What happens when the purple anthocyanin is mixed with bleach?
The purple anthocyanin compounds in wild grapes change color when in contact with acids (turning reddish) and bases (turning more blue-green). Thanks to Kathryn Campbell for shooting the video.
How does swirling the open bottle induce a color change of the sports drink?
A variation of the classic blue-bottle experiment in which Blue Dye #1 (erioglaucine) is reduced by sugar to a colorless form. When the reaction is swirled, oxygen from the air reoxidizes the Blue Dye #1 back to blue, at least temporarily. CAUTION: THIS REACTION OCCURS IN VERY BASIC CONDITIONS, DO NOT DRINK!
How is the decomposition of acidic hydrogen peroxide catalyzed in this demonstration?
All 50 mL graduated cylinders contain 10 mL 3% H2O2, 3 mL 1 M H2SO4, and one drop of dish soap.
left cylinder: 1 half-inch rusty iron sphere added
middle cylinder: 8 quarter-inch rusty iron spheres added
right cylinder: 64 eighth-inch rusty iron spheres added
Estimated temp: 296 K
Estimated pressure: 0.992 atm
How does the bromocresol green indicator visually show the endpoint of the titration?
Titration of a weak base with a strong acid converts the bromocresol green indicator from blue to yellow.
What happens when a vitamin C tablet is added to an iodine/starch solution?
Time-lapse (about 35 min) of a Vitamin C tablet placed at the top of an iodine/starch solution in a graduated cylinder looks like a dark flame burning upside-down.
Why does the pen show up in dark ink on paper, but it faint yellow ink on the dollar bill?
Demonstrations of an iodine-based counterfeit detection pen and the reduction of iodine in starch with Vitamin C (ascorbic acid) in the palm of my hand.
How can paper chromatography be useful in a lab?
Paper chromatography time-lapse Mixtures: (left) green transparency marker, (middle) blue transparency marker, (right) black transparency marker
Stationary phase: coffee filter
Mobile phase: deionized water
Is this reaction endothermic or exothermic?
Catalytic (and very exothermic) decomposition of hydrogen peroxide to form oxygen gas and water in a plastic pumpkin. Soap was added to the peroxide solution to make a foam. CAUTION: Do not try this "elephant's toothpaste" demo variation - we had multiple protection measures in place. Special thanks to Ronnie Richardson-Matthews for running the reaction.
What is the salt bridge in this reaction?
Voltage produced from the reduction of copper oxide and oxidation of zinc metal on pennies. My hand serves as the salt bridge for this simple battery.
Why is polar water attracted to a charged balloon?
Polar water stream attracted to charged balloon.
Why does the “pumpkin” turn from yellow to red?
A glass "pumpkin" blushes from yellow to red when ammonia solution is added to its water suspension of curcumin (found in turmeric).
Why does the reaction differ when the tablet is combined with an acidic solution or with a basic solution?
Seltzer tablets containing citric acid and sodium hydrogen carbonate are added to (left to right) household ammonia, deionized water, and vinegar. The hydrogen carbonate ions in the tablets that are exposed to greater hydronium ion concentrations react to produce carbon dioxide more quickly. Thanks to Dannielle Wentzel for pointing out this effect.
Is photosynthesis a redox reaction? What happens in the reverse reaction?
Description of photosynthesis as a nonspontaneous redox reaction, where carbon dioxide, water, and energy combine to produce sugar and oxygen gas. The reverse spontaneous redox reaction, where sugar and oxygen gas combine to produce carbon dioxide and water, releases enough energy to make the light blink in the biofuel cell.
Do materials with higher surface area or lower surface area react faster?
Ten sheets of shredded paper (higher surface area) catch fire faster than ten sheets of stacked paper (lower surface area).
What causes the color change in Spackle?
Color-changing spackle is pink when it is wet out of the container, but turns white as it dries out. The pink color comes from phenolphthalein. Phenolphthalein is pink in basic conditions and colorless in neutral and acidic conditions, and adding a little vinegar (acetic acid solution) turns the pink spackle to white. In a separate experiment, adding water to dry spackle can turn it pink again, so it appears that the color change from pink to white might be largely due to the phenolphthalein drying out.
How do we know that the citric acid is the limiting reactant?
Wack A Pack balloons are balloons that self-inflate when they are struck hard. The impact breaks a pouch of citric acid solution (about 0.4 g citric acid in about 2 g total solution). The citric acid reacts with powdered baking soda (roughly 0.8 – 1.5 g) to produce carbon dioxide gas. The volume of the balloon produced is about 150 mL. It appears that the citric acid is the limiting reactant, as it can produce about 150 mL of gas if it reacts with excess baking soda. As demonstrated here, if all the baking soda was the limiting reactant and was reacted with excess acid, the volume of gas produced would be significantly greater.
How does this video demonstrate oxygen being removed from the bottle shown?
Time lapse showing powdered iron from disposable hand warmers removing some of the oxygen from the air in a plastic bottle and decreasing its volume.
How is the oxygen removal measured?
Powdered iron from disposable hand warmers removed some of the oxygen from the air in a plastic bottle and decreased its volume by about 14%, as measured by water volume displacement in a graduated cylinder. Air is about 21% oxygen.
Why does the crystal violet fade more quickly with 2 M NaOH than 0.02 M NaOH?
A 0.00002 M solution of crystal violet dye fades much more quickly as it reacts with 2 M NaOH solution than with 0.02 M NaOH solution.
How is LeChatelier’s Principle demonstrated in the following video?
When the temperature is increased for the reaction: heat + N2O4 = 2 NO2, the reaction shifts toward the products and produces more brown NO2 gas. When the temperature is decreased for the same reaction, the reaction shifts toward the reactants and produces more colorless N2O4 gas. This is consistent with LeChatelier’s Principle applied to an endothermic reaction.
How does the addition of aqueous ammonia solution affect the color change of the copper solution?
Addition of a small amount of aqueous ammonia solution to blue copper(II) sulfate solution initially produces light blue copper(II) hydroxide solid. Additional aqueous ammonia solution dissolves the copper(II) hydroxide to produce purple aqueous tetraamminecopper(II) ion solution. Minor correction: The concentration of aqueous ammonia solution was 1 M, not 0.1 M as stated in the video.
How do the plants generate heat? What are the advantages of this?
Forward looking infrared (FLIR) video of eastern skunk cabbage blossoms in late February. The plants consume some of their stored starch to generate heat. It is believed this helps the blossoms melt nearby frozen earth and volatilize compounds to attract insects to pollinate the blossoms. Caution: In some areas, these plants might be protected species or grow in fragile wetlands.
How does the shopping cart going over the barrier demonstrate kinetic energy with chemical species colliding?
A metal plate in a shopping cart corral (drop off area) resembles an activation barrier in chemical kinetics. A shopping cart will not cross over the metal plate unless it has sufficient kinetic energy. Chemical species colliding will often not react with each other unless they collide with sufficient kinetic energy.
What is an application of silicone?
Short description of the synthesis and cross-linking of silicone polymers, and a description of one application where a silicone polymer is used to synthesize and support palladium nanoparticles used as catalysts.
What happened when the gold chloride was heated? Why do you think that is?
Time-lapse of heating a bit of old gold chloride (AuCl3 ?) on a piece of quartz on a hotplate. Fun color changes, but I am not certain what color represents what. The resulting gold is not very shiny, except maybe at the edges of the spot. Note the purple and pink halo on the hotplate surface. I think gold nanoparticles formed when some of the decomposing material spattered off the quartz.
What does dropping Tic Tacs into a soda can do? Why?
Dropping Tic Tac Candies Into a Soda Can
A soda straw can adapter assembly is modified to drop Tic Tac candies into a can of soda. (Food coloring was also added to the soda.) The soda fountains up through the tube of the assembly
Mentos in Red, White, and Blue Sodas
Addition of Mentos candies to red soda, colorless soda, and blue soda.
Why does adding Mentos Candy to the soda with oil produce this effect?
Mentos Candy Into Soda Under Oil (Red White Blue Version)
Mentos candy into colorless soda under olive oil. Red and blue food coloring have been added to the soda for a bit of extra color. Special thanks to Tom Kuntzleman for showing me this demo.
Why does adding Mentos Candy to the soda bottle produce this effect?
Mentos Soda Fountain Through a Water Balloon Filling Assembly
A plastic tube assembly sold for filling fill multiple water balloons is attached to the top of a Mentos candy soda fountain launcher. Using this can produce a soda fountain that resembles a faucet or shower sprayer.
What is the purpose of the rusty BB’s?
The narrow straw is loaded with rusty BBs and held in place with a magnet, then a larger straw with a closed end is placed over the smaller straw.
Why do you think the solutions are foaming?
Red, White, and Blue Foaming Reactions (time lapse)
Time-lapse of a foam-producing reaction. This set of experiments is still in need of refinement so no details on this one...yet.
What causes the thermal paper to change colors throughout this demonstration?
Time Lapse of HCl Vapor-Treated Thermal Paper Changing Colors After Removal from Vapor Exposure
Thermal paper such as one might find in cash register receipts is placed in a closed jar and exposed to HCl vapor produced by a solution of concentrated hydrochloric acid. The paper darkens and turns reddish. This time lapse video (15 minutes condensed to 15 seconds) shows that when the paper is removed from the HCl vapor exposure, it turns dark gray and then adds a slight greenish tint.
How much energy does the Minuteman Missile carry?
Minuteman Missile at the Delta 9 Launch Site Near Wall, SD
View of a training Minuteman missile at the Delta 9 launch site near Wall, SD. The energy released by the single 1.2 megaton thermonuclear (fusion reaction initiated by energy from fission reaction) warhead that this missile could carry would be about 5 quadrillion Joules, which is well beyond the scale of the energies typically discussed in General Chemistry courses.
Why is there condensation on the bottom half of the tank, but not the top half?
Propane Level Showing in a Tank Shown by Condensation on the Tank
As propane in a tank is consumed, liquid propane typically evaporates to propane gas before it leaves the tank. The liquid propane remaining in the tank cools down as the most energetic molecules evaporate. This cooling is sometimes sufficient to condense water vapor from the air onto the outer surface of the tank, revealing the level of propane in the tank.
What happens to the chunks of dry ice when added to the tap water? Why?
Chunks of dry ice (solid carbon dioxide) are added to a tray of tap water containing universal indicator solution. As the dry ice sublimes to form carbon dioxide gas, some of it reacts with the water to form carbonic acid. In this time-lapse video, as the solution becomes more acidic, the indicator changes from green to yellow to orange.
What makes the handprint visible in this Thanksgiving-themed demonstration?
A solution of 70% 2-propanol (30% water) is sprayed on a gloved hand, which is then pressed onto thermal paper. The solution enables weak acid in the paper to react with the dye in the paper (normally heat is used to do this) and produces a dark handprint as the solution dries. The handprint here in this time-lapse video is decorated to make a hand turkey. Wear gloves to keep your fingerprints off the paper and to protect your hands from various chemical species in the thermal paper. It is a good idea to wash your hands after doing this and other demonstrations.
More information about thermal paper chemistry can be found at: https://www.chemedx.org/blog/thermal-paper-polarity-and-acidity-detector
Comparison of 9 V batteries immersed in deionized water and water saturated with magnesium sulfate. The higher concentration of ions in the magnesium sulfate solution makes it more electrically conductive, enabling the battery in that solution to more easily electrolyze water to form hydrogen and oxygen gas.
Comparison of 9 V batteries immersed in deionized water and water saturated with magnesium sulfate. The higher concentration of ions in the magnesium sulfate solution makes it more electrically conductive, enabling the battery in that solution to more easily electrolyze water to form hydrogen and oxygen gas.
Iodine and starch in a dollar bill and paper and reduction with Vitamin C on paper
Demonstrations of an iodine-based counterfeit detection pen and the reduction of iodine in starch with Vitamin C (ascorbic acid) on the pen mark on paper.
A solution of iron(II) sulfate (at left) is added to green tea (at right), turning it black as the polyphenols in the tea form complexes with the iron(II) ions. This chemistry is similar to that used in the production of iron gall ink, which has been produced for hundreds of years.
Wack A Pack balloons have limiting reactants
Wack A Pack balloons are balloons that self-inflate when they are struck hard. The impact breaks a pouch of citric acid solution (about 0.4 g citric acid in about 2 g total solution). The citric acid reacts with powdered baking soda (roughly 0.8 – 1.5 g) to produce carbon dioxide gas. The volume of the balloon produced is about 150 mL. It appears that the citric acid is the limiting reactant, as it can produce about 150 mL of gas if it reacts with excess baking soda. As demonstrated here, if all the baking soda was the limiting reactant and was reacted with excess acid, the volume of gas produced would be significantly greater.
Wack A Pack self-inflating balloons are placed on either end of a wire balancing across a pivot point. When the inflation of one of the balloons is initiated, the wire does not pivot, indicating that although there is a large volume change in the balloon, there is not a corresponding mass change in the balloon.
A hanging Wack A Pack balloon (out of its outer packaging) is activated while being viewed with a forward-looking infrared (FLIR) camera. The temperature of the citric acid solution at the bottom of the balloon decreases as the sodium hydrogen carbonate dissolves into the solution. The fizzing of the carbon dioxide bubbles is audible in the video clip.
A hanging Wack A Pack balloon is subjected to heat from the flame of a butane lighter. The flame weakens a small portion of the plastic balloon, which fails and then releases a burst of carbon dioxide gas. This gas release twirls the balloon as it hangs from a bit of dental floss.
Maple sap collecting
Tubes collecting sap from sugar maple trees at Camp Wokanda near Peoria, IL. Some of the water is removed from the sap by reverse osmosis and then by heating to produce evaporation. The boiling point of the resulting syrup is 103.9 degrees Celsius.