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18 Nov 2019

Everytime I make the graph based off my calculations in the chart it looks like this and I have no idea if it is even close? Please help ! For the questions I just need to understand how to start them and what info is nessiary to do so. very confused.

Data Analysis

Fill in the following table. Look below the table for instructions on how to calculate the values for each row of the table.

a total volume (L) 0.065L
b mol S2O32-consumed 0.010 mol
c mol I3-produced 0.015M
d [S2O32-] consumed (M) 0.154M
e [I3-] produced (M) 0.231M

Calculate the final volume of the reaction mixture after the contents of beaker B are added to beaker A. Report your answer in liters.

All S2O32- is consumed at the end of the reaction. Therefore, the moles of S2O32- consumed can be calculated using the equation below.
(moles S2O32-)consumed = Mstock x (Vstock)

The I3- produced in reaction 1 reacts with S2O32- in reaction 2 as shown.
I3- (aq) 2S2O32- (aq) → 3I- (aq) S4O62- (aq)

Therefore, for every mole of I3- produced, 2 moles of S2O32- have reacted.
(moles I3-)produced = (moles S2O32-)consumed / 2

[S2O32-]consumed = (moles S2O32-)consumed / (Vtotal)

Calculation is the same as d, but using I3- instead of S2O32-.

Fill in the following table. Look below the table for instructions on how to calculate the values for each column of the table.

a b c d e f g h i
Trial Δt Δ[I3-] / Δt (M/s) log(Δ[I3-] / Δt) V 0.2 M KI added (mL) [I–]0(M) log[I–]0 V of 0.2 M (NH4)S2O8 (mL) [S2O8]0 (M) log[S2O8]0
1 19 .011 -1.94 25 .077 -1.35 25 .077 -1.11
2 40 .0055 -2.24 25 .077 -1.11 12.5 .038 -1.42
3 85 .0030 -1.84 25 .077 -.1.11 6.25 .019 -1.72
4 42 .0055 -2.26 12.5 .038 -1.42 25 .077 -1.11

Conclusions

If a large amount of heat was released at the start of the reaction, what effect would this have on the rate measurements?

The rate of reaction would be much slower due to its exothermic reaction properties.

Click the box underneath the graph to show the trendline. It will automatically calculate your slope and intercept. Record them below.

Determine the value of q from the graph. Explain your answer.

What is the rate law for the reaction?

For each trial, calculate the rate constant. What is average value of the rate constant?

In this experiment, you assumed that [S2O82–] >> [S2O32–]. To find out if this assumption is correct, calculate the ratio of [S2O82–] / [S2O32–] for Trial 3. (In Trial 3, the [S2O82–] was lowest, and therefore the ratio [S2O82–] / [S2O32–] is the smallest).

In this experiment, you assumed that only a small amount of S2O82– was used during the time trial so that the concentration of this reactant did not change appreciably during the course of the reaction. Calculate how much S2O82– was used in Trial 3 and the percent remaining at the end of the reaction. Was this assumption valid?

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Related questions

Chemical Kenetics

Trial 1

Flask A

25ml of 0.2 M Potassium Iodide (ml) and Volume of 0.2% starch(ml) were added together,

Flask B

25 ml of volume 0.2M Ammonium Persulfate and volume of 0.01 M sodium Thiosulfate(ml) were added together,

After adding flask A and B together, after 20 sec the solution turned from clear to black.

Trial 2

Flask A

25ml of 0.2 M Potassium Iodide (ml) and Volume of 0.2% starch(ml) were added together,

Flask B

12.5ml of 0.2 M Ammonium Persulfate, 12.5ml of 0.2 M Ammonium Sulfate(ml), 10 ml of 0.01 M Sodium Thiosulfate(ml) were added together,

When flask A and B were added, after 42 sec, it turned from clear to black.

Trial 3

Flask A

25ml of 0.2 M Potassium Iodide (ml) and Volume of 0.2% starch(ml) were added together,

Flask B

6.25ml of 0.2 M Ammonium Persulfate (ml), 18.75ml of 0.2 M Ammonium Sulfate, and 10ml of 0.01 M sodium Thiosulfate (ml) were added together.

After flask A and B were added together, at a min and 26 sec, it turned from clear to black.

Trial 4

Flask A

12.5ml of 0.2 M Potassium Iodide (ml), 12.5ml of 0.2 M Potassium Nitrate (ml), 5 ml of 0.2% starch were added together,

Flask B

25 ml of 0.2 Ammonium Persulfate, 10ml of 0.01 M Sodium Thiosulfate (ml) were added together

after mixing both A and B together, at 42 seconds, it turned clear to black.

Trial 5

Flask A

6.25ml of 0.2 M Potassium Iodide, 18.75 ml of 0.2 M Potassium Nitrate, 5ml of 0.2% starch were added together.

Flask B

25 ml of 0.2 Ammonium Persulfate, 10ml of 0.01 M Sodium Thiosulfate (ml) were added together,

After adding flask A and B together, after 1 min and 28 sec, it turned from clear to black.

All at the temp 21.5 C

Questions,

1.What was the initial concentration of thiosulfate?

A.0.00165 M

B.0.00154 M

C.0.00077 M

D.0.00134 M

2. What was the rate of reaction in Trial 1? Choose the closest answer.

A.3.13 x 10-5 M s-1

B.3.85 x 10-5 M s-1

C.4.15 x 10-5 M s-1

D.3.99 x 10-5 M s-1

3. What was the concentration of peroxodisulfate in Trial 1?

A.0.0569 M

B.0.0769 M

C.0.0669 M

D.0.0879 M

4. What was the concentration of iodide in Trial 1?

A.0.0769 M

B. 0.0659 M

C. 0.0869 M

D.0.0571 M

5. What is the order of peroxodisulfate in the rate expression?

A.0

B.2

C.1.5

D.1

6. What is the order of iodide in the rate expression?

A.0

B.2

C.1

D.3

7. What is the rate law for this reaction?

A.rate = k[I-]3[S2O82-]

B.rate = k[I-]2[S2O82-]

C.rate = k[I-][S2O82-]

D.rate = k[I-]1.5[S2O82-]

8. What is the average rate constant? Choose the closest answer.

A.5.44 x 10-3 L/(mol s)

B.5.73 x 10-3 L/(mol s)

C.6.88 x 10-3 L/(mol s)

D.6.16 x 10-3 L/(mol s)

9. The following reaction is second order with respect to A and zero order with respect to B. Identify the correct rate expression.

2A + B -> C + 2D

A.rate = k[A]4

B.rate = k[2A]2

C.rate = k[A]2

D.rate = k[A]2[B]

10. What is the overall reaction order for a reaction with the following rate expression?

rate = k[A]2[B]

A.3

B.1

C.2

D.4

11.A plot of log(rate) versus log[A] yields the following linear equation. What order is the reaction with respect to A?

y = 1.9x + 3.1

A.5

B.2

C.3

D.1.5

12. The iodine clock experiment, which consists of the following three reactions, is set up so [S2O32-] < [S2O82-]. What would happen if [S2O32-] > [S2O82-]?

Reaction 1: 3I- (aq) + S2O82- (aq) ->I3- (aq) + 2SO42- (aq) slow

Reaction 2: I3- (aq) + 2S2O32- (aq) -> 3I- (aq) + S4O62- (aq) fast

Reaction 3: I3- (aq) + starch (aq) -> 3I- ---- starch (bluish black) fast

A.No bluish black color would form because all the I- formed in reaction 1 would be converted back into I3-.

B.The bluish black color would be darker because more S2O32- is present.

C.The bluish black color would be darker because more S2O32- is present.

D.No bluish black color would form because all the I3- formed in reaction 1 would be converted back into I-.

13. The iodine clock experiment consists of the following three reactions, where reaction 1 is slow relative to reactions 2 and 3. Predict what would happen if reaction 2 was slow relative to reaction 1 (assume that reaction 3 is still fast).

Reaction 1: 3I- (aq) + S2O82- (aq) -> I3- (aq) + 2SO42- (aq) slow
Reaction 2: I3- (aq) + 2S2O32- (aq) -> 3I- (aq) + S4O62- (aq) fast
Reaction 3: I3- (aq) + starch (aq) -> 3I- ---- starch (bluish black) fast

A.The reaction would turn blue slower because I3- is removed at a slower rate.

B.A color change would appear immediately because I3- would be removed slowly from solution, and would therefore be able to react with starch.

C.The rate of color change would indicate the rate of reaction 3 instead of reaction 1.

D.Reaction 3 would not occur.

14. A student conducting the iodine clock experiment accidentally makes an S2O32- stock solution that is too concentrated. How will this affect the rate measurement?

Reaction 1: 3I- (aq) + S2O82- (aq) -> I3- (aq) + 2SO42- (aq) slow
Reaction 2: I3- (aq) + 2S2O32- (aq) -> 3I- (aq) + S4O62- (aq) fast
Reaction 3: I3- (aq) + starch (aq) -> 3I- ---- starch (bluish black) fast

A.It will take less time for the color to change, which will decrease delta t, resulting in a higher calculated rate.

B.It will take longer for the color to change, which will increase delta t, resulting in a lower calculated rate.

C.It will take less time for the color to change, which will increase delta t, resulting in a lower calculated rate.

D.It will take longer for the color to change, which will increase delta t, resulting in a higher calculated rate.

15. A student conducting the iodine clock experiment accidentally makes an S2O82- stock solution that is too concentrated. How will this affect the rate measurement?

Reaction 1: 3I- (aq) + S2O82- (aq) -> I3- (aq) + 2SO42- (aq) slow
Reaction 2: I3- (aq) + 2S2O32- (aq) -> 3I- (aq) + S4O62- (aq) fast
Reaction 3: I3- (aq) + starch (aq) -> 3I- ---- starch (bluish black) fast

A.Not all of the 2S2O32- will react, which will decrease the calculated rate.

B.Not all of the 2S2O32- will react, which will increase the calculated rate.

C.It will take longer for the color to change, as the reaction takes longer when more reactant is present.

D.It will take less time for the color to change, as rate increases with concentration of reactant.

16. The following reaction is first order. If the rate at [A] = 0.1 M is 3, what will the rate be at [A] = 0.2 M?

A -> B + C

A.4

B.6

C.9

D.3

17. For a zero order reaction, if the concentration of reactant is increased 4-fold, the reaction rate

A.increases four-fold.

B.increases 8-fold.

C.increases 16-fold.

D.remains the same.

18. If 2.3 x 10-3 M product forms in 46 seconds, what is the rate of the reaction?

A.50 M/s

B.2.3 x 10-3 M/s

C.5.0 x 10-5 M/s

D.2.0 x 104 M/s

19. A plot of log(delta [I3-] / delta t) versus log [I-]0 from data in Trials 1, 4, and 5 is shown below. Determine the value of p from the graph.


A.1

B.0.5

C.2

D.1.5

I know I am only supposed to post one question per answer, but I feel they all go into one, and that is alot of repitition, Anything helps, I need calculations to help me learn it, I have many more questions but I feel if I get some, and get a understanding on how to calculate it, then I will be able to do the rest. Thank you so much.

Equipment Materials

50.00 ml buret, 250.ml volumetric flask, 1.00 ml volumetric pipet 10.0 mL volumetric pipet, 25.00 mL volumetric pipet, pipettor, 250 mL Erlenmeyer flask, 10.0 mL graduated cylinder, several beakers, several watchglasses, unkown bleach solution, 10% potassium iodide solution, 2M hydrochloric acid solution, 0.150 M sodium thiosulfate solution, 1% starch solution.

Background information regarding this experiment is as follows:

An aqueous solution of sodium hypochlorite (NaOCI) is a clear, slightly yellow liquid, and is commonly known as bleach. Aside from its uses as a bleaching agent, sodium hypochlorite solutions are also used as sterlizing agents and in water treatment. Industrial uses include agricultural, food handling, paper production, and textile production. Sodium hypochlorite is also added to waste water to reduce odors.

The concentration of sodium hypochlorite in bleach solutions can be determined by titration. Therefore, we must use a two-step method to titrate sodium hypochlorite. In the first step, sodium hypochlortie, hydrochloric acid, iodide ion, and starch are combined to form a starch-triiodide complex. In this step there are 3 reactions that take place:

The result of these 3 reactions is that when sodium hypochlorite is present the starch-triiodide complex is produced.

In the second step the starch-triiodide product is titrated by sodium thiosulfate to form a colorless solution of iodide, dithionate.

I do not know how to answer the following on the data sheet: (? means I do not know how to answer)

Table 1:

Mass of 1.00 ml of unknown (by tare): 10.552 g

Density of bleach: (g/ml) : 1.055 g/ml

Volume of diluted bleach used in each titration: 10.00

Concentration of sodium thiosulfate: ? (M)

Titration Data:

Initial buret reading (ml): trial1: 0.000 ml Trial 2: 0.00 ml Trial 3: 0.000ml

Final buret reading (ml): trial 1: 13.50ml Trial 2: 13.30ml Trial 3: 13.40ml

Volume delivered(ml: trial 1: ? Trial 2: ? trial 3:?

Calculations: (show clearly)

For trial 1,2,3 ???

1.Moles of Na2S2O3 in titration: ??? trial 1,2,3

2.Moles of NaOCl: ???trial 1, 2,3

3.Average moles of diluted NaOCl: (one answer) ?

4.Average moles of undiluted NaOCl: (one answer.. mol) ?

5.Standard Deviation: (one answer) (mol)

6.Average mass of NaOCl in 25.00mL of undiluted bleach: ? (g)

7.mass of 25.00 mL of undiluted bleach: ? (g)

8. Mass % of NaOCL from experiment: ? (%)

9.Actual mass % of NaOCL (from prof; student does not make an entry):? (%)

More questions all need to be answered please:

1. Calculate the volume of the reagent thiosulafte solution which would be required if you titrated a 25ml sample of the original commercial bleach instead of 25ml of the diluted solution.

2. Why would we choose a graduated cylinder to measure the HCl and KI solutions instead of a volumetric pipette? When would we use a volumetric pippette?

3. You calculated the mass percent of sodium hypochlorite in the bleach( dilute and undiluted). Now calculate the molarity of the sodium hypochlorite in the diulte and undiluted solution/

4. Use oxidation states to show that equations (2) and (4) in the introduction are redox reactions and that equation 1 is not a redox reaction. :

-(1) NaOCl(aq) + HCl(aq) yields HOCl(aq)+NaCl(aq)

-(2) HOCL (aq) + HCl(aq) + 3I(aq) yields I3(aq) + 2CL(aq) + H2O(l)

-(4) (I3) (Starch) + 2S2O3 yields 3I + S4O6 + starch

5. combine equation 1-3 to show the overall reaction for the products of the starch-triiodide complex.

-(1) NaOCl(aq) + HCl(aq) yields HOCl(aq)+NaCl(aq)

-(2) HOCL (aq) + HCl(aq) + 3I(aq) yields I3(aq) + 2CL(aq) + H2O(l)

-(3) I3 + Starch yields (I3) (Starch)

6. What standard was used in this experiment?

7. Describe the naming of NaClO and HClO. What are the names of the following compounds? NaClO2 , NaClO3, NaClO4 , HClO2, HClO3, HClO4

8 Submit a one paged (typed double spaced) report that discusses the following topics:

a. the goals or objectives of the experiment

b.your results as they relate to the goals and objectives

c. the quality of your results.

I'm trying to find the amount of ethanol in an unkown solution by titration but I'm having trouble calculating it. Molarity of thiosulfate: 0.0806 M, amount of dichromate used: 15 mL

here is what my lab manual says:

The titration is based on the oxidation of ethanol with an oxidizing agent, such as potassium dichromate. Depending on the solution pH and the amount of potassium dichromate added, ethanol can be oxidized to ethanal (acetaldehyde, CH3CHO) via reaction 1, or to ethanoic acid (acetic acid, CH3COOH) via reaction 2:

3C2H5OH(aq) + Cr2O72-(aq) + 8H+ ? 3CH3CHO(aq) + 2Cr3+(aq) + 7H2O (1)

3C2H5OH(aq) + 2Cr2O72- (aq) + 16H+ ? 3CH3COOH(aq) + 4Cr3+ (aq) + 11H2O (2)

In order to ensure all ethanol has completely reacted via reaction 2, a known and excess amount of potassium dichromate (let’s call it potassium dichromate total) is added into a sample solution containing ethanol. The amount of unreacted potassium dichromate is then determined by reacting with potassium iodide solution via reaction 3 to form iodine:

Cr2O72- (aq) + 14H+ + 6I-(aq) ? 2Cr3+ (aq) + 7H2O(l) + 3I2 (aq) (3)

From the reaction 3, we know that 1 mole of dichromate ions can produce 3 moles of I2. Therefore, we just need to determine how much moles of I2 is produced in reaction 3, then, we can get the moles of unreacted potassium dichromate. Subtracting the moles of unreacted potassium dichromate from the moles of potassium dichromate total gives the moles of potassium dichromate that have reacted with ethanol. Then, from the stoichiometry of reaction 2, one should be able to know how much ethanol is in the test solution.

How to know the moles of I2 produced in reaction 3? The I2 is titrated with sodium thiosulfate (Na2S2O3) via the following reaction 4:

I2(aq) + 2S2O32-(aq) ? 2I-(aq) + S4O62-(aq) (4)

Experimental data: For the standardization of thiosulfate it took 31.7 mL of thiosulfate to reach the end point, for the unknown solution, it took 23.85 mL of thiosulfate to reach the endpoint. How do I use these numbers to find the amount of ethanol in the unknown solution?

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