Given:

Ka1= 7.5*10^-3

Ka2=6.2*10^-8

Ka3=4.2*10^-13

What is the pH of a solution of 0.550 M K2HPO4, potassium hydrogen phosphate?

What is the pH of a solution of 0.400 M KH2PO4, potassium dihydrogen phosphate?

calculate the formula mass of each compound given below. keep at least one decimal place in atomic masses from the periodic table. a) hydrogen peroxide, H2O2. b) sulfuric acid, H2SO4.

Calculate the change in entropy when 108 ml of hot (97 oC) water added to 36 ml cold (5 oC) water in a closed Styrofoam cup given that C_p (H₂O, l) = 75.5 J/(mol * K)

200. g of liquid phase octane (C8H18) are burned in air at a temperature of 100. degrees Celsius and a pressure of 1.00 atm, forming vapor phase water and carbon dioxide.

a) Write the balanced chemical reaction equation for this process.

b) What is the magnitude of the difference between ΔE and ΔH for one mole of octane going through this process? (Hint: use the value of R that makes life easiest.)

c) The reaction is in contact with a reservoir of water that is also at 100 degrees Celsius. If that reservoir absorbs all of the heat released by the reaction (of the 200. g of octane), how many moles of the water will evaporate? Each mole of C8H18 releases 5074.482 kJ of heat when it goes through this process.

Part a I got no problem, but I can't seem to figure out parts b and c. Thanks for the help!!

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Hi, I am doing an experiment that is called NaBH4 reduction of acetophenone. I am having trouble understand the techinque/wording when using a sep funnel. These are some of the procedures below:

1. Pour the mixture into a separatory funnel and add 20 mL of ice water. Rinse the beaker with additional ice water (5 mL) and add the rinsing to the separatory funnel. Rinise the beaker with ether (2 X 15 mL), adding the ether to the separatory funnel.

2. shake mixture, vent, and then remove the ether layer and set aside. Most of the product should be in the ether layer

3. extract the aqueous layer with ether (2 x 25 mL) to remove the remainder of the product. Combine all ether layers in a common beaker

(The multiply sign means the number of times you do it)---however can someone explain to me more clearly of that the steps tell you to do?

Consider the reaction between oxalate ion and permanganate ion in acidic solution: ???4 − (??) + ?2?4 2−(??) → ??2+(??) + ??2 (?)

a. Balance the reaction in acidic solution

b. Determine the standard cell potential of the representative voltaic cell

c. Determine the standard free energy change of this reaction

d. Determine the cell potential if the pH = 4 and all other solute concentrations were standard.

Using data found in Appendix E of your textbook calculate the nonstandard emf for each of the following reactions if the concentration of each of the ions in these reactions is 0.0006 molar and everything else is standard (use 298 K for the temperature, R = 8.314 J/mol-K, and F = 96,485 C/mol):

(a) 1 Cl2(g) + 1 Ca(s) --> 2 Cl-(aq) + 1 Ca2+(aq) E = ___V

b) 2 Cu2+(aq) + 1 Fe(s) --> 2 Cu+(aq) + 1 Fe2+(aq) E = ___V

(c) 1 Hg22+(aq) + 2 Cu(s) --> 2 Hg(l) + 2 Cu+(aq) E =___ V

(d) 1 Cd2+(aq) + 1 Sn(s) --> 1 Cd(s) + 1 Sn2+(aq) E = ___V

One kmol of gaseous octane (C8H18) is ignited with stoichiometric amount of dry air in a closed, rigid vessel. The pressure of the reactants is 1 atm and the temperature is 25C; while the temperature of the products is 727C. Assume “complete” combustion.

(a) Calculate the pressure (atm) of the products.

(b) Determine the heat transfer (kJ/kg fuel) during the reaction.

Answer: (a) 3.42 atm

Two enterprising chemistry students decide to develop an alternative to Alka-Seltzer tablets, replacing the aspirin (acetylsalicylic acid) with vitamin c (ascorbic acid). The following table shows one of the formulations they tried for a 5 g tablet.

When the tablet dissolves in water, it "frizzes" as the bicarbonate reacts with the citric acid and the vitamin C. What mass of NaHCO₃ reacts with the vitamin C?

Citric acid is triprotic, and reacts with the base to form the citrate ino (C₆H₅O₇^3-). Write the overall ionic reaction for the acidification of the NaHCO₃ by the citric acid, giving CO₂ as the product. Citric acid should be written as H₃C₆H₅O₇ in the net ionic equation, as weak acids are written in the molecular form even though they slightly ionize.

What mass of the NaHCO₃ reacts with the citric acid?

What is the mass of CO₂ released in this reaction?

THe remaining NaHCO₃ is available to neautralize stomach acid. What mass of stomach HCL could be neutralized by one tablet?

Under what geochemical conditions is uranium soluble in water as an ion with 6+ charge? [Select ALL answers that apply]

Write net Bronsted equations and determine the equilibrium constants for the acid-base reactions that occur when aqueous solutions of the following are mixed. Instructions: Enter all substances in the order listed at the top of the column.

Use a carot to indicate a superscript, but do nothing for subscripts.

Use a hyphen + greater than (->) for yields. Click on the eye symbol to check your formatting.

Report K to three sig figs even though it is good to only two. Group 1A and 7A ions (except fluoride) are spectator ions.

A) hydrofluoric acid + potassium cyanide

B) perchloric acid + sodium cyanide

C) formic acid (HCHO₂) + sodium nitrite

D) KHSO₄ + NH₃

E) H₂S + KClO

A 100.0 mL solution containing 0.753 g of maleic acid (MW = 116.072 g/mol) is titrated with 0.259 M KOH. Calculate the pH of the solution after the addition of 50.0 mL of the KOH solution. Maleic acid has pKa values of 1.92 and 6.27.

At this pH, calculate the concentration of each form of maleic acid in the solution at equilibrium. The three forms of maleic acid are abbreviated H2M, HM–, and M2–, which represent the fully protonated, intermediate, and fully deprotonated forms, respectively.

A 39.7g piece of copper rod is heated to 98 degrees celsius and then placed in an insulated container containing 50.7 grams of water at 18.3 degrees celsius. Assuming no loss of water and using the following parameters, what is the final temperature of the system? Assume that the container is always at the same temperature as that of the water.

C_copper 0.387(J/gxK) C_H2O 4.184(J/gxK) C_vessel 12.30 (J/K)

Describe how the solutions used in standard calibration curves differ from those used in a standard addition curve?

Describe how the concentration of an unknown analyte is found from a standard addition curve?

Why is distilled water used as a calibration blank?