October 25 – Sheer Nonsense

Today’s factismal: The first nylon stockings went on sale in 1939.

Back in 1939, women had a big problem: they wanted to wear silk stockings but they couldn’t afford them. The price of a typical pair of silk stockings had risen by more than 50% in the past year alone, thanks to rising demand and embargoes on foreign goods. And even if she could afford the $0.69 ($11.26 in today’s money) that a pair of stockings cost, a woman was likely to see her investment ruined the first time that she wore them. Fortunately, chemistry was about to come to the rescue.

Artificial silk had been known since 1855 when nitrocellulose (aka guncotton or “oops! I blew your legs off”) was turned into fine, extremely flammable threads that became known as “mother-in-law’s silk”. The process was further refined into the creation of rayon from sawdust in the early 1920s, but the threads were coarse and irregular. So scientists searched for an alternative and finally found it in 1935. The nylon silk that they produced was first used to make bristles for toothbrushes; once the process had been refined enough to create long fibers, they started to manufacture stockings, parachute cloth, and other fabric goods.

A war poster encouraging recycling silk and other scarce goods (Image courtesy Truman Library)

A war poster encouraging recycling silk and other scarce goods
(Image courtesy Truman Library)

Their discovery came just in time as many of the traditional sources for rope (hemp from Indonesia), tires (rubber from Indonesia and Thailand), silk fabric (silk from China) and other materials had been embargoed due to concerns about the war that had begun. Thanks to their work, the US was able to substitute synthetic materials for the natural goods; today, many of those synthetic materials are not only still used but often preferred due to their superior quality and strength. If you’d like to learn more about the chemistry behind nylon and other synthetic fabrics, then head on over to Chemspider:
http://www.chemspider.com/

October 23 – We Are All Starstuff

Today’s factismal: There are about as many atoms in 5 1/2 ounces of oxygen as there are stars in the universe.

If you had been a chemist in the 1800s, you would have had a real problem. You knew for a fact that oxygen plus carbon would make water(H2O), but you would be able to say how much oxygen or how much hydrogen was needed to leave nothing but water in the reaction chamber. Sometimes you’d have oxygen left over and sometimes you’d have carbon left over and you’d always have a big mess. It was uncertainties like this that kept chemistry from being an exact science.

The reason that chemistry was an uncertain science was because the number of oxygen atoms in a pound of oxygen is different than the number of hydrogen atoms in a pound of hydrogen. (This is why Mark Whatney blew up the lab in The Martian.) Because chemistry takes place on the atomic scale, you couldn’t just add two pounds of hydrogen to one pound of oxygen and get nothing but water; you had to find some way of scaling the weight (or, more appropriately, the masses) of each chemical so that you’d be adding the right number of atoms. Fortunately, a scientist by the name of Avogardo pointed the way.

Avogardo (or “Avocado” as he is known to all freshman chemistry students) had the bright idea in 1811 that the volume of space taken up by a gas at a given pressure and temperature might be related to the number of atoms in that gas; based on that, he and other scientists were able to derive the relative atomic weights of the elements. It took the chemists nearly a century, but by 1909, we had a periodic table that listed the atomic weight of each element. That allowed us to know exactly how much of each to add in order to get reactions that worked perfectly every time.

There are a mole of stars in the universe (Image courtesy NASA)

There are twenty moles of stars in the universe
(Image courtesy NASA)

Avogardo and the chemists who came after him called the standard amount of stuff a mole (short for “molecular volume”). And, because it was Avogardo’s bright idea that made it all possible, the number of atoms (or molecules) in a mole is known as Avogardo’s number. And it is a mighty large number – there are 6.02 x 10^23 atoms of oxygen in 16 grams (one mole) of oxygen. To give you an idea of how many atoms that is, just go outside tonight and take a look at the night sky. If you were to count every star in every galaxy in the universe, there would be about 10^24 stars. So there are as many atoms of oxygen in ten moles of oxygen as there are stars in the mole of the universe!

Chemists celebrating Mole Day (Image courtesy ACS)

Chemists celebrating Mole Day
(Image courtesy ACS)

In honor of Avogardo’s discovery, today is Mole Day (because it is 10/23 – get it?). So take part in a mole day celebration somewhere. Go eat a mole cake and drink some mole juice. And then make a un-moley mess, just so you can appreciate why chemists were so happy to become an exact science!
http://www.acs.org/content/acs/en/education/students/highschool/chemistryclubs/activities/mole-day.html

October 31 – Time To Prey

Math is often called the language of science. And the beautiful thing about that language is that it says the same thing whether you are working in chemistry or biology. Peter and Daniel will learn that as they discover why vampires can’t be real!

It was a bright, sunny fall afternoon. The houses were all decorated with pumpkins, mummies, and ghosts. The sky was clear and the air was crisp with the promise of a cool, clear night just perfect for trick-or-treating. Even better, the sidewalks were piled high with leaves that Peter and Daniel ran through on their way to the school’s annual Fall Festival.  The crunch of the leaves and the smell of the air promised great things to come and both of the boys were looking forward to the candy that they would collect that night. Both were in their costumes. Peter had on the cape, fangs, and slicked back hair of a vampire while Daniel had decided to go as a mad scientist, complete with labcoat, black gloves, and goggles.

“It sure is a shame that Mary couldn’t come,” Daniel said after crunching thourgh a particularly large pile of leaves. “Her costume was great! I love Doctor Who.”

“Yeah, she even had the little K-9 on a chain to tow behind her,” Peter replied. “But her dad is pretty strict; if your homework isn;t done, you don;t get to play.”

“Maybe that’s why she gets such good grades.” Daniel felt sorry for Mary; his dyslexia made studying a chore so he knew how it felt to miss a bright afternoon.

“You should talk, Mr. Brain!”

“That’s Dr. Brain to you!”  The boys laughed and turned into the school grounds. There at the entrance to the gymnasium was their favorite teacher, Mr. Medes; for the holiday, he was wearing insect wings and a pair of antennas but had painted his face grey and green.

“Hi, Mr. Medes!” the boys chorused. Then Peter asked “I don’t get it. What are you supposed to be?”

“I’m a zombee,” Mr. Medes replied. As the boys groaned at the pun, he explained. “There is a fly that lays its eggs inside of bees. The larva eats the bee’s brain and takes over, creating what biologists call a zombee.”

“So there really are zombies?” Daniel said. “Cool!”

“Are there really vampires, too?” Peter asked.

“Well, there are a lot of animals that drinkt he blood of other animals. There’s the female mousquito who needs the blood to make her eggs.There’s the hagfish, which rasps a hole in other fish with its tongue and sucks their blood. And then there’s the vampire bats; all three species live off of the blood of others. But if you mean creaturees like Dracula, then the answer is no; there can’t be.”

“Why not?” Peter insisted. “If we can have real live zombies that eat brains, why can’t we have real live vampires?”

“Because there would be too many predators and not enough prey,” Mr. Medes replied. “Here, let’s go inside and we’ll do an experiment to show you what I mean.”

At that the boys perked up. They both wanted to be scientists and doing  experiments was one of their favorite things. They quickly followed mr. Meddes inside the gym and over to a table.

“Have a seat while I grab some apparatus from my lab,” Mr. Medes said. “I’ll be right back!”

As the boys waited, they speculated on what the experiment would be.

“Maybe he’s got some blood for us to look at,” Peter said. “That would be cool.”

“Nah,” Daniel replied. “It has to be neater than that; I’ll bet he’s got some real, live zombees for us!”

In just a few moments, Mr. Medes returned with a piggy bank in his hands. The boys stared at him, confused.

“A piggy bank? What does that have to do with vampires?” Peter demanded.

“Patience,” Mr. Medes advised. “We’re going to be doing a model of how vampires would interact with humans. And since we can’t use real humans and real vampires in our experiment, we’ll substitute something else. The people will be pennies and the vampires will be nickles. We’re going to need about 100 pennies and 100 nickles.”

With that, he pulled the cork from the bottom of his piggy bank so that the change spilled out. Quickly the three of them sorted the coins and piled up the necessary change. Pouring the rest of the money back into the piggy bank, Mr. Medes began explaining the experiment.

“Here’s the way it works,” he began. “There are twenty vampires, represeented by our twenty nickles. And there are fifty people, represented by fifty pennies. The remaining coins will come into play later. The vampires go first. Peter, you’ll gather up the nickles and shake them in your hands, then drop them on the table. The nickles that land face up get to eat; you’ll take away one penny for every face up nickle because the vampire just killed a person. And then you’ll add a nickle for every person eaten so your vamprie population will grow.”

Peter picked up the nickles and shook them over the table before letting them drop. When they landed, he quickly sorted them into five that landed face up and fifteen that landed face down. Peter then took eight pennies from Daniel’s pile and added eight nickles to his.

“Hah!” Peter said in his best Transylvanian accent. “You people sure are tasty!”

“OK, now it is Daniel’s turn,” Mr. Medes said. “Shake your pennies and then drop them just like Peter did with his nickles. When they land, set the face up ones in groups of four; for every group, you get a new penny.”

Daniel quickly shook up the pennies and let them fall. Sorting them, he found that he had twenty-four face up pennies, so he added six pennies to his pile.

“Hah right back!” Daniel said. “We added more people than you ate!”

“So you both know how to play, right?” At the boys’ nods, Mr. Medes continued. “Then here’s the question: can vampires exist if they eat people?”

“Sure,” came Peter’s response. “My vampires ate eight people but they added thirteen. So we can eat forever and there is no reason that we can’t exist.”

“I dont know,” Daniel said. “You added almost as many vampires as we did people. If you grow too fast or we don’t grow fast enough, we might all get eaten.”

“Well, there is only one way to find out for sure,” Mr. Medes said. “Let’s do the experiment!”

What do you think will happen? Do the experiment!

 

 

The boys eagerly nodded and started flipping coins. In Peter’s next round, he had eight face up nickles, so his vampires had eaten eight people and gained eight new members. Daniel did well that round and again had twenty-four face up pennies, so he had six more people added.

“Hey! Not so hungry!” Daniel said.

“We’ll see about that!” Peter crowed. His face fell when just three nickles landed face up but he quickly brightened when Daniel could only muster five face up pennies. “You people sure are slow; you just added one new one!”

As the game continued, the boys started to add sound effects and other silliness. Peter began to chuckle like a B-movie Dracula each time his vampires ate a person. And Daniel cried out “My baby! My baby!” each time he gained a new penny.

Peter gained fourteen vampires in the next round while Daniel only added nine people. And the following round was even more disastrous; sixteen new vampires were created but only four new people. For the first time, the vampires outnumbered the people. The end came swiftly. In each of the next three rounds, far more people were eaten than were born and the vampire population exploded. In the final round, there were nearly a hundred vampires and just thirteen people.

“Wow!” Peter said. “I didn’t think that would happen!”

“Yeah,” agreed Daniel. “For awhile it looked like the people could stay alive but then, BOOM!”

“What you two have just seen is what is known as a population collapse,” Mr. Medes said. “Biologists like to study this because it can tell us things such as how long a disease outbreak will last or how many fish we can take from an area. And, as you’ve seen, it shows that vampires simply cannot exist.”

“How can this one experiment show so much?” Daniel asked.

“Well, the experiment looks pretty specific but when you express it in math, it becomes general. The math doesn’t care whether you are talking about the number of people who catch a disease like vampirism or the number of fish that get caught or the amount of chemicals left in a reaction; it works equally well in all situations,” Mr. Medes explained. “That’s why we say that math is the language of science. It helps us take what we learn in one area and apply it in another.”

“Wow,” Daniel said. “That’s cool.”

“It sure is,” Peter said. “But how did we discover that we could use math to talk about vampires?”

Mr. Medes chuckled. “Actually, Lotka was trying to describe a chemical reaction when he came across this idea. He used math to describe how the reaction happened and discovered that sometimes the solutions led to never-ending chemical reactions. He then applied the idea to biology and created what we call the predator-prey relationship. In our experiment, the vampires are the predators and the humans are the prey. Because the vampires always grow in population, they will always end up eating all of the prey and the humans will always be wiped out.”

“Cool!” Peter said. “So that’s why you said that vampires couldn’t exist. We still have people -”

“Which means that vampires haven’t eaten us all and the only way that they wouldn’t do that is if they don’t exist!” Daniel finished.

“The neat thing is that we do have something very like a vampire,” Mr. Medes said. “Every year, it attacks the human population and tries to convert as many people as possible into its slaves. This model helps groups like the CDC predict just how bad this year’s attack will be.”

“Really? What is it?” Peter asked.

“The flu! Simple diseases like the flu behave a lot like vampires,” Mr. Medes explained. “The only differences are that you are only turned into a flu monster until your body can get better and that we have a vaccine that works against it much better than garlic works on vampires. But it still builds up every year about this time, infects a lot of people, and then has a population collapse when it runs out of victims. And speaking of victims, I think I see a new one over there!”

Peter and Daniel turned to look where Mr. Medes was pointing. In the doorway was Mary, complete with a long scarf, floppy hat, and long coat. Peeking out from behind her was a model of K-9.

“Mary!” the boys chorused. Eagerly, they ran over to bring her into the party and tell her about their new experiment.

 

 

 

September 23 – Hole Lotta Trouble

Today’s factismal: The ozone hole stretched to cover a city for the first time fifteen  years ago.

One of the great successes in pollution control was the 1992 international treaty banning the use of chlorofluorocarbons (CFCs) due to their effect on the ozone layer. Following the signing of the treaty, nations were required to change their refrigerators and hairsprays so that they didn’t use CFCs; the only exceptions were for national security. So with the pollution stopped, the problem was solved, right?

2009 Ozone Hole (Image courtesy NASA)

2009 Ozone Hole
(Image courtesy NASA)

Wrong. The problem with pollution is that it doesn’t stop doing harm just because you’ve stopped putting more trash into the atmosphere. You still have to deal with all of the junk that was put into the atmosphere before you stopped. Some environmentalists call this the “teenager’s room problem”: sure, your kid has gone to college and left his room empty – but you still have the ten years of empty soda cans, candy bar wrappers, and dirty laundry piled in the corners that need to be cleaned out before it can be turned into a sewing room. And that’s where we are with CFCs in the atmosphere. We’ve stopped adding them but we still have to wait for the ones in the air to break down and go away. And, until they do, we will have problems.

This year's ozone hole (Image courtesy MACC)

This year’s ozone hole
(Image courtesy MACC)

In 2000 we saw one example of the sort of problem we’ll have; the ozone hole grew to cover an area three times the size of the continental United States. It got so large that it covered all of Antarctica and part of South America, including the city of Punta Arenas. For two days, the residents were exposed to more UV radiation than normal. Though they haven’t reported much in the way of side effects that is because UV damage is a long-term problem (e.g., skin cancer, glaucoma) caused by a short-term exposure. Fortunately, that was the largest that the ozone hole has ever gotten; since then it has shrunken considerably.

Of course, a hole in the ozone layer isn’t the only problem we’ve got. If you’d like to help monitor air quality, then why not join NASA’s Citizens and Remote Sensing Observation Network Air Quality project?
http://terra.nasa.gov/citizen-science

June 6 – Rust Bucket

Spring brings many joys – flowers, soft breezes, and the first bicycle rides of the year. But what happens when you forgot to oil your bike before putting it away – and what does that have to do with the furnace that kept you warm all winter long? Join Peter and Daniel as they discover the answer in today’s Secret Science Society adventure!

 

There is little more frustrating than being forced to clean up your own mess. And there is nothing more necessary. So that’s what Peter was doing; with a wad of steel wool in one hand and a rusty bicycle chain in the other, he was trying to remove the rust that had spread like a fungus on his bike and kept him from being able to ride it. Peter was hard at work when he heard what sounded like a motorcycle pull up behind him. Turning around, he saw his friend Daniel stop on his new bicycle, complete with a playing card stuck in the spokes to make the motor sound.

“Hey, Peter!” Daniel said. “I thought we were going to go on a ride!”

“So did I, until I tried to ride my bike this morning,” Peter replied. “This dumb chain is all rusted and won’t turn properly. And you know my mom – ‘It’s your mess, so you get to clean it up!'”

“Well, that’s no fun. How about I help you so we can go riding? I still don’t know the area as well as you and Mary do,” said Daniel.

“Deal!”

The two boys started to work on opposite ends of the chain, flexing the links and scrubbing away the rust wherever it kept them from moving. When one of them had finished with a link, he’d squirt a little oil on it and move to the next one. As they worked, they talked. Naturally, the main topic was the problem of the rust.

“What happened?” Daniel asked. “Why did your chain rust up?”

“I don’t know,” Peter said. “The last time I rode it was when we went out right after that snowstorm in January.”

“That’s right,” Daniel said; “you wanted to see if you could make a bike ramp out of snow.”

“Yep. We piled all that snow up into a beautiful ramp and then I just smashed through it. I think it was because the snow trucks had already been by spreading salt on the roads. You know how mushy that makes snow.” At Daniel’s nod, he continued, “so I rode back to my house and left the bike in the garage. It was fine when I left it. I wonder why it rusted?”

“You just answered your own question,” a high, bright voice answered him. “You set your bike on fire and left it to burn.”

Turning around, the boys saw Peter’s mother in the door of the garage.

“I wanted to see how you were getting on with the bike,” she said. “But it looks as if you still don’t know how to keep this from happening again.”

“Yeah,” said Daniel. “Why did his bike rust when mine didn’t? I rode out there with him and put my bike back in my garage, just like he did.”

“Did you do anything before you put your bike away?” Peter’s mother asked.

“Yeah, I washed it down with water and then put oil on the chain and axles. ” Daniel turned to Peter and asked “Didn’t you do that?”

“No, that never made any sense to me. Why wash the bike? And why put oil on it afterward?”

“The answer to that is simple,” his mother replied. “But you’ll have to see it to understand it. Stay right there while I gather some supplies and we’ll do an experiment to show what happened to your bike.”

The boys sat up eagerly. Doing experiments was one of their favorite things and it would give them a break from the tedious chore of cleaning the bike. Just a moment later, Peter’s mother came out with a book of matches, a leftover candle from a birthday cake, and three pairs of sunglasses.

“What are the sunglasses for?” Peter asked.

“We’re going to do some chemistry,” his mother replied. “In a real lab, we’d have special safety goggles to keep the chemicals from getting into our eyes. We don’t have the safety goggles, but sunglasses are almost as good; they keep stuff from splashing into your eyes and are stylish to boot.”

She handed each of the boys a pair of sunglasses and put on her own set. Once they had all donned their sunglasses, she lit a match and used the flame to soften the bottom of the candle then mashed the candle down onto the concrete garage floor.

“There,” she said. “That will keep the candle in place for our experiment. When I strike a match, what do we get?”

“Fire,” chorused Daniel and Peter.

“And when I put the lit match to the candle, what do we get?” she asked, putting deed to word.

“More fire,” said Peter. “But what does this have to do with my bike?”

“Hand me some of that steel wool and you’ll see,” she replied. “What will happen when I put the steel wool into the flame?

“It will get hot and maybe glow,” said peter.

“Hold it,” Daniel interrupted. “Remember that she said you left your bike to burn. Maybe the steel will burn!”

“There’s only one way to find out,” Peter’s mother said. “Ready?”

What do you think will happen? Do the experiment!

 

 

 

 

 

 

 

Peter’s mother stretched out the steel wool so that a few, wispy strands stuck out and then put them into the candle’s flame. As the boys watched with astonishment, the steel wool caught fire and started to burn, dropping glowing embers of molten steel onto the concrete floor.

“That is so cool!” Daniel shouted. “But what’s going on?”

“What we’ve done is speed up the process that makes rust,” Peter’s mother replied. “When iron meets oxygen, they swap electrons; that binds the two together in a process that the chemist calls oxidation and the rest of us call rusting. The same thing happens when the carbon in the candle wick meets oxygen; the chemist still calls it oxidation but we call it fire.”

“So a rusting bridge is really on fire?” Peter asked. “That’s weird.”

“Weird but true,” his mother said. “And it’s not just bridges. Even diamonds are slowly oxidizing; Antoine Lavoisier even set a diamond on fire in 1772.There are ways of speeding up the reaction. One is by adding heat; most chemical reactions go faster when the temperature goes up.”

“Is that why the steel wool caught fire in the flame?” Daniel asked.

“That’s part of it. We also made the steel very thin which exposed more of it to the oxygen in the air and that helps, too. And another way to speed things up is by adding a catalyst, “seeing their puzzled looks she added “that’s a chemical that helps a chemical reaction happen but isn’t part of the reaction. For rust, one of the most common catalysts is salt.”

“How can salt help something burn?” Peter asked.

“The salt dissolves in water into sodium and chlorine ions. Those act sort of like little ferryboats, bringing more oxygen to the iron in the steel. That speeds up the reaction. So if you wash off the salt, like Daniel did…”

“Then the catalyst is washed away, Peter said. “But what does the oil do?”

“It keeps the oxygen in the air from getting to the iron, so the chain can’t rust. And that is why Daniel can ride his bike today while you are stuck cleaning yours,” she added.

“There’s just one way to fix that,” Daniel said. “Let’s get back to de burning this bike!”

And with that, the two boys bent to their task, happy with the knowledge that they wouldn’t have to do it again because they now knew how to keep their bikes from burning.

 

April 18 – Soda Pops!

The only thing better than science is science that ends up making a huge mess. In today’s installment of the Secret Science Society, Mary, Daniel, and Peter discover exactly why candy plus soda pop makes such a big mess in Soda Pops!

 

As was normal for a Saturday morning, the Secret Science Society was in the backyard, making a mess. And the mess was everything that they had hoped it would be. Taking turns, Mary, Peter, and their friend Daniel would each open up a bottle of soda and then drop several small candies into it and quickly jump back to avoid the geyser of foam spewing out of the bottle.

“This is great!” Peter enthused. “I wish we had more soda!”

“That would be fun, but I wish we knew why it worked,” Daniel said.

“Me, too,” Mary replied. “Why does adding candy to soda make it spurt out like that? A scientist would know how to figure it out!”

At that moment, a voice from behind them called out “Then it is a good thing that you are all scientists, isn’t it?”

“Hi, Mom!” Peter said. “Taking a break from the cosmos?”

“Yes; I’ve found enough new planets for this week.” Peter’s mother studied planets around other stars and did most of her work at home. “I decided to come out and see what all the squealing was about.”

“We’ve been making soda fountains,” Mary said. “But we can’t figure out why it happens.”

“Well, let’s think about this,” Peter’s mother replied. “What goes into the reaction?”

“Carbonated soda and candy,” Daniel said.

“And we get foam and a lot of carbon dioxide out,” Peter added.

“OK, so we have to decide what it is about the candy that makes the carbon dioxide come out so quickly. What is the candy made up of?”

“It is mostly sugar with some mint flavor,” Mary said.

“And is the candy smooth or is it rough?”

Daniel peered closely at one of the candies in his hand. “It is sort of rough on the outside; there are lots of little bumps and holes on it.”

“Then we’ve got three possibilities,” Peter’s mother said. “First, it could be that the mint oil makes the reaction happen. Second, it could be that the sugar makes it happen. Third, it could be that the candy’s rough outside makes it happen. How can we find out the answer?”

“We could put a little oil into a bottle of soda,” Peter said. “If it makes the soda fountain out, then we’ve found the answer.”

“And we could try adding sugar to soda,” Daniel added. “If it makes the soda fountain out, then we’ve found the answer.”

“And we could add something that isn’t sugar but looks like it to the soda,” Mary concluded. “If the soda boils out then we know that it isn’t sugar that makes it go. But what has rough edges like sugar?”

“Salt does,” Peter said. “Let’s try it and see what makes the soda go!”

Eagerly, the three ran into the kitchen to gather up the supplies that they’d need. Daniel grabbed a bowl of sugar. Mary picked up a salt shaker. And Peter rummaged in the pantry until he found the oil. The friends then went back outside to run their experiment.

What do you think will happen? Do the experiment!

 

 

 

“Me first!” Peter said. He grabbed a soda bottle and took off its cap before setting it back on the ground. He carefully poured a little oil into the bottle and moved back.

“Nothing’s happening!” Daniel said. “It must not be the oil in the candy. Let’s try the sugar.” He opened a second bottle of soda and set it on the ground. He poured in some sugar and jumped back to avoid the rush of foam. “Aha! It’s the sugar!”

“Don’t jump to conclusions,” Mary said. “Let’s see what happens with the salt.” Mary took her turn opening a bottle of soda and then added salt to it. Again the soda fountained out of the bottle.

“So it isn’t sugar that makes it work,” Peter said. “I guess we should have known that because soda with sugar doesn’t spray out of the bottle.”

“Not unless you shake it up,” his mother agreed. “What happened is that both salt and sugar have a lot of rough edges; you can see them in a magnifying glass if you look. Those edges give the carbon dioxide a place to come out of solution.”

“Neat!” Mary said. “So anything with rough edges will make it work?”

“That’s right,” Peter’s mother replied. “If you look carefully at a glass with soda in it, you will see that there is often a stream of bubbles coming from a place on the glass. That’s where the glass has a small crack or a bit of something stuck on it. Scientists call those nucleation points. The more nucleation points there are, the more gas that can come out of solution.”

“But why do the bubbles come out at the edges?” Daniel asked.

“The exact reasons aren’t known yet,” she replied. “We know that part of the reason is because water molecules like to stick together; we call that surface tension. At a nucleation point, the water sticks to itself and not the glass or sugar or whatever. But the gas doesn’t stick together, and fills the gap. That pushes the water back a little, which lets more gas into the area. The reaction feeds on itself and you get a bubble that is too big to stay in place so it floats up and a new one starts. Do it fast enough by having lots of nucleation points and you get…”

“A soda fountain!” Mary exclaimed.

“OK,” Daniel said. “That makes sense. But why does diet soda work better?”

“That’s because of another effect,” Peter’s mother explained. “The sweetener in diet soda makes the water molecules stickier so that they make strong bubbles. That lets the foam hold together, which makes it go higher. But you could do the same thing by adding some glycerine and soap to a regular soda.”

“Yuck! I sure wouldn’t want to drink that!” Mary exclaimed.

“Me neither!” Peter’s mother replied. “But I would like to have some fun.”

Grabbing the candy, she turned to the soda to make her own fountain.

October 24 – Fine As Silk

Today’s factismal: The first nylon stockings went on sale in 1939.

Back in 1939, women had a big problem: they wanted to wear silk stockings but they couldn’t afford them. The price of a typical pair of silk stockings had risen by more than 50% in the past year alone, thanks to rising demand and embargoes on foreign goods. And even if she could afford the $0.69 ($11.26 in today’s money) that a pair of stockings cost, a woman was likely to see her investment ruined the first time that she wore them. Fortunately, chemistry was about to come to the rescue.

Artificial silk had been known since 1855 when nitrocellulose (aka guncotton or “oops! I blew your legs off”) was turned into fine, extremely flammable threads that became known as “mother-in-law’s silk”. The process was further refined into the creation of rayon from sawdust in the early 1920s, but the threads were coarse and irregular. So scientists searched for an alternative and finally found it in 1935. The nylon silk that they produced was first used to make bristles for toothbrushes; once the process had been refined enough to create long fibers, they started to manufacture stockings, parachute cloth, and other fabric goods.

A war poster encouraging recycling silk and other scarce goods (Image courtesy Truman Library)

A war poster encouraging recycling silk and other scarce goods
(Image courtesy Truman Library)

Their discovery came just in time as many of the traditional sources for rope (hemp from Indonesia), tires (rubber from Indonesia and Thailand), silk fabric (silk from China) and other materials had been embargoed due to concerns about the war that had begun. Thanks to their work, the US was able to substitute synthetic materials for the natural goods; today, many of those synthetic materials are not only still used but often preferred due to their superior quality and strength. If you’d like to learn more about the chemistry behind nylon and other synthetic fabrics, then head on over to Chemspider:
http://www.chemspider.com/