A 0.05% dilution of Lidocaine is being requested. If 0.5 ml of Lidocainc 1% is mixed with sterile water for injection, how many milliliters of water will be needed? How much 70% v/v isopropyl alcohol will be prepared by diluting 5 gal of concentrated (100% v/v) isopropyl alcohol? How much 70% v/v isopropyl alcohol will be prepared by diluting 4 gal of concentrated (100% v/v) isopropyl alcohol?
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You will need: seven kinds of plastic containers with different recycle codes, scissors, two cups or beakers, two stirring rods or wooden craft sticks, room temperature water, 70% isopropyl alcohol, graduated cylinder, acetone, 2 plastic pipets, hot plate with a 400 mL beaker of boiling water (student groups may share the boiling water), tongs, and forceps.
Cut a small, flat piece (1.5 cm ´ 1.5 cm) from each container (seven total) and start a data table to record the color and shape of each piece as well as the permanent marker letter label (AâG) your instructor previously marked on each container. If two containers are the same color, cut different shapes (triangle, rectangle, circle, etc.) to help with piece identification. Now you are ready to follow the flowchart. Record your observations in the data table as you go along.
Tap Water Test: Place all seven pieces of plastic in a beaker or cup of room temperature tap water. Stir vigorously with a stirring rod or wooden craft stick to dislodge any bubbles from the plastic pieces. Bubbles tend to adhere to plastics. How would this change the apparent density? Observe and record which pieces sink and which float.
70% Alcohol Test: Remove the pieces that float from the water. Add them to a beaker or cup containing about 20 mL of 70% isopropyl alcohol. Stir. Do the pieces sink or float in the 70% alcohol? How does the density of alcohol compare to water?
Using a plastic pipet, add a squirt of tap water to the beaker containing alcohol. Stir. Do any of the pieces begin to float? When adding water to 70% alcohol, how does the density of the solution change? Keep adding squirts of water and stir until one piece floats. According to the flowchart, what is the identity of this plastic? Remove the piece and record your results.
Add more squirts of water until a second piece floats. Remove the piece and record the identity of the second plastic. You can now identify the third piece since it is still sinking.
Boiling Water Test: Place the four pieces that sank in tap water in the beaker of boiling water for a minimum of 30 s. Using tongs, remove them one at a time and test their flexibility, noting their size and color. Record your results. Which plastics can you now identify using the flowchart?
Acetone Test: Place the final two plastic samples in a small amount of acetone for one minute. Record your results.
Check with your instructor to see whether you correctly identified the seven plastics. You are now ready for an unknown. If your unknown floats in the tap water test, you will need to use the known pieces for PP, HDPE, and LDPE along with your unknown to help you with the identification in the 70% alcohol test.
Table 1. Selected Physical Properties of Common Plastics | ||||
Number | Plastic Type and Composition | Density, g/mL | Glass Transition Temperature, °C | Melting Temperature, °C |
1 | PET or PETE: poly(ethylene terephthalate) | 1.38â1.39 | 60â85 | 250â265 |
2 | HDPE: high-density polyethylene | 0.95â0.97 | ~ â125 | ~138 |
3 | PVC or V-poly(vinyl chloride) | 1.16â1.35 | 81â98 | 200â300 |
4 | LDPE: low-density polyethylene | 0.92â0.94 | â128 to â30 | ~138 |
5 | PP: polypropylene (isotactic when all methyl groups are on the same side of the chain) | 0.90â0.91 | â8 | 174â177 |
6 | PS: polystyrene | 1.05â1.07 | 80â100 | 240 |
7 | PLA: polylactic acid (d and l conformations cause numbers to differ) | 1.25â1.26 | 50â80 | 173â178 |
Fill out the following table:
Letter Label | Sampleâs Color | Sampleâs Shape | Floats in Water? (Yes/No) | Sinkersâ | Sinkersâ | Floatersâ | Plastic Type |
A | |||||||
B | |||||||
C | |||||||
D | |||||||
E | |||||||
F | |||||||
G |
Using this information: I used 4.00 g potassium dichromate. The amount of Iron ll is 4.00 gram in 2nd flask. Used grey moose vodka 2.00 ml and filled flask with water. This was the 2% vodka solution. For the experiment I used 5.00ml of the vodka and added 35.00 ml of more water to make it 1/8 of 2% or 0.25% of the original. With this information and the answer's i have placed in the table please help with remainder of questions. Need to work to understand answers so I will get correct on upcoming test. Thanks.
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.
(a) volume of potassium dichromate solution added to the Erlenmeyer flask in mL | 5.00ml |
(b) coarse titration volume of iron (II) solution range in mL | 14.10 -14.15 ml |
(c) volume of iron (II) solution delivered from the burette in mL during the first fine titration | 14.13ml |
(d) volume of iron (II) solution delivered from the burette in mL during the second fine titration | 14.11ml |
(e) average volume of iron (II) solution used in the fine titrations | 14.12ml |
(f) the color of the analyte solution at the end point of the titration | purple |
(g) the color of the analyte solution after adding the indicator | dark green |
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.
(a) volume of potassium dichromate solution added to the Erlenmeyer flask in mL 5.00ml | |
(b) moles of dichromate ion added to the Erlenmeyer flask | |
(c) average volume of iron (II) solution delivered from the burette in mL 14.12ml | |
(d) moles of iron (II) ions delivered from the burette | |
(e) moles of excess dichromate ions that reacted with the iron (II) ions (remember that the ratio in which they react is 1 dichromate : 6 iron (II)) | |
(f) moles of dichromate that reacted with the ethanol in the vodka (Subtract excess dichromate ions that reacted with the iron (II) ions from the original moles of dichromate ion present.) | |
(g) moles of ethanol in the 5 mL diluted vodka sample according to the stoichiometric ratio of 2 dichromate ions to 3 ethanol molecules |
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 = Vsolute/Vsolution à 100
Find the percent alcohol (ethanol) by volume for the vodka used in the lab by following the steps outlined in the table below.
(a) given the molar mass of ethanol of 46.07 g/mol, calculate the mass of alcohol (ethanol) in the tested sample solution | |
(b) given the density of ethanol of 0.7893g/ml, find the volume in mL of ethanol present in the diluted vodka solution | |
(c) record the volume of vodka used in the experiment in mL | |
(d) find the percent alcohol by volume (% v/v) in the diluted vodka solution | |
(e) the diluted vodka solution was prepared by diluting 2.00 mL vodka to 100.00 mL. Calculate the dilution factor used (N:1) | |
(f) multiply the percent alcohol by volume in the diluted vodka solution by the dilution factor to obtain the % v/v alcohol in the original vodka solution |
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 Mn2+ ions 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.
% alcohol by volume | |
White rum | 37.0% |
Vermouth | 18.0% |
White whine | 12.0% |