CHEM 181 Lecture Notes - Lecture 18: Caramel Color, Beta-Carotene, Carotenoid

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23 Feb 2018

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CHEM 181 Full Course Notes

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Play a very important role in terms of making our food more appetizing. The most widely used food colour in north america is caramel. As part of the process, a chemical is produced when we make caramel color. In california, according to proposition 65, any substance that is shown to be potentially carcinogenic in any type of situation must be labelled per say. Because caramel is the color that is used to color all the cola-like drinks. And we drink quite a bit of these drinks in north america. We get the caramel color from a plant. There is some concern that this might be a potential carcinogen. And to prevent this labelling, which would scare people off, pepsi cola and the makers of some drinks of that type have decided to use a different technology that does not use. This is another widely used natural food coloring.

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The above is what we did in the lab

Down is the question

Today you are going to take a closer look at the light emitted from a wide variety of different types of matter. Before experimenting with these different light sources, make a large table in your lab notebook with columns listing the major regions of the visible spectrum (ROYGBIV). As you collect data by looking at different light sources, you will keep adding rows of observations into this table. The general layout should look something like this: Once you have your lab notebook ready, collect some observations about these different systems by performing the following experiment: At your bench, you should find a small handheld spectroscope through which you can split the visible spectrum apart and carefully observe each color region in the spectrum. For the first light source, set up and light the votive candle inside the metal pan (the metal pan is just to keep wax from dripping all over the benchtop). Then, look through the spectroscope at the burning candle. In your lab groups, predict what you think the emission spectrum will look like from a light source (flame) that is made by burning the ionic compound SrCI_2. With your prediction, provide a molecular-level justification that supports why you think the emission will look the way you predicted. Write the predictions and explanations down in your lab notebook (with a heading/label for your TA - as you should be doing for every activity). Fill a 400mL beaker about % of the way full with tap water and keep it near your area to use as a waste beaker for used matches and burning applicators. You should have a second beaker containing cotton-tipped applicators soaking in deionized (Dl) water (be sure the applicators are NOT placed in tap water). Into the 24-well microplate, add enough of the solid test samples that have been provided in the lab so that the solid just barely covers the bottom of each well. Be sure to record the identity of each solid you test. Note - be very careful not to cross-contaminate between wells as this will significantly skew results (even a single small crystal can cause a large contamination issue). Remove the candle and place the Bunsen burner in the center of the metal baking pan (the pan will help catch any burning solids that drip or spatter from the flame tests you will be performing). Your TA will demonstrate how to light and adjust the burner being used in our labs here at CSU (avoid fireballs in your face or your lab partner- listen to the TA's directions). To observe the flame colors, you will be placing the salts on the end of water-soaked wooden applicators. When placing the applicators into the burner flame, you only have a limited amount of time before the color will disappear and the applicator begins burning so you should be prepared to make observations as soon as you place the applicator into the burner flame. Also, while performing these steps, one member of your lab group should be observing the flame with the spectroscope while another group member handles the actual burning and observes just with their eye. You should record as much information as you can about the burning behavior including color, intensity, and any other details you notice. In your groups, predict what you think the spectrum would look like for a light-emitting diode (LED) light source. LEDs are made up of solid-state materials. What do you expect to see in the spectroscope while looking at a lit LED? Write this prediction down in your lab notebook and be sure to include a heading so your TA can find this prediction while reviewing your lab notebook pages later. Test your prediction by performing the following experiment: Setup the 9V battery and wire leads as shown below - the foam card that the LEDs are mounted may be clamped into a ring stand to hold it upright for easier viewing. Connect the alligator clips coming from the battery one LED at a time. The red alligator clip should be connected to the longer (+) lead of the LED bulb. The black alligator clip is connected to the shorter (-) lead of the LED bulb. If you reverse the wire leads, the LED will not light. Once connected to the battery, note the macroscopic color of the LED bulb that you can see with your eye, then look through the spectroscope at the lit LED bulb. As you examine the LED with the spectroscope, carefully note and rate the relative appearance/intensity of each of the color regions in the visible spectrum (ROYGBIV). After you have collected all your observations, your TA will demonstrate how to use a different type of spectroscope attached to the laptop computers (SpectroVis Plus). After your TA has demonstrated how to use the instrument, collect spectra for all the LED bulbs by following these Identify and write three (3) new and well-thought-out scientific questions related to the light emitted from a firework. For credit, these new questions MUST follow these guidelines: Questions must be molecular-level and focused on the behavior of the chemical components within fireworks Questions should be directly related to the light emission concepts covered in this lab

Observations In columns 3 and 4, record the color and intensity seen. In columns 5 and 6, determine if the substance is an acid or a base, and if the substance is ionic. For the last column, determine which chemical species is acting as an acid or base.

Data Table 1: Acids and Bases Acting in Water
Well	Substance	1drop BTB	Plus 1 drop of substance	Acid or base (Q1)	Ionic? Y/N (Q2)	Species acting as acid or base (Q3)
1	NaHCO3
2	CH3COOH
3	HCL
4	Na2CO3
5	H2SO4
6	CH3COONa
7	NaOH
8	HNO3
9	NaHSO4
10	NH3
11	H3PO4
12	NaH2PO4
13	Na2HPO4
14	Na3PO4
15	NaHSO3

Data Table 2: Following Acid/Base neutralization reactions
Well #	1 Drop of Each	Observation	+2 Drops Acid	Observation	+2 Drops Base	Observation
1	BPB + NaOH		HCl		NaOH
2	BPB + NaOH		H2SO4		NaOH
3	BPB + NaOH		CH3COOH		NaOH
4	BPB + NaOH		H3PO4		NaOH
5	BPB + Ca(OH)2		HCl		Ca(OH)2
6	BPB + Ca(OH)2		H2SO4		Ca(OH)2
7	BPB + Ca(OH)2		CH3COOH		Ca(OH)2
8	BPB + Ca(OH)2		H3PO4		Ca(OH)2
9	BPB + NH3		HCl		NH3
10	BPB + NH3		H2SO4		NH3
11	BPB + NH3		CH3COOH		NH3
12	BPB + NH3		H3PO4		NH3

Please note here if any of the other starting materials is other than a clear, colorless solution.

Data Table 3: Investigating Odor as a Means of Indicating Neutralization.
Substance(s)	Odor
2 Drops of HCl in Well #1
1 Drop of Ammonia on Swab
Swab with Ammonia & HCl

Data Table 4: Investigating Evaporation as a Means of Indicating a Neutralization Reaction.
Reaction Mixture	Observation (When Wet)	Observation (When Dry)
HCl + NaOH
CH3COOH + NH3
HNO3 + NaOH

PART 5: Mini-Experiments

1. Use BTB to classify four household products as acidic or basic. Possible substances to test include home cleaning products, glass cleaner, liquid detergent, bleach, soft drinks, liquid from food items, etc. Remember to:

a. Hypothesis (What you think will happen and why) or purpose:

b. Method used to test your hypothesis:

c. Data and Observations Put your data and observations in the space below. You can include pictures that you âdraw.â

d. Conclusions

2. Find one common, highly colored substance that can be used as an acid-base indicator.

Possible substances include fruit/vegetable juice or products, inks, food coloring, flower

petals, etc. If using fresh fruit, veggies, or flowers, crush the substance with a little water or

rubbing alcohol to extract the colored pigments. If red cabbage is available, it makes a superb

acid-base indicator. Then use a few drops of the colored extract as the indicator. Test four

more household products using the freshly made acid-base indicator. Remember to:

a. State a hypothesis or purpose.

b. State the testing method.

c. Use the prepared indicator to test four substances known to be acids or bases from either the LabPaq or home materials and record results.

d. State conclusions in terms of the hypothesis or purpose.

Questions

A. Review the substances used in Part 1. Determine whether each substance contains an acid or a base based on the BTB results. Place answers to this question in column 6 of Data Table 1.

B. Review the responses to Question 3. The anion that is produced in the dissociation of the compound goes on to react with the water. Identify the anion product in each reaction. Place the formulas for these species into column 7 of Data Table 1. If the substance is not ionic and thus does not dissociate, then list the substance in column 7, just as it appears in column 1.

C. For each ionic species in Data Table 1, write the equation showing the dissociation of the compound in water. Hint: thereâs one for each line provided below.

a. NaHCO3 Ã Na

+ HCO3

Review the responses to Question 3. The anion that is produced in the dissociation of the compound goes on to react with the water. Identify the anion product in each reaction. Place the formulas for these species into column 7 of Data Table 1. If the substance is not ionic and thus does not dissociate, then list the substance in column 7, just as it appears in column 1.

D. Write the reaction of each acid or base the substance listed in column 7 with water.

Acids: Bases:

a) HCO - + H-OH Ã H CO

+ OH-

3 2 3

1. What is produced in each and every reaction of an acid with water?

2. What is produced in each and every reaction of a base with water?

E. Review the results in Data Table 2. For each reaction mixture, write the reaction equation describing the acid/base neutralization reaction:

2) 2NaOH + H2SO4 Ã 2H2O + Na2SO4

F. Define the term âneutralizationâ and provide an example of a neutralization equation. List the three ways used in this lab to detected neutralization.

G. Define the term âsalt,â and provide an example.

H. Review Data Table 3. What happened when the two chemicals were mixed? What indicates that conclusion? What reaction took place?

I. Review Data Table 4. What happened when the solution mixtures on the glass slide were heated? Describe the process that took place.

J. In Part 4, for HCl + NaOH, what is left on the slide after heating? Provide the formula. What is the common name of this substance?

CHEM 181 Lecture Notes - Lecture 18: Caramel Color, Beta-Carotene, Carotenoid

CHEM 181 Full Course Notes

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