Hot Ice: Synthesis and Characterization of Sodium Acetate Trihydrate
Note: This video assumes 80% acetic acid AKA "vinegar concentrate", not the usual 5-6% strength. It is much more hazardous and gives off unpleasant fumes. I do not currently have any 80% vinegar in stock. I currently have a stock of 30% acetic acid solution, so plan for that.
Part I: Synthesis of Sodium Acetate Trihydrate (NaCH3COO.3H2O)
Reaction: NaHCO3 + CH3COOH + 2 H2O → NaCH3COO.3H2O + CO2
Write a procedure for synthesis of sodium acetate trihydrate from baking soda (NaHCO3) and 30% acetic acid solution (i.e. 300 grams of acetic acid per liter) based on the references given here and any other sources you have found. Be sure to cite your sources!
If you are leaving a solution of sodium acetate out to evaporate and crystallize, please cover it with cheesecloth. Otherwise you may find it full of dead fruit flies in the morning. Whoever said 'you catch more flies with honey than with vinegar' never actually did the experiment: fruit flies love vinegar.
Despite the video, I do not allow you to handle chemicals with your bare hands in the laboratory. That can just end badly in so many ways.
Part II: Supercooling and Crystallization of Sodium Acetate Trihydrate (NaCH3COO.3H2O)
You will require pure, crystalline sodium acetate trihydrate for this. Take some of it and heat it until it melts - this can be done by immersing a test tube into hot water. The molten sodium acetate trihydrate can be set aside to cool. If the glassware and the sodium acetate trihydrate itself are both perfectly clean, the melt will actually stay liquid at room temperature. However, it is actually below its freezing point! We call this a supercooled liquid.
If you pour your molten sodium acetate trihydrate into a beaker containing a single crystal of solid sodium acetate trihydrate to act as a 'seed crystal', it should all crystallize. Feel the beaker: does it get hot? Does it get cold? Why? Is freezing exothermic or endothermic?
How fast does this crystallization happen? You could spread out some plastic wrap onto a benchtop and carefully pour a trail of supercooled sodium acetate trihydrate liquid. Then you could touch a seed crystal of sodium acetate to one end of the trail, and time how long it takes for the crystallization to reach the other end.
Part III: Heat Storage of Sodium Acetate Trihydrate (NaCH3COO.3H2O)
Weigh out a known amount of sodium acetate trihydrate. If your synthesized supplies are insufficient, I may be able to provide you with some more. Melt it and allow it to cool to a supercooled liquid. Be sure to use a very clean container and avoid any dust or debris, which may cause your supercooled liquid to crystallize prematurely.
Use a thermometer to measure the temperature of the liquid before and after it crystallizes. You may add a small 'seed crystal' of solid to start the crystallization if necessary.
Calculate the heat energy given off: the change in temperature, ΔT, multiplied by the specific heat capacity (C) will give you the energy given off by crystallization in units of J/mol. You can multiply this value by the molar mass (in g/mol) to obtain the energy in J/gram.
Compare this with values from the "Chalk Dust Magazine" article and the Wikipedia entry. Is it comparable?
Compare this with the energy density of lithium batteries. Is this a good means of energy storage?
Bananas and Wintergreen: Ester Synthesis Project
Esters are a class of organic compound which often have distinct odors (and flavors, but we don't eat anything we make!) You may have already synthesized an ester, ethyl salicylate, from aspirin, but if not, it's okay. Esters are generally formed from a carboxylic acid (R-COOH) and an alcohol (R'-OH). This reaction is a double displacement where the -OH of the acid and the -H of the alcohol become water, H2O. Organic chemists refer to this type of reaction as a 'condensation'. This reaction will not happen without a catalyst. Either acid or base catalyst may be used, but we generally use sulfuric acid (H2SO4). Sulfuric acid is a good catalyst for esterifications because it tends to soak up the water product and drive the reaction forward.
Safety note: Concentrated sulfuric acid is extremely hazardous, a single drop can produce a burn with a lifelong scar and can permanently blind an eye instantly. You will never handle it: I will either mix it with your reaction myself, or provide you a premade mixture of sulfuric acid. The mixture is still hazardous, but not as much as concentrated sulfuric acid. Gloves, goggles, and an apron are a must!
Part I: Synthesis of isopentyl acetate (Commercially sold as "Banana Oil")
Reaction: C5H12O + C2H4O2 → C7H14O2 + H2O
I am attaching a reference for the preparation of isopentyl acetate (AKA isoamyl acetate). We currently do have glassware for a 'reflux' setup. We do not have an 'electric flask heater' but we do have a 'sand bath' setup which we have used successfully in the past. We do have separatory funnels as well. We may skip the 'distillation' step here.
Once you've got a workable procedure, we can try it!
Part II: Synthesis of methyl salicylate ('oil of wintergreen')
Reaction: You can figure it out!
Instead of acetic acid (C2H4O2), you'll be using salicylic acid. We may have already made salicylic acid from aspirin. Instead of pentanol we will use methanol. Please adapt the procedure to prepare methyl salicylate.
In previous years, we tended to obtain poor yields of methyl salicylate due to the difficulty of separating it from the water layer during workup. Due to this, we should add a step: instead of just using the separatory funnel to separate the methyl salicylate from the water layer, we may add the solvent ethyl acetate. This solvent also floats on water, and will hold nearly all of the methyl salicylate. To separate the mixture of 2 liquids, we will need to plan and do a distillation. We do have glassware for this. Which liquid should distill off first, and at what temperature? Please look this up and plan accordingly. Cite your references!
We may have already demonstrated that ethyl salicylate, when mixed with sugar and ground in a glass mortar in the darkroom, gives off light. Try the same experiment with methyl salicylate. Does it work? How well?
Please be aware that methyl salicylate is toxic. A single milliLiter is roughly equivalent to 4 aspirin pills. It used to be sold as an 'essential oil'. A student athlete in New York died a few years ago from overusing over-the-counter muscle ache creams, and our pure methyl salicylate is much more potent than the dilute medical preparations. Treat the pure 'oil of wintergreen' with respect as you would any other chemical!
Synthesis of Isopentyl Acetate (Department of Chemistry, Chulalongkorn University, www.chemistry.sc.chula.ac.th/bsac/Org%20Chem%20Lab_2012/Exp.8.pdf)
Manganese Violet Pigment Project - A Quest for New Colors
Manganese violet is a pigment we use every year for the 'Make Your Own Paint' activity. Last year, we found an optimized procedure giving high-quality pigment, thanks to the Gold Alpacas and the Magnesium Monkeys. This year, we will repeat this, and attempt to prepare new pigments by 'doping' various s-block metal ions into the product.
Part I: Preparation of Monoammonium Phosphate
Reaction: H3PO4 + NH3 → NH4H2PO4 (monoammonium phosphate, the desired product)
We have household ammonia, approximately 3 Molar NH3 in water. We also have more concentrated ammonia, known as 'ammonium hydroxide', having a concentration of about 14.5 M: due to strong irritant fumes, this must be handled in the fume hood in room B119. We also have 85% phosphoric acid, H3PO4. Note that this is a concentrated acid and a hazard.
The reaction itself is simple: figure out how much monoammonium phosphate you want (a 50 gram scale should be good), calculate how much ammonia solution you need, and then slowly mix in phosphoric acid with stirring until the reaction mixture is acidic by pH paper (red spot). Once you've done the reaction, you should have a solution of monoammonium phosphate. You will need to crystallize it and collect the solid monoammonium phosphate for the next step.
Alternatively, you may be provided with monoammonium phosphate and start at the next step.
Part II: Preparation of Manganese Violet
Reaction: NH4H2PO4 + MnO2 + H3PO4 → NH4MnP2O7 + ?????? (this reaction is not completely understood)
As described in the reference 'Preparation of Manganese Violet' below, monoammonium phosphate (NH4H2PO4 ), manganese dioxide (MnO2 ), and phosphoric acid (H3PO4 ) are heated in a ceramic dish together. Once the reaction is complete, the mixture is boiled in water to remove soluble impurities, collected on a filter, and dried.
Here's the tricky part: the 'preparation of manganese violet' paper has amounts which are wrong. Last year, the Gold Alpacas and Magnesium Monkeys found the correct amounts to obtain good pigment: we ended up using 2.5 grams of MnO2 with 10.6 grams (0.092 moles) of NH4H2PO4 and 12.5 grams of 85% H3PO4. Hopefully you can reproduce their results.
Part III: 'Doping' Mn Violet with S-Block Metals
M2CO3 + 2 H3PO4 → 2 MH2PO4 + CO2 + H2O ['M' is a Group I metal]
MCO3 + H3PO4 → M(H2PO4)2 + CO2 + H2O ['M' is a Group II metal]
(x)MH2PO4 + (1-x) NH4H2PO4 + MnO2 + H3PO4 → M(x)(NH4)(1-x)MnP2O7
In this reaction scheme, (x) is a number between 0 and 1. We are attempting to prepare what is called a 'nonstoichiometric' compound. While most compounds do obey Dalton's laws, these compounds do not, because they feature ions of similar size which can replace each other. The ammonium ion, NH4+, is similar in size and chemistry to s-block metal ions. We are hoping to replace some of the ammonium ions with s-block metal ions in order to change the crystal structure of the pigment and thereby obtain new and interesting colors from the Mn(III) ion. Nonstoichiometric compounds are important in electronics: most semiconductors are nonstoichiometric compounds. Many alloys are also nonstoichiometric compounds.
Some of you may have already made 'Rinman's Green' pigment, Co0.1Zn0.9O. If not, I may have a sample I can show you. While cobalt (II) oxide is a black color, and zinc oxide is bright white, the non-stoichiometric compound we produced is not gray: it is in fact green. We are hoping to find similar effects in the Manganese Violet pigment system.
Raspberry Ketone Project
Part I: "Aldol Condensation" of 4-hydroxybenzaldehyde with acetoneReaction: C7H6O2 + C3H6O → C10H10O2 + H2O.
A "condensation" is what organic chemists call a double displacement where one product is water.Last year, we successfully obtained good results in this reaction using the procedure in reference . It is important to mix throughly after adding each reactant - do not simply mix at the end! The reaction will not work that way. We did scale up the reaction by a factor of 4, and did the reaction in an Erlenmeyer flask rather than a screw-capped test tube. We may possibly be able to verify the purity of the product using facilities at UMass-D this year.Safety Note: This reaction requires the use of NaOH or KOH base. These are strong bases and can cause severe burns!Part II: Hydrogenation of 4-hydroxybenzalideneacetone to raspberry ketone (AKA "Frambinone" or "Rheosmine")
Note: I would write it NH4HCO2, with the ammonium cation first, 'ammonium formate'. Why is it useful? It's basically solid hydrogen storage: it gives off NH3, CO2, and H2. The H2 adds across the double bond under the influence of the Pd catalyst to give a single bond.Reaction: C10H10O2 + NH4HCO2 → C10H12O2 + NH3 + CO2We followed the 'Step 2' procedure in reference  last year. Where the procedure uses dichloromethane as a solvent, we replaced it with ethyl acetate - it is much less toxic, and works well. Note that while dichloromethane sinks in water and will form a layer below it, ethyl acetate floats up to the top. If we can obtain successful reaction, we may wish to repeat the reaction at a larger scale - perhaps a 4x scaleup as in step 1. Again I am hoping that we can verify the purity of the product using UMass-D facilities this year. If necessary we might purify by recrystallization, but that would require scaling up the reaction.Safety Note: This reaction is performed in methanol as a solvent. Methanol is toxic and flammable. Furthermore, the palladium-carbon catalyst is quite capable of igniting methanol vapors. For this reason the catalyst must be added to the reaction before the methanol. I will dispense the methanol into your reaction for you, and we will conduct this reaction on a small scale so that if it does ignite, it will not endanger anyone. If a small reaction catches fire, it is best to cover it to exclude oxygen.References:
Iron Oxalate ProjectPart I: Preparation of FeC2O4.2H2O (Iron (II) Oxalate Dihydrate) and "Pyrophoric Iron"Reaction 1: Fe+2 + H2C2O4 → FeC2O4 + 2 H+Reaction 2: FeC2O4 → Fe + 2 CO2Reaction 2 is conducted by heating a small amount (<0.5 g ) of FeC2O4 in a test tube. The product is iron, but a very special form of iron : it has a very high surface area due to being composed of fused nanoparticles, and therefore it is so chemically reactive that it will ignite upon contact with air.Part II: Preparation of Na3Fe(C2O4)3 and K3Fe(C2O4)3 (Sodium and Potassium Ferrioxalate)Reaction: 3 K2C2O4 + 2 FeC2O4 + H2C2O4 + H2O2 → 2 K3Fe(C2O4)3 + 2 H2OReaction: 3 Na2C2O4 + 2 FeC2O4 + H2C2O4 + H2O2 → 2 Na3Fe(C2O4)3 + 2 H2ONote: Na2C2O4 and K2C2O4 will probably have to be prepared by reaction of H2C2O4 with NaOH or KOH respectively.Both Na3Fe(C2O4)3 and K3Fe(C2O4)3 are light sensitive: upon exposure to light, they decompose. Research this reaction and devise a demonstration of it.Last year we successfully used the procedure in reference  to prepare both these salts - different groups chose each target compound. Note that in this procedure, we've basically already done steps 1 and 2. You will have to change the scale of the following reaction to use the particular amount of FeC2O4. We also used 12% H2O2 instead of the approximately 6% solution mentioned in the procedure. Also, when we did the final crystallization, we did not add ethanol immediately: we left the solution overnight in the refrigerator and found that some impurities crystallized out, which we removed by filtration. The purified solution was then crystallized in the fridge after ethanol addition.Part III: Growth of 'mixed salt' crystals of K5Na(Fe(C2O4)3)2Reaction: 5 K3(Fe(C2O4)3).3H2O + Na3(Fe(C2O4)3).3H2O → 3 K5Na(Fe(C2O4)3)2Grow crystals from a saturated solution of both potassium and sodium ferrioxalate salts. Note that these salts decompose in the presence of light, and the crystallization may take days or weeks, so a safe location for the experiment must be found.References:
Cinnamon to Strawberry and SpiceCinnamaldehyde, as the name suggests, is the main component of cinnamon essential oil, and it is an aldehyde. As it is a purified essential oil component, it should be handled with the respect due any other chemical: a bottle of cinnamon flavoring from the grocery story might only have 1% of cinnamaldehyde. In this project, we can try to turn cinnamon into strawberry-scented ester. If time permits, we can also attempt to prepare a 'floral spice' flavoring compound. Note that, as our lab is not food grade and neither are our ingredients, we never taste anything we make. We may 'waft' the odor, though.Part I: Cannizzaro Reaction of CinnamaldehydeThis is an old reaction, recently of new interest as a type of 'Green Chemistry'. Cinnamaldehyde is measured out into a mortar, along with solid sodium hydroxide, and the mixture is ground for about 30 minutes. I used 5 mL of cinnamaldehyde with 1.06 g of NaOH. For safety reasons, we need to cover the mortar with saran wrap or something similar to avoid splashing: cinnamaldehyde is an irritant, and sodium hydroxide is very corrosive and causes severe burns or even blindness. The crude reaction mixture may be left overnight to complete reaction. At this point, it will be a gummy solid.The mixture is then transferred out of the mortar into a beaker using a spatula. The mass is dissolved by addition of 30 mL of ethyl acetate and 20 mL of water. You may use more if necessary, but there will likely be some insoluble solid left over. Remove by filtration if necessary, and transfer into a separatory funnel. The used mortar should be left to soak in acetone overnight for cleaning.The 2 layers should separate in the separatory funnel. The bottom layer is the water layer: it now contains the salt sodium cinnamate. Separate off this layer and add about 50 mL of 2M HCl (hydrochloric acid). The cinnamic acid product should precipitate and can be collected on a filter and left to dry.The top layer is the ethyl acetate layer, which contains cinnamyl alcohol and other impurities in solution. Wash this layer with 30 mL of water to remove leftover NaOH, followed by 2 portions of 50 mL of NaHSO3 solution (sodium bisulfite) to remove leftover cinnamaldehyde, and if the layer still looks 'cloudy' wash with 50 mL of brine (NaCl). This solution can be stored if necessary. The next step is to distill off the ethyl acetate solid, leaving behind the cinnamyl alcohol product.
Our products will hopefully be tested for purity using facilities at UMass-D, if available.Part II: Esterification of Cinnamic Acid to Methyl Cinnamate (Strawberry!)This is an esterification reaction where a carboxylic acid reacts with an alcohol yielding an ester and water (not shown) - see the above project for 'Bananas and Wintergreen'. For details of this particular reaction, see reference  below. We will not be using ether as an extraction solvent: I have ethyl acetate available instead.Part III: Esterification of Cinnamyl Alcohol to Cinnamyl Acetate (Floral Spice!)As I have had difficulties obtaining reasonably pure cinnamyl alcohol, we should hopefully only do this after we have verified the purity of our cinnamyl alcohol. We will have to develop our own esterification procedure for this reaction, as I could not find one - again see above in 'Bananas and Wintergreen'.References:
Electrotyping: Using Electricity to Copy a 3D Object in Solid CopperElectrotyping is a process for copying a 3D object into copper. How is it done? A mold is made from the object, using wax or a similar substance. The mold is coated with a conductive layer : powdered graphite, powdered copper metal, or perhaps conductive ink.Copper is then deposited onto the mold by electrochemistry. A solution containing Cu+2 ions is used as the electrolyte. The mold is immersed into the solution and is connected to the negative terminal of a power supply. A copper "anode" is also immersed into the solution, and is connected to the positive terminal of a power supply. When the current is turned on, copper loses electrons at the anode and goes into solution as Cu+2 ions. These ions are then attracted to the negative electrode (cathode) and travel through the solution until they reach it. Once there, they pick up electrons and become copper metal again. This fills the mold with copper metal.This technique was once routinely used to duplicate printing plates, before modern technologies for printing made it obsolete. It is still used by museums to duplicate works of art, ancient coins, and such items.
Part I: Make me a copper quarter!I have literally always wanted a quarter of solid copper. Or perhaps, a Kennedy half-dollar, or an old-time silver dollar, any big coin which would look wrong if it was made of copper. I would be happy to provide the coin, or you can duplicate a coin or similar object of your own. Making a 2-sided mold might be beyond our capabilities but we can just go for a single-sided coin to start with. We can consider trying for 2 sides later.
Plan a procedure for doing this, taking into account available equipment here at school. I can answer any questions you need about what we have or could get. Reference  below contains information on how to make the electrolyte solution and how to set up the experiment using a 3-volt battery and a rheostat. We will be using a modern solid-state power supply which provides variable DC voltage, so plan accordingly.Duplicate coins made by professionals are shown below.Part II: Cross-disciplinary Collaboration (3D Printing in Copper)
We have multiple 3D printer installations here at Diman. They can only 'print' in certain types of plastic. Investigate current 3D printing projects and find a reason (or at least, an excuse) to duplicate a 3D-printed item in copper.Alternatively, look into using electrotyping to produce useful items for some shop: electronics, perhaps? Plumbing?References: "Electro-Plating Nickel and Copper" and "To copy a scout badge or medal by electrolysis", United Nations Educational Scientific and Cultural Organization (1962), 700 Science Experiments for Everyone Garden City, New York: Doubleday & Company Inc. (p 189-190)Luminol: The 'Volcano' and the 'Oscillating Glow Stick'"Luminol", known to organic chemists as 3-aminophtalic hydrazide, can be oxidized by hydrogen peroxide in the presence of a catalyst to produce a molecule in an 'excited' state. The excited electrons will return to their ground state with emission of photons. That's why it glows!Part I: The Luminol VolcanoIn this experiment, luminol reacts with hydrogen peroxide using sodium carbonate as a base and copper (II) sulfate as a catalyst. Light should be emitted, as well as some offgassing of oxygen bubbles. Please adapt the procedure in the above video and described on the MEL website here to our own laboratory, as we do not actually have the MEL kit: thankfully, the bottles seem to be well labeled and you should be able to construct a procedure from there.
Ideally you'll be able to capture pictures and/or video for your final presentation: you may have to work in the darkroom for some of this.Part II: The Oscillating Luminol ReactionAs reference  below describes, a solution containing H2O2, KSCN, CuSO4, NaOH together will undergo oscillations in concentrations of various substances. This is visible as a repeated change in reaction color between yellow and colorless. This is not a very spectacular reaction, but can be made visually exciting by addition of luminol. The yellow species in solution is thought to be a complex ion of formula Cu(O2H)(OH)2-2. This complex will catalyze the reaction of luminol with hydrogen peroxide, yielding repeated pulses of light.Please construct a procedure to reproduce the oscillating luminol experiment of 'NurdRage' as shown in the following video:
Again, pictures and/or video are highly desirable!
Part III: Modifications of the Oscillating Luminol ReactionDesign some experiments to help us learn more about this (very complicated!) reaction.NurdRage has his reaction constantly mixed by a magnetic stirbar. What happens if you conduct this reaction in a shallow dish with no stirring at all? Do you see waves or swirls of luminescence? What if we conducted it in an unmixed graduated cylinder or length of plastic tubing?What happens if you use less or more copper (II) sulfate than in the video above? Can we obtain faster or slower pulses? What about changing the amount of potassium thiocyanate (KSCN)? Can we 'time' this reaction to our specifications?References:
"Singing Crystals": Rochelle Salt and Piezoelectricity
Crystals of Rochelle Salt, KNaC4H4O6·4H2O, used to be commonly used in microphone and small loudspeakers due to their property of 'piezoelectricity'. Piezoelectricity means that voltage applied to a crystal will cause small size changes which can produce sound, or alternatively, vibrations applied to a crystal will produce electrical signals. This is applicable to the construction of both loudspeakers and microphones. Today other piezoelectric materials are more common, but rochelle salt is easier to make.Part I: Synthesis of Rochelle SaltReaction: KHC4H4O6 + NaHCO3 + 3 H2O → KNaC4H4O6·4H2O + CO2As described in Reference  below, Rochelle salt can be made from common grocery store items. The ingredients here are sodium bicarbonate (NaHCO3) and cream of tartar (potassium hydrogen tartrate, KHC4H4O6).Supermarket "cream of tartar" may not be pure (potassium hydrogen tartrate, KHC4H4O6. To purify it, recrystallize it from boiling water as described in Reference 1. Be aware that boiling water can cause very severe burns! This would be a great step for your first project lab day. If I can obtain a purer grade of potassium hydrogen tartate, skip this step. Don't worry about the sodium bicarbonate (baking soda), as it is generally sold as a highly pure substance.Once you have made or obtained purified potassium hydrogen tartrate, plan the synthesis as described in Reference . Be sure to work out a full reaction table with grams and moles and such.Part II: Growing crystals of Rochelle SaltOnce you have obtained solid crystals of Rochelle Salt, you may be disappointed that they aren't larger. We will want large crystals to make 'singing crystals', with as few imperfections as possible. As described in reference , you will need to use an existing crystal of your Rochelle salt as a 'seed crystal' - you will hang it using fishing lineinto a saturated solution of Rochelle salt and allow slow evaporation. It may take days or weeks to grow a proper crystal of Rochelle salt: we need to find an area for this experiment where it will not be excessively disturbed. Reference  suggested a warm, temperature controlled enclosure - we may consider finding or making one.Part III: Make a Loudspeaker or a MicrophoneDetails of contruction may be found in Reference  and you are free to do your own research as well. The basic setup requires that the crystal be connected to electrodes - aluminum foil may be clamped to it, or something similar. The crystal might also be connected to a paper loudspeaker cone to help vibrations of the crystal couple mechanically to air for efficiency.
An audio amplifier capable of driving a loudspeaker should be able to produce some audible sound from your crystal. Alternatively the crystal could actually be used as a microphone if connected to a suitable preamplifier (audio mixing board perhaps): piezoelectricity is a reversible effect! Applying electricity to the crystal will make it vibrate, and making it vibrate will generate electricity.References: