )0.50 M

3. )1.0 M

4. )1.5 M

5.) 2.0 M

6.) 2.5 M

7.) 3.0 M

8.) 3.5 M

PART B

1. 2.0 M HCl -Entre moles of calculated moles of H2 (g) from Part A.

2. 0.050 g

3. 0.10 g

4. 0.15 g

5. 0.20 g

6. 0.25 g -enter moles of calculated moles of H2 (g) from Part A.

7. 0.30 g

8. 0.35 g

9. 0.40 g

http://tinypic.com/r/kah0rt/9 Here is the data page. I hope the data page is legible!

PLEASE HELP! Even if you could just explain the process for just one of them that would be helpful. I assume once you get the first one the other ones should follow the same method of solving. I would really appreciate anyone's help as soon as possible.

A gas has a volume of 4.70 L at 0 ∘C. What final temperature, in degrees Celsius, is needed to change the volume of the gas to each of the following, if n and P do not change?

a) 1.60 L

b) 1800 mL

c) 51.0 mL

Given:

AgBr_(s) <--> Ag⁺_(aq) + Br ^-_(aq)

and

Ag⁺_(aq) + 2NH_3(aq) <--> Ag(NH₃)₂⁺_(aq)

a) What would be the value of K for AgBr_(s) + 2NH₃(aq) <--> Ag(NH₃)₂⁺_(aq) + Br ^-_(aq) ?

b) What would be the molar solubility of silver bromide in 2.00 M aqueous ammonia?

A 0.1276−g sample of a monoprotic acid (molar mass = 1.10 × 102 g/mol) was dissolved in 25.0 mL of water and titrated with 0.0633 M NaOH. After 10.0 mL of base had been added, the pH was determined to be 4.87. What is the Ka for the acid? Answer in scientific notation.