A 30.0-mL sample of 0.165 M propanoic acid is titrated with 0.300 MKOH.

A)Calculate the pH at 0 mL of added base. D)Calculate the pH at the equivalence point. G)Calculate the pH at 25 mL of added base.

B)Calculate the pH at 5 mL of added base. E)Calculate the pH at one-half of the equivalence point.

C)Calculate the pH at 10 mL of added base. F)Calculate the pH at 20 mL of added base.

Briefly explain Octahedral Crystal Field Splitting.

Oxidation-Reduction Titration

***Sulfuric acid used was 6 M

***All Lab notes are at the bottom, procedure included for clarity... PLEASE HELP WITH THE SHORT ANSWER:)

PROCEDURES:

Experiment 1: Prepare the Materials

Take four 100.00 mL volumetric flasks from the Containers shelf and place them on the workbench.

In one flask, prepare a standard solution of potassium dichromate (K₂Cr₂O₇):

Take potassium dichromate from the Materials shelf and add 4.00 g to the volumetric flask.

Take water from the Materials shelf and add 30.00 mL into the volumetric flask to dissolve the dichromate compound.

Complete the solution by filling the volumetric flask to the 100.00 mL mark with water from the Materials shelf by checking the "Fill To Mark" box.

Double-click on the volumetric flask to open a properties window. Then, rename the volumetric flask as "Standard Potassium Dichromate Solution".

In two of the empty flasks, prepare a standard solution of iron (II) ammonium sulfate hexahydrate (Fe(NH₄)₂(SO₄)₂ × 6H₂O):

Take iron(II) ammonium sulfate hexahydrate from the Materials shelf and add 4.00 g to each empty volumetric flask.

Take water from the Materials shelf and add 30.00 mL to each volumetric flask to dissolve the compound and release the water of hydration.

Complete both solutions by filling the volumetric flask to the 100.00 mL mark with water from the Materials shelf by checking the "Fill To Mark" box.

Rename the volumetric flasks as "Standard Iron(II) Solution". Both flasks will have the same name.

Take the Grey Moose vodka from the Materials shelf and add 2.00 mL to the last empty flask. Fill with water from the Materials shelf by checking the "Fill To Mark" box. The vodka has now been diluted to 1/50th, or 2%, of its original ethanol concentration.

Rename the volumetric flask containing the vodka as "2% Vodka Solution".

Experiment 2: Titrate the Vodka Sample

Part 1: Oxidize the Ethanol in Vodka

Take a 150.00 mL Erlenmeyer flask from the Containers shelf and place it on the workbench.

Add 5.00 mL of 2% vodka solution from the volumetric flask to the Erlenmeyer flask.

Take water from the Materials shelf and add 35.00 mL to the Erlenmeyer flask. Note that this further dilutes the vodka sample by a factor of eight. The ethanol concentration is now 1/8th of 2%, or 0.25% of the original ethanol concentration of the bottled vodka.

Acidify the vodka solution in the Erlenmeyer flask. Take the sulfuric acid (H₂SO₄) solution from the Materials shelf and add 5.00 mL to the Erlenmeyer flask.

Add 5.00 mL of the standard potassium dichromate solution from the volumetric flask to the Erlenmeyer flask. This is enough to reduce all of the ethanol in the vodka and leave an excess of dichromate ions. Note that the solution has turned bright green. This is the color of the reduced Cr³⁺ ions. Record these observations in your Lab Notes. Remember to press Save Notes each time you add more notes.

Part 2: Coarse Titration

Take a burette from the Containers shelf and place it on the workbench. Fill the burette with 50 mL of the standard iron(II) solution. Record the initial burette reading for the amount of volume dispensed in your Lab Notes. Before dispensing any liquid, the amount dispensed should read 0 mL.

Take the redox indicator, sodium diphenylamine sulfonate, from the Materials shelf and add 0.50 g to the Erlenmeyer flask. In the presence of the excess dichromate ions, the solution turns a deep purple.

Place the Erlenmeyer flask on the lower half of the burette to connect to flask and burette.

Perform a coarse titration by adding large increments of the standard iron(II) solution from the burette. To do this, press and hold the black knob at the bottom of the burette until the solution turns suddenly from intense, dark purple to green. Each time you add the standard iron(II) solution, check the volume dispensed from the burette by hovering over the burette and reading the gray tool tip. You will need to know this value.

As the iron(II) is added, the dichromate ions (Cr₂O₇^2–) are reduced to Cr³⁺ ions. At the end point of the titration, there are no dichromate ions left. The redox indicator becomes colorless, and the dark purple color suddenly disappears, leaving the solution bright green again. Recall that bright green is the color of the Cr³⁺ ions.

Record both the last burette volume that the solution was dark purple and the burette volume at which the solution first appeared green again in your Lab Notes. This gives the range in which the titration will end. Remember to press Save Notes.

Discard just the Erlenmeyer flask in the recycling bin underneath the workbench.

Part 3: Fine Titration

Set up the titration as before:

Add 5.00 mL of diluted vodka, 35.00 mL water, 5.00 mL of sulfuric acid, 5.00 mL of the standard potassium dichromate solution, and 0.50 g sodium diphenylamine sulfonate to an Erlenmeyer flask.

Connect the Erlenmeyer flask to the lower half of the burette.

Note the current volume of standard iron(II) solution in the burette. Add to it from the volumetric flask on the workbench so that the volume is 50.00 mL again. Record the initial burette reading for the amount dispensed in your Lab Notes.

Click and hold the black knob of the burette to quickly add enough standard iron(II) solution to just get into the range of the coarse titration (the first number you recorded), but still have the solution in the flask appear dark purple. This is near, but not yet at, the titration's end point.

Add standard iron(II) solution in small increments, down to one drop at a time, until the addition of just one more drop causes the solution in the flask to turn green. Record the final burette reading for the amount of volume dispensed in your Lab Notes.

Place the Erlenmeyer flask in the recycling bin beneath the workbench.

Repeat the fine titration once more, and record the results in your Lab Notes. If the results from the two fine titrations do not closely agree, perform a third fine titration to determine which of the first two was done incorrectly.   

SHORT ANSWER

Oxidation-Reduction Titration

Experiment 1: Prepare the Materials

Data Analysis

Calculate the concentration of the dichromate ion in the first volumetric flask.

Calculate the concentration of the iron (II) ion in the second volumetric flask.

Experiment 2: Titrate the Vodka Sample

Lab Results

Record the following lab data in the table below. If you had to repeat one of the titrations, disregard the value that was different.

Data Analysis

Record and calculate the quantities in the table below using the data from your dichromate titrations. Use an average value for the volume of iron (II) solution used in the titration. If one of your values is very different, and you had to perform the titration three times, disregard the value that was very different when computing the average.

  The amount of alcohol in a drink is typically reported as percent alcohol by volume. Volume percent or volume/volume percent (% v/v) most often is used when preparing solutions of liquids. Volume percent is defined as:
% v/v = V_solute/V_solution  × 100
Find the percent alcohol (ethanol) by volume for the vodka used in the lab by following the steps outlined in the table below.

Conclusions

The Grey Moose vodka tested in this lab reports a percent alcohol by volume of 40.0% on its label. How does your value compare to the reported one? If the values are different, give one possible experimental error that might have contributed to the difference.  

Potassium permanganate is another strong oxidizing substance similar to potassium dichromate. An acidic solution of purple permanganate ions can get reduced to colorless Mn²ions in the presence of ethanol. Write down the redox reaction between permanganate and ethanol, and balance it using the half-reaction method.

Besides vodka, there are other colorless alcohol-containing beverages that can be titrated following the procedure in your lab. Given the average values for the percent alcohol by volume listed in the table below, which beverage do you expect to use the least amount of iron (II) standard solution during the titration? Assume all lab procedures stay the same.

LAB NOTES:

Solution turned bright green upon adding the standard potassium dichromate.

Initial burette reading: 50 mL

(Solution turned deep purple after adding sodium diphenylamine sulfonate)

Coarse Titration:

First dispense

Volume: 46.93 mL

Volume dispensed: 3.07 mL

Second dispense

Volume: 44.07 mL

Volume dispensed: 5.93 mL

Third dispense

Volume: 40.91 mL

Volume dispensed: 9.09 mL

Fourth dispense

Volume: 37.74 mL

Volume dispensed: 12.26 mL

Fifth dispense- END POINT REACHED

Volume: 34.76 mL

Volume dispensed: 15.24 mL

Fine Titration 1

End point volume: 35.85 mL

Volume dispensed: 14.15 mL

Fine Titration 2:

End point volume: 35.86 mL

Volume dispensed: 14.14 mL

Mass of flask and foil (g) = 63.4842 Mass of flask, foil, and condesned vapor (g) = 63.6995 Temperature of boiling water bath (C) = 95 degrees C Volume of flask (mL) = 134 Barometric pressre (mmHg) = 763.8 Room temperature (C) = 21.0 degrees C Vapor pressure at room temperature (mmHg) = 100 Find the following: 1) Uncorrected mass of condensed vapor (g) = ? 2). Corrected density of air (g/L) = ? 3). Average volume of flask (L) = ? 4). Initial mass of air in flask (g) = ? 5) Final partial pressure of air in flask (mmHg) = ? 6). Final mass of air in flask (g) = ? 7). Mass of air lost (g) = ? 8). Corrected mass of condensed vapor (g) = ? 9) Molecular weight (g/mol) = ?

How many minutes will it take to plate out 16.22 g of aluminum metal from a solution of Al³⁺ using a current of 12.9 amps in an electrolytic cell?

At 1 atm, how much energy is required to heat 85.0 g of H2O(s) at –24.0 °C to H2O(g) at 135.0 °C? Helpful constants can be found here.

Calculate the pH of the solution after the addition of the following amounts of 0.0649 M HNO3 to a 70.0 mL solution of 0.0750 M aziridine. The pKa of aziridinium is 8.04.

a) 0.00 mL of HNO3

b) 7.30 mL of HNO3

c) Volume of HNO3 equal to half the quivalence point volume

d) 77.5 mL of HNO3

e) Volume of HNO3 equal to the equivalence point

f) 85.8 mL of HNO3

Please answer all parts of the question detailed with work. I will know if you are wrong, so please answer to the best of your ability.

Hint:

Aziridine (C2H5N), a weak base, reacts with a strong acid such as HNO3 to form its conjugate acid aziridinium (C2H5NH ). A strong acid reacts completely with a stoichiometric amount of weak base after each addition of the strong acid. In the titration of a weak base with a strong acid, there are four regions of the titration curve that require different calculations when determining the pH of the solution. 1) Before any strong acid is added to the solution. 2) Between the initial addition and the equivalence point. 3) At the equivalence point. 4) After the equivalence point.

The bond angle in NH₃ is significantly smaller than the ideal bond angle of 109.5° because of the lone pair on the central atom. Which best explains why the bond angle in SO₂ is very close to 120° despite there being a lone pair on the central atom?

Chemical equations serve a variety of purposes, but the most general form of a chemical equation is reactants -> products. Most often, reactants and products are described by their chemical formula, possibly including a designation of state of matter. Contrary to a general chemical equation, a balanced chemical equation always uses molecular formulas and is amended by stoichiometric factors to assure conservation of mass and/or moles.

Chemical equations represent chemical reactions, and chemical reactions can be classified according to two groups:

Group I (bond breakage and/or bond formation): The four reaction types are Synthesis, Decomposition, Single Displacement, Double Displacement.

Group II (common reaction principles): Representative examples are Precipitation, Redox, Acid-Base, Combustion. Choose from the following general chemical equations, and illustrate the four principle group I reaction types, and the four representative group II reaction types:

A) aqueous potassium sulfate + aqueous barium nitrate -> aqueous potassium nitrate + solid barium sulfate

B) magnesium metal + nitrogen gas -> solid magnesium nitride

C) copper metal + aqueous silver nitrate -> aqueous copper nitrate + silver metal

D) chlorine gas + fluorine gas -> chlorine monofluoride gas

E) aqueous hydrochloric acid + aqueous calcium hydroxide -> aqueous calcium chloride + water

F) gaseous sulfur dioxide + oxygen gas -> gaseous sulfur trioxide

G) solid calcium carbonate -> solid calcium oxide + gaseous carbon dioxide

H) solid silver oxide -> oxygen gas + silver metal

When you discuss reaction types, formulate the chosen general equation as balanced chemical equation.

Any given equation might serve as an example for a group I as well as for a group II reaction, but try to use as many different equations as possible.

a rock returned from the surface of the moon has a ratio of Rb⁸⁷ to stable Sr⁸⁷ atomos equal to 14.45 assuming that this was all Rb⁸⁷ upon the formation of the solar system, estimate the age of the solar system.

ans key:

t= 4.537*10^{9 yr}

11. If 0.0296 L of stock solution are diluted to 3.00L to form 0.345 M solution, what is the concentration of the stock solution?

56.0 mL of 2.50 M Fe(NO₃)₂ is combined with 25.0 mL of 0.0525 M Na₂CO₃.

K_sp of FeCO₃ is 2.1 × 10^-11.

What mass of FeCO₃(s) will be produced? in grams

What is the [Fe²⁺] in the solution final solution? in M

What is the [CO₃^2-] in the solution final solution? in M

An alkane with the formula C6H14 can be prepared by hydrogenation of either of only two precursor alkenes having the formula C6H12. Write the structure of this alkane, give its IUPAC name, and show the reactions. My confusion is to why the answer is not simply 2,3-hexene and the alkane is not hexane.