Category: Chemistry

Some Painful Truth

10/24/2022

Vicki Cobb
The Master Chef of Kids' Hands-on Science.

How well do you handle spicy food? Do you find food with a “kick” eye-watering and difficult to swallow? Or are you a real “fire eater;” nothing can be too hot?

A scientist, named Wilbur Scoville, figured out how to rank spicy food for hotness in 1912. The “heat” from peppers comes from a chemical called capsaicin (cap-say-sin). Pure capsaicin registers 16 million heat units on the Scoville scale. Zero is a sweet green, red or yellow pepper. A fresh, green Jalapeño (ha-la-pen-yo) is rated 2,500-8,000 units, a lot less hot than pure capsaicin.

The fact is that you don’t “taste” the heat. The sensation of heat comes from nerve endings in your tongue that respond to pain. Of course, these nerve endings are not just in your tongue. They are all over your body. So a good scientific question is: Can you “taste” hot sauce with, say, your wrist?

Check it out. Rub the inside of your wrist with a cut Jalapeño pepper or some hot sauce. Wait a few minutes. Feel the burn? Rinse off your wrist well with cool water.

Your tongue, of course, is much more sensitive than your wrist to many chemicals because it is always wet. Capsaicin, like a lot of other chemicals dissolves in water and reaches those nerve endings more quickly.

Another liquid that triggers your pain nerves in your tongue is soda. The carbon dioxide in the bubbles reacts with an enzyme in your mouth to form a weak chemical called carbonic acid. This acid fires the pain nerve endings in your tongue giving soda its “bite.”

How well can you tolerate this pain? Stick your tongue into a freshly opened glass of soda and hold it there. See how long you can keep it in the drink. One minute? Two minutes? Most people can’t last a minute. But maybe you’re tougher than that.

Some Mexican parents give their kids mixtures of sugar and red chili powder when they’re little to build up their tolerance for spicy foods. Do you think that people who love spicy food could also be champions at keeping their tongues immersed in soda? Design an experiment to find out at your next party.

Hot Stuff from Vicki Cobb on Vimeo.

atonguelashing from Vicki Cobb on Vimeo.

These videos were made from Vicki Cobb’s book We Dare You! She invites you to join her video project and make your own videos from her book and post them on the www.wedareyouvideos.com website.

Vicki Cobb is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.

MLA 8 Citation
Cobb, Vicki. "Some Painful Truth." Nonfiction Minute, iNK Think Tank, 17 Oct. 2017, www.nonfictionminute.org/the-nonfiction-minute/some-painful-truth.

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How to Extinguish a Fire with a Bag of Potato Chips

10/13/2022

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Vicki Cobb

The Master Chef of Kids' Hands-on Science

Ever taste a stale potato chip? If not, here’s how to make one:

If you have an open bag of potato chips lying around, you can use them. Otherwise open a new bag.
Put a few fresh potato chips in a glass bowl in the sunlight and wait a day or two.
Taste one of these exposed potato chips.
Compare it to the taste of a chip from a brand new bag.

Big difference, no? It’s enough to worry a potato chip manufacturer. There are two things that make a potato chip stale. Can you guess what they are? Okay, I’ll tell you: Air (specifically oxygen in the air) and light. So potato chip manufacturers know that if they want to keep their chips fresh, they have to remove oxygen and light. How do they do that?

Take a close look at an opened bag of potato chips. It is foil-lined to make it light proof. An unopened bag is very puffy because it is filled with a gas. This puffiness protects the chips from breaking. But the gas in the bag is not air, which is a mixture of about 20% oxygen and 79% nitrogen. It is air without the oxygen, so it’s mostly nitrogen.

You can prove this. Oxygen is needed for fire to burn. If the air around a flame is flooded with nitrogen, the flame goes out. So you can use the gas in a bag of potato chips to put out a candle. Here’s how:

Light a candle. (Make sure you have an adult help you since this trick involves fire.)
Cut off the corner of a new bag of potato chips.
Gently squeeze some of the gas from the potato chip bag near the candle flame. If you squeeze too hard, it’s like blowing the flame out. You want it to go out because the nitrogen in the potato chip bag is quietly flowing into the space around the flame.

Now you know how to extinguish a flame with a bag of potato chips. You have also proved that there is no oxygen in a potato chip bag! And you know why!

Now go educate some grown-up.

Before being flooded with nitrogen

After being flooded with nitrogen

Vicki Cobb’s best known book is Science Experiments You Can Eat. This is the new third revision published in 2016.

Vicki Cobb is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.

MLA 8 Citation
Cobb, Vicki. "How to Extinguish a Fire with a Bag of Potato Chips." Nonfiction Minute, iNK Think Tank, 2 Oct. 2017, www.nonfictionminute.org/the-nonfiction-minute/how-to-extinguish-a-fire-with-a-bag-of-potato-chips.

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Why You Can’t Defrost a Salad…Yet

5/2/2022

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Vicki Cobb
The Master Chef of Kids' Hands-on Science

At left in the back is a fresh spinach leaf that has been treated with trehalose, frozen and defrosted.. The droopy one has been frozen and defrosted without trehalose. It's what is giving us hope that we may soon be able to defrost a salad.

When it comes to preserving a fresh taste in food to be eaten at some later time, nothing beats freezing it. That was the discovery made by Clarence Birdseye in 1924. He had been working in northern Canada and noticed that fish caught by the native Canadian Inuits froze almost instantly in the frigid winter air. It was just as delicious when cooked and eaten months later as it was on the day it was fresh. Birdseye figured that if food was frozen quickly at very cold temperatures, large ice crystals couldn’t form to damage the food and make it mushy. His flash-freezing process made him very rich.

The problem isn’t so much the freezing of food as what happens when it’s defrosted. See for yourself. Stick a stalk of celery in your freezer. The next day defrost it. Want to eat it? Compare it to a fresh unfrozen stalk. The perky structure of fresh celery is destroyed by ice. Water has the very unusual property of expanding and taking up more space when it changes into ice than when in a liquid state. That’s why ice cubes float and frozen unopened soda cans bulge.   Expanding ice crystals destroy the cell walls of plants. Quickly freezing fresh food keeps the ice crystals smaller than slower freezing, but they are still large enough to destroy the cell walls of delicate vegetables like spinach or lettuce. But if you defrost frozen spinach from the supermarket it is beyond limp. So a salad you can defrost and serve as if it were fresh has seemed like an impossible dream.

Federico Gomez, a Swedish scientist, is working to change this. Like Birdseye he took a close look at nature, specifically at plants that stay alive in very cold climates. He discovered that they contain a sugar called trehalose (tree-HAL-ose) that works like a natural antifreeze. Could he find a way to get trehalose into spinach leaves? If so, would the trehalose protect the structure of the spinach and keep it crisp after defrosting? This picture shows the results. The leaf on the left was treated with trehalose. The one on the right was untreated. He froze and defrosted both. The treated leaf is as crisp as if it had never been frozen!

Just because there is success in a lab doesn’t mean a defrosted salad will show up on your dinner plate any time soon. But these results are enough to keep the research going.

Move over Clarence Birdseye!

This is a nice fresh, crisp piece of celery...

...and this is the same piece of celery after being frozen and then defrosted. Yuk!

Cobb has revised her classic book, Science Experiments You Can Eat. While doing her research, she came across this work of Frederico Gomez. She bought trehalose on line and soaked some slices of parsnip and zucchini in a trehalose solution, hoping that the sugar would be absorbed by the plant cells. But when she froze them and defrosted them, it didn't work. Dr. Gomez got the sugar inside the plant cells by removing some water from between the cells in a vacuum chamber, soaking the leaves in a trehalose solution (which moved the sugar into the spaces outside the cells) and then exposing the leaves with a mild electric shock to get the sugar through the cell walls. Vicki didn't have the equipment to do all this but she tried anyway. The book was published in 2016.

Vicki Cobb is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.

MLA 8 Citation
Cobb, Vicki. "Why You Can't Defrost a Salad...Yet." Nonfiction Minute, iNK Think
Tank, 11 01 2018, www.nonfictionminute.org/the-nonfiction-minute/
Why-You-Can't-Defrost-a-Salad-Yet.

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Gong Farmers: Their Crop Was ...Crap

4/13/2022

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Jim Whiting
The Running Encyclopedia

During the Middle Ages, “going to the bathroom” or “relieving oneself” meant using a privy. A privy typically consisted of a raised board with one or more openings cut in the middle where the users would sit. Their fecal matter would plop into large holes called cesspits beneath them. Over time, the cesspits would fill up and start overflowing. When that happened, gong farmers had to empty them.

“Gong” came from a word that means “going.” And the farmers “harvested” the accumulation of months or even years of “going.” To make sure all the foul material was removed, the workers would hop down into the pits, where the feces came up their waists or even higher. Because of the relative ease of getting them in and out, small boys were often employed. The cesspool contents were dumped into carts and taken to larger dump sites on the edge of town, where more conventional farmers would use it as fertilizer.

People in the Middle Ages rarely bathed. So gong farmers stunk. Really. Stunk. Because of their horrible stench, they were often restricted in where they could live. They were allowed to work only at night to spare their fellow citizens from seeing and smelling them.

Besides the horrible smell and probable lack of friends, gong farmers encountered specific occupational hazards. Decaying fecal matter could produce poisonous gases. At least one gong farmer stumbled into a cesspool he was cleaning and drowned. Violators of the rules for collecting the refuse and disposing of it were submerged in barrels up to their necks and placed on public display for hours on end.

On the other hand, gong farmers were well paid, often earning in a day what other workers might make in a week. They had another potential source of income as well. Careless crappers occasionally dropped rings or coins into the cesspits. Enterprising gong farmers combed through the mess with their bare hands in search of those treasures.

The advent of better sanitary methods in the 19th century ended gong farmers in many countries. However, it is still practiced in some areas of the world.

With only rats for company, a gong farmer empties his cart into the community pit

Gong farmers were only allowed to work at night, thus they were also known as night-men. The waste they collected, known as night soil, had to be taken outside the city or town boundaries.

Eighteenth-century flyer advertising the services of John Hunt, nightman and rubbish carter, showing two men carrying one of the pipes used to remove human excrement.

You can learn more about Jim Whiting with a visit to his website. He is an interesting fellow with an interest in music and sports and has written lots of books in both fields.

MLA 8 Citation
Whiting, Jim. "Gong Farmers: Their Crop Was ...Crap." Nonfiction Minute, iNK Think Tank, 15 Dec. 2017, www.nonfictionminute.org/Gong-Farmers.

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Some Painful Truth

How to Extinguish a Fire with a Bag of Potato Chips

Why You Can’t Defrost a Salad…Yet

Gong Farmers: Their Crop Was ...Crap

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