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23 Nov 2019

How to find the slope in excel?

Basically, this is for a titration lab. Ihavethe volume and the PH. I need to find the average ofeachsuccessful point.
For example:
Graph:

Volume pH Slope
0.00 2.05 .......
0.95 2.06 ..........
1.90 2.07 .............
2.82 2.07 ................

So on and so on...
For example I need to find for each piece of data the change inpHover the change in volume. That will find me the slope. How canIget excel to do that?
Eventually I will find the equivalence point. I think I know howtodo that. (It's the one with the largest slope).

Here is the data in a image file:
http://i254.photobucket.com/albums/hh104/beethoven24680/IMG_0001.jpg
Here is the graph:
http://i254.photobucket.com/albums/hh104/beethoven24680/IMG_0004.jpg

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I am unable to solve these questions due to a time constraint. I received help on part 1 of the unknown acid. Need help with the rest! I really appreciate it!

Lab: ACID-BASE TITRATION

Objective: To use titration to determine in Part 1, the concentration (molarity) of an unknown acid solution and in Part 2, the purity of a sample of KHP acid. Background: Titration is a volumetric technique used to determine the concentrations of solutions, molar masses of solids, and purity of samples. A titration inolves the addition of a titrant (a solution of known concentration) to an analyte ( a solution of unknown concentration), or vice versa, using a piece of glassware called a burette. The titration is carried out until it reaches an equivalence point (the exact point at which the reaction between the two solutions is complete). A chemical indicator is often used to aid in the identification of the equivalence point. An indicator changes color upon reaching the equivalence point of endpoint. Since we will be carrying out an acid-base titration, the indicator must change color upon reaching the endpoint at a specific pH. An example of such an indicator is phenolphthalein, which changes from colorless to pink near the equivalence point when pH approaches 7. It should be noted that the indicator selected is dependent upon a given titration, so that the observed color change is close to the ideal equivalence point. Once the titration is completed, we can use the volumes measured for each solution, as well as the concentration of the titrant, to determine the concentration, molar mass, or purity of the unknown analyte. Procedure Note: During lab, record all measurements and data in a clearly labeled table. Part 1: 1. Obtain ~80mL of ~0.1M of base (sodium hydroxide, NaOH) into a labeled beaker. Make sure to report the actual concentration from the bottle. 2. Obtain ~25mL of unknown acid into a second labeled beaker. Record whether your acid is monoprotic, diprotic, or triprotic. 3. Using a funnel, or carefully pouring, fill the burette with sodium hydroxide NaOH. Make sure a labeled waste beaker is under the buretter to catch any drippings. Rinse your burette by filling it with ~5-10mL of NaOH. Turn the knob to let ~2 mL out the tip into the waste beaker. Make sure your waste beaker is under the burette to catch any drips. Next, turn the Burette upside down and pour the remaining NaOH into your waste beaker while twisting the burette to coat the inside with NaOH. 4. Fill your burette with sodium hydroxide. Turn the knob to fill the tip of the burette with NaOH. Record the initial volume to the correct number of significant figures. 5. Using a volumentric pipette, transfer 10.00 mL of your unknown acid into the Erlenmeyer flask. 6. Add 3 drops of pH indicator and magnetic stirrer to the Erlenmeyer. 7. Under the burette, place the Erlenmeyer on a hot plate and turn on the stir knob. Heat should be off. 8. Titrate the unknown acid until the solution turns pink and remains pink. 9. Record the final volume on the burette to the correct number of significant figures. 10. Repeat (4) to (7). Pre-plan the whole lab and who will do which task. MY RESULTS: PART 1 The actual concentration of NAOH is 0.5939, 80 mL Initial Final 24.9 mL 44.5mL 26.1 mL 45.57mL PART 2 Impure KHP (SAMPLE B ) Only Paper: 0.280 g Impure KHP Mass: 0.526 g Initial volume: 22.30 mL + water +26.10 mL Final Volume: 26.80 mL QUESTIONS: 1. Calculate the concentration (molarity) of your unknown acid. 2. Calculate how many grams in your impure KHP sample was indeed KHP. 3. Calculate the percent (by mass) KHP in the sample. Part 2: 1. What would happen to the final result( state what the final result is ) if the tip of the burette was not filled when reading the initial volume? 2. What would happen to the final answer if you used Ca(OH)2 instead of NaOH and DID NOT know it? 3. What would happen to the final result if the Erlenmeyer flask was contaminated with other types of acid? 4. Recalculate the concentration of your unknown acid if it was given as a diprotic acid. 5. Draw a molecular level picture (showing Na+, H+, OH-, H2O, etc...) of what is in your beaker before, at half point, at equivalent point, and at end point of the titration. Part 3: 1. What would have happened to the final result if the impurity in the sample was also acidic? 2. What would have happend to your final result if you used ~25mL of water to dissolve the solid acid instead of 20mL? Summary data: Create a clearly labeled table of all your final data results for each run, and athe average of multiple runs. Part 1: Unknown #, Vol base, M base, Vol acid, M acid. Part 2: Sample #, % KHP (purity)

I need help for my lab report please. It's only a-e Questions for study that I need help with, so any help or advice will be greatly appreciated! Underneath is more info on the lab if needed. Thank you!

Question for Study

1. A student performed this lab exercise, generating the following data:

Mass of H5IO6 used: 1.2320 g

Volume of thiosulfate used in blank titration: 47.93 mL

Volume of thiosulfate used in the unknown titration: 39.23 mL

a. What is the concentration of the sodium thiosulfate solution?

b. How many mmol of I3 â were present in the blank titration?

c. How many mmol of I3 â were present in the unknown titration?

d. How many mmol of glycol were present in the unknown titration?

e. What mass of ethylene glycol should be reported?

Introduction

The chemical analysis of organic compounds often presents major experimental difficulties. An accurate analysis depends upon the sample undergoing a single, well-defined reaction which quickly goes to completion. Often, organic compounds undergo several different reactions at the same time, and reaction rates are sometimes quite slow.

A functional-group analysis is one in which a particular grouping of atoms in a compound is made to react in a specific well-defined way with a particular reagent.1 In this experiment use is made of the reaction between an oxidizing reagent and an organic compound with the functional group COH-COH.

Analysis of Ethylene Glycol

Ethylene glycol reacts with periodate ion to form formaldehyde and iodate:

+ ð¼ð4 â â 2 ð»2ð¶ð +ð¼ð3 â + ð»2ð (8-1)

This oxidation-reduction reaction will proceed to completion with negligible side reactions under the appropriate set of conditions. The reaction is slow, but increases with increasing concentration of periodate. Here a known, fixed amount of periodate in excess of that needed to completely react with the glycol is added to the unknown. After the glycol has reacted, an excess of iodide is added to the solution. The iodide reacts with unreacted periodate according to:

ð¼ð4 â + 11 ð¼ â + 8 ð» + â 4 ð¼3 â +4 ð»2ð (8-2)

The iodide also reacts with the iodate produced in reaction 8-1 according to:

ð¼ð3 â + 8 ð¼ â + 6 ð» + â 3 ð¼3 â + 3 ð»2ð (8-3)

The triiodide produced in these reactions is then determined by titration with thiosulfate:

ð¼3 â +2 ð2ð3 2â â 3 ð¼ â + ð4ð6 2â (8-4)

To find the glycol content, a blank solution containing the same fixed amount of periodate but no glycol is treated similarly. The difference in the number of moles of ð¼3 â produced in the blank solution, and that produced in the sample solution, is equal to the number of moles of glycol in the sample solution.

Procedure

1. Prepare a solution from your unknown: a. Your unknown may have recently been refrigerated â make sure it is at room temperature before use. b. Transfer the vial contents quantitatively to a 250 mL volumetric flask. c. Dilute to volume with water and mix well.

2. Prepare a Periodic Acid standard solution (pronounced âpurr-eye-oh-dic acidâ): a. Weigh out 1.16-1.24 g of H5IO6 on an analytical balance. Periodic acid is very corrosive â to your skin and to metals. Do not spill any on the analytical balances. b. Quantitatively transfer the solid to a 100 mL volumetric flask, and dilute to volume with water.

3. Prepare a sodium thiosulfate solution: a. Weigh ~11.2 g of sodium thiosulfate pentahydrate. b. Transfer the solid to a 1L Pyrex bottle and dilute to 500 mL to produce an approximately 0.09 M solution. c. Add 0.10 g Na2CO3 and swirl to mix well.

4. Prepare a ~0.5 M solution of sulfuric acid: a. In a beaker (250 or 400 mL), combine 25 mL of 3 M sulfuric acid and 125 mL of water. Mix. Remember: âAcid Into Waterâ. What glassware is appropriate to measure these volumes?

5. Prepare samples for titration: a. Pipet 20 mL of your diluted unknown and 10 mL of the periodic acid solution into a 250 mL conical flask and swirl to mix. b. Wait a minimum of 45 minutes to allow complete reaction before titrating. Do the blank titrations while you wait! c. Prepare a total of 3 samples in this way.

6. Perform the sample titrations: a. Add ~1.5 g of KI to your conical flask and swirl to dissolve. b. Add 10 mL of your 0.5 M sulfuric acid (use a graduated cylinder). c. Titrate from a dark red initial colour to the first change to yellow. d. Add 2.0 mL of thiodene indicator solution. The solution will become a dark grey/violet colour. e. Finish the titration (fractional drops) to a sharp disappearance of the violet colour. 7. Perform the blank titrations: a. Pipet 10 mL of periodic acid solution into a 250 mL conical flask. b. Add 20 mL of water with a graduated cylinder. c. Add reagents and perform the titration as in Step 6 above. Calculations Report the total mass (in mg) of ethylene glycol in your unknown.

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