Chem 151 Exam 3 Review
Yellow pigment 12 is unlikely to mix with water because it has larger regions of the molecule where dispersion forces will dominate and the size of the molecule will likely restrict the number of configurations resulting in an unmixed (UM) state with a higher number of configurations. Because the solubility is independent of temperature, both states will have the same PE. OR Yellow pigment 12 has polar regions and H-bonding regions (N-H bonds) so it could mix with water. As a result, the mixed (M) state will have a higher number of configurations. Because the solubility is independent of temperature, both states will have the same PE.
) One common pigment used for tattoos is yellow pigment 12, structure shown to the right. Construct a PEC-diagram representing the mixed (M) and unmixed (UM) states of this pigment in water. The solubility of this pigment is independent of temperature. Justify your reasoning.
(lowest) II < III < I (highest) II and III have similar numbers of electrons, but III is polar, so it will have a higher melting temperature. I has the most electrons, and it has a planar geometry that can maximize dispersion interactions. So I will have the highest melting temperature.
Acrylonitrile butadiene styrene (ABS) plastics are a common component of tattoo pigments. Shown below are the structures of three different forms of ABS plastics: styrene, 1,3 butadiene, and acrylonitrile. Order these compounds in order of increasing melting point.
ii, iii In addition to the amine (R-NH2) and the carboxyl (R-COO-R'), there is also a phenyl (the 6-membered ring with alternating double bonds).
Benzocaine is another type of topical numbing agent used by clients, structure shown to the right. What functional groups are present in this molecule? i. Hydroxyl ii. Amine iii. Carboxyl iv. Aldehyde
M has a higher PE and a lower # of configurations With mixed interactions of covalent molecules (nonmetals with nonmetals), the number of configurations drives mixing. Because Benzocaine is insoluble at all temperature (generally does NOT mix), the unmixed state (UM) will have a higher number of configurations. If an increase in temperature makes it slightly more soluble, the mixed state (M) must have a slightly higher PE.
Benzocaine is insoluble in water at all temperatures, but does show a slight increase in solubility at higher temperatures. Which PEC-diagram best represents the mixed (M) and unmixed (UM) state of benzocaine in water?
FeO With ionic compounds (metals with nonmetals), the stronger the force of attraction between the ions (based on their charge and size, here we are focusing on charge), the higher the melting temperature. Cr2O3 has Cr3+ and O2- ions, FeO has Fe2+ and O2- ions, and TiO2 has Ti4+ and O2- ions. The weakest attractions (lowest melting temperature) will come from the lesser charged ions: Fe2+ and O2-.
Cr2O3 is an ionic pigment used in green tattoo ink, and FeO is commonly used in black. Which of these pigments, including TiO2, would you predict to have the lowest melting point?
H-bonding interactions are drawn with 3 dots from the H (of an O-H, F-H, or N-H bond) to a F, N , or O atom on another molecule with a delta + on the H and a delta - on the other atom. Dipole-dipole must be oriented so that the positive end of one vector is oriented toward the negative end of the other vector. Dispersion is represented by a cloud of electrons, with random delta + on one molecule's cloud next to a delta - on the other molecule's cloud.
Given the structure of yellow pigment 12, draw one of each type of IMF interaction(s) that could take place between the pigment and the isopropyl alcohol (see table above for structure). You can draw as many isopropyl alcohol structures as needed to show all the possible interactions. Be sure to clearly label each interaction you draw.
2- Hydrogen bonding interactions would be expected to occur at the O—H bond between the two molecules. One of the molecules will have its H interact with the O (from the O—H bond) of the other molecule. The other molecule will also have its H interact with the O (from the O—H bond) of the other molecule. This will result in 2 H-bonding interactions.
How many hydrogen bonds are likely to form between two molecules of solvent red 1
III, IV There are ions (Zn2+) connecting two polymer chains (cross-linking).
Nitrile rubber polymer, shown below, is a polymer often used in tattoo gloves to replace latex due to an increasing number of people with latex allergies. It has similar properties, such as excellent elasticity, is soft, and strong. Also shown is a modified version of the nitrile glove polymer. The polymer has been functionalized, which allows for a specific type of interaction to occur between the chains, not possible in the unmodified polymer. What type of modification is shown and what type of interaction is it? i. Branching ii. Covalent iii. Ionic iv. Cross-linking
Lidocaine is not water soluble because of limited hydrogen bonding regions While Lidocaine has some H-bonding regions, it also has largely nonpolar regions. While it is not nonpolar overall and is not ionic, it must not be soluble because of the small number of H-bonding regions.
Numbing agents are used by some people when getting tattooed. Lidocaine is commonly used because it is fairly inexpensive and can be purchased over the counter. Lidocaine in the form shown to the right is not water soluble. Which statement is most accurate?
Both polymers have dispersion forces but the plastic cup has less branching than the plastic wrap. Branching in polymers reduces the surface area and the ability of the backbone chains to interact, which reduces the strength of the dispersion forces between the polymer chains. Because of that the limited branching in the plastic cup makes it harder and less flexible than the additional branching in the plastic wrap that makes it more flexible.
Other polymers commonly used in tattooing include the plastic cups used to hold water to rinse ink off the needles, and plastic wrap used to wrap the chair and table, as well as the skin after the tattoo is complete for healing and protection. Shown below are examples of each of these polymers. Justify why the polymeric unit corresponds to the specific type of plastic. Assume the chain length for both polymers is the same.
C—C < C—H < C—N < C—O
Solvent Red 1 (structure shown to the right) is soluble in fats and used to color various oils, waxes, and inks found in some tattoos. Rank the bonds in solvent red 1 from least to most polar
IV There is a regular repeating pattern of CH2-CHOH, so that means the polymer unit must reflect both of those.
Temporary tattoos have become increasingly more popular among children, as well as adults who may desire the look but aren't ready to make the commitment. These tattoos require a transfer film to be used which allows for separation of the image from the paper to the skin. Polyvinyl alcohol, PVA, is commonly used due to it being strong enough to adhere to the backing paper but flexible enough to be easily released during application. Given the picture of the polymer to the right, what is the polymer unit?
greater than 182 degrees While Solvent Red 1 has H-bonding interactions, Solvent Red 135 has a lot of Cl atoms. All of those Cl atoms increase the number of electrons and the polarizability of Solvent Red 135. This will make the dispersion forces for Solvent Red 135 stronger and it will have a higher melting point than Solvent Red 1.
The melting point of solvent red 1 is 182C. A different dye, solvent red 135, shown to the right, is used for non-tattooing purposes such as dying plastics. Predict the melting point of solvent red 135.
+4 O generally will have a +2 charge in an ionic compound (metal with a nonmetal). If 2 O atoms are necessary for 1 Ti in a neutral (uncharged) compound, then Ti must have a +4 charge.
TiO2 is a pigment commonly used in white tattoo ink. What is the charge of the Ti ion? +2 +1 0 +4
U3M3 material! Number of configurations is likely why potassium carbonate is more soluble than lithium carbonate because the potential energy of the dissolved and undissolved states for both ionic compounds are very similar. The two ionic compounds have the same charges, so size is the reason for the differences in their properties. Potassium is larger than lithium, so it has a lower charge density that has weaker ion-water interactions. The weaker ion-water interactions have less of a restricting effect on the water molecules making the dissolved state have a larger number of configurations. Lithium ion is much smaller and has a higher charge density that has a stronger ion-water interaction and a more pronounced organizing effect on water, reducing the number of configurations for the dissolved state making it less soluble.
Traditional tattoos from Hawaii and Polynesia use a mixture of soot and ash for ink. Ash has a high carbonate CO32- content through a chemical reaction between the ash and CO2 in the air. Two carbonate salt PEC-diagrams are shown to the right. Potassium carbonate is 100 times more soluble than lithium carbonate in water at the same temperature. (a) Using the PEC-diagrams and your knowledge of periodic trends, explain this difference in solubility. Be sure to specifically discuss potential energy and number of configurations in your argument.
U3M3 material! For Li2CO3, the dissolved state has a lower PE, so a lower temperature will increase the solubility. For K2CO3, the dissolved state has a higher PE, so a higher temperature will increase solubility.
Traditional tattoos from Hawaii and Polynesia use a mixture of soot and ash for ink. Ash has a high carbonate CO32- content through a chemical reaction between the ash and CO2 in the air. Two carbonate salt PEC-diagrams are shown to the right. Potassium carbonate is 100 times more soluble than lithium carbonate in water at the same temperature. (b) Discuss how changes in temperature affect the solubility of each? Clearly justify your reasoning.
Modifications could include: -adding an O—H or N—H to increase H-bonding interactions -adding a C=O to increase dipole-dipole interactions -adding an electron-rich atom (Cl, Br, I) to increase dispersion forces Increasing the interactions between the polymer chains make the polymer stronger.
Using the polymer unit for the plastic cup in part a) above, modify it in such a way that would create a stronger polymer. Draw the structure in the box, clearly showing your modification, and write a justification for your reasoning.
Hydrogen bonding, dipole-dipole, dispersion. The molecule has dispersion forces because it has electrons. There are dipole-dipole interactions because the molecule will have a net dipole moment. And there is an O—H bond, so there will be H-bonding interactions.
What types of intermolecular forces exist between solvent red 1 molecules?
3 The question is specifically looking for the hydroxyl group, which has a bent molecular geometry. Accounting for the geometry, the dipole will point through the O atom, bisecting the bent geometry.
Which of the images below represents the net molecular dipole moment of the hydroxyl group in solvent red 1? (NOTE: the position of the arrow on the molecule is not important; only its direction is relevant) See the powerpoint posted in D2L if image is hard to see.
III H-bonding interactions require that the partially positive H atom of a strongly polar O—H bond (in this case from the H2O) interacts with partially negative N atom (in this case from the Benzocaine). Note: the H atom from the N—H bond could also interact with the O from H2O.
Which picture below best represents a hydrogen bonding interaction between benzocaine and water? See Powerpoint in D2L if picture is unclear (I = a; II = b; III = c; IV = d)
no we predict that if the product of the charges is 4 or greater (in this case, |+4 x -2| = 6), then the ionic compound will be insoluble. More highly charged ions (+2 or -2 and greater) will have two reasons why they are less soluble: 1.the ions will have much stronger interactions with each other (PE) 2.the ions will have an organizing effect on water, which will drastically reduce the number of configurations possible for the dissolved state
Would you predict TiO2 to be soluble in water? not enough information no only at low pressures yes
All three molecules have dispersion forces, are polar so have dipole-dipole interactions and have O-H bonds so they can engage in H-bonding interactions. Because glycerin has the most electrons, and surface area the dispersion forces would be the strongest. Additionally, glycerin has the most H-bonding opportunities making it have the strongest interactions and the highest boiling point. Isopropyl alcohol has more electrons by fewer possibilities for H-bonding interactions than water, and therefore has the weakest interactions and lowest boiling point.
a) Tattoo ink is composed of two components: the carrier and the pigment. The carrier works to keep the pigment evenly mixed. Glycerin, water, and isopropyl alcohol are the most common carriers used in tattoo ink. Explain the data given in the table to the right. Please be sure to discuss each IMF in your answer.
