12. Calculate the pH of a buffer solution made from 0.30 M hydrofluoric acid and 0.70 M sodium fluoride after the addition of 0.08 mol of NaOH to 1.0 L of this solution.  Assume no change in volume.  The Ka for HF is 3.5 • 10-4.

Can someone guide me through this question? The answer is below but I can figure out how they got this answer.

Answer: pH = 4.01

To a 100.0mL volumetric flask are added 1.00 mL volumes of three solutions: 0.0100 M AgNO3, 0.190 M NaBr, and 0.100 M NaCN. The mixture is diluted with deionized water to the mark and shaken vigorously. What mass of AgBr would precipitate from this mixture? (Hint: The Ksp of AgBr is 5.4x10-13 and the Kf of Ag(CN)2- is 1.0x1021)

A 300mL buffer is prepared in which [HCO3-] = 0.2M and [CO3^2-]=0.075M.

a) What is the pH of this buffer (Ka HCO3-=4.7x10^-11)?

b) What is the pH of the buffer if 0.0100 moles of HCl are added?

c) What is the pH of the buffer if 0.0200 moles of NaOH are added?

Balance the following, in basic solution, by the method of half reactions.

C₂H₅OH +MnO₄^- -->C₂H₃O₂^- +MnO_2,

What is the coefficient on water (H₂O) in the product of the balanced equation?

Why can a heavy-water moderated reactor use a lower enrichment uranium fuel than a light water moderated reactor?

Structural data evolves with time, even for simple molecules. Consider the compounds E(CF₃)₃, i.e, the tris(trifluoromethyl) derivatives of P, As, and Sb. C-E-C bond angles were determined by gas-phase electron diffraction in the mid-20^th century and given as: E=P, 99.6°; E=As, 100.1°; E=Sb, 100.0°.          

a) Does this trend seem reasonable, and explain your answer.                    

b) A more rigorous recent similar experiment gave a C-As-C bond angle of 95.4°, compared to a calculated value of 95.9°. In view of this which of the other two C-E-C bond angles seems most suspect, and why?

What is the lead (II) ion concentration in a solution prepared by mixing 341 mL of 0.363 M lead (II) nitrate with 379 mL of 0.359 M sodium fluoride? The Ksp of lead (II) fluoride is 3.6 × 10-8?

Part C - Describe how a white light source could be engineered using CdSe quantum dots.

A 35.0-mL sample of 0.150 M acetic acid (CH3COOH) is titrated with 0.150 MNaOHsolution. Calculate the pH after the following volumes of base have been added.

35.5 mL

Express your answer using two decimal places.

Answer the following questions:

a). The heat of fusion of ice is 6.00 kJ/mol. Find the number of photons of wavelength = 6.27 10-6 m that must be absorbed to melt 3.00 g of ice

b). The energy required to ionize potassium is 419 kJ/mol. What minimum frequency of light is required to ionize potassium?

c). An X-ray photon of wavelength 0.920 nm strikes a surface. The emitted electron has a kinetic energy of 936 eV. What is the binding energy of the electron in kJ/mol? [KE = .5 mv2; 1 electron volt (eV) = 1.602 10-19 J]

Hexokinase catalyzes the first step of glycolysis, in which glucose is phosphorylated to form glucose-6-phosphate. Which of the following statements are accurate? Choose all that apply.

Hexokinase is found in the mitochondrial membrane.

Hexokinase consists of two domains, or lobes, that come together when glucose and the MgATP2� complex are bound.

Most kinases require the presence of a monovalent metal ion cofactor to prevent ATP hydrolysis.

The conformational shift that occurs when glucose, but not water, enters the active site prevents water from hydrolyzing ATP.

Hexokinase transfers the terminal phosphate of ATP to carbon 3 of glucose.

Hexokinase is a type of transferase that catalyzes the transfer of a phosphoryl group from ATP to a hexose.

I already answered the first three questions and put the answer down I just don't know how to answer the last question which asks to calculate K in the rate law?

A clock reaction is run at 20 ºC with several different mixtures of iodide, sodium bromate and acid, to form iodine. Thiosulfate is used to react with the iodine formed initially. Starch indicator is added to form a blue color when all the thiosulfate has been used up and the iodine concentration begins to rise. The following sets of mixtures are used.

Initial concentrations in reaction mixtures
Run number [I^-]      [BrO₃^-]      [H⁺]
1 0.002          0.008       0.02
2 0.002       0.016            0.02
3 0.004         0.008         0.02
4 0.002        0.008             0.04   
[S₂O₃^2- ] is equal to 0.0001M in each reaction mixture.
The rate law is :
  
Rate = k [ I^-]^a   [ BrO₃^-]^b   [H⁺]^c


Reaction time in run number 1 30
Reaction time in run number 2 30
Reaction time in run number 3 15
Reaction time in run number 4 30

Calculate the following
a in the rate law

a=1

A clock reaction is run at 20 ºC with several different mixtures of iodide, sodium bromate and acid, to form iodine. Thiosulfate is used to react with the iodine formed initially. Starch indicator is added to form a blue color when all the thiosulfate has been used up and the iodine concentration begins to rise. The following sets of mixtures are used.

Initial concentrations in reaction mixtures
Run number [I^-]      [BrO₃^-]      [H⁺]
1 0.002          0.008       0.02
2 0.002       0.016            0.02
3 0.004         0.008         0.02
4 0.002        0.008             0.04   
[S₂O₃^2- ] is equal to 0.0001M in each reaction mixture.
The rate law is :
  
Rate = k [ I^-]^a   [ BrO₃^-]^b   [H⁺]^c


Reaction time in run number 1 30
Reaction time in run number 2 30
Reaction time in run number 3 15
Reaction time in run number 4 30

Calculate the following
b in the rate law

b=0

A clock reaction is run at 20 ºC with several different mixtures of iodide, sodium bromate and acid, to form iodine. Thiosulfate is used to react with the iodine formed initially. Starch indicator is added to form a blue color when all the thiosulfate has been used up and the iodine concentration begins to rise. The following sets of mixtures are used.

Initial concentrations in reaction mixtures
Run number [I^-]      [BrO₃^-]      [H⁺]
1 0.002          0.008       0.02
2 0.002       0.016            0.02
3 0.004         0.008         0.02
4 0.002        0.008             0.04   
[S₂O₃^2- ] is equal to 0.0001M in each reaction mixture.
The rate law is :
  
Rate = k [ I^-]^a   [ BrO₃^-]^b   [H⁺]^c


Reaction time in run number 1 30
Reaction time in run number 2 30
Reaction time in run number 3 15
Reaction time in run number 4 30

Calculate the following
c in the rate law

C=0

If the rate law for the clock reaction is:

   
Rate = k [ I^-] [ BrO₃^-] [H⁺]

A clock reaction is run with the following initial concentrations:

[I^-]               [BrO₃^-]            [H⁺]                         [S₂O₃^2-]
0.002                   0.008                   0.02                          0.0001  

The reaction time is 28 seconds

Calculate k in the rate law:?

You are making a stock salt solution by diluting 0.7563g of salt to 500mL with water.

a) What is the analytical concentration (in mol/L) if the salt is sodium chloride?

b) What is the analytical concentration of the solution (in mol/L) if the salt is Mohr's Salt?

c) How would you prepare 0.5L of -2x10^-4 M and -4x10^-5 M solutions from your Mohr's stock solution? Round to reasonable aliquot sizes, keeping in mind common pipette volumes.

d) Convert the concentrations in c. to ppm. Assume the density of the solution is that of the pure solvent.

d)

At 800K, 2 mol of NO are mixed with 1 mol of O2. The reaction 2NO(g) + O2(g) <---> 2NO2(g) comes to equilibrium under a total pressure of 1 atm. Analysis of the system shows that 0.71 mol of oxygen are present at equilibrium.

Calculate the equilibrium constant for the reaction.

answers 0.64