Please quench my thirst for knowledge

Factual Questions
1

(also known as Whoa! 100 posts and it only took over a whole friggin YEAR…ahem…)

Just want to ask two questions about some stuff I’ve been thinking about recently. This is what I wondered about in my free time.
First of all, awhile back, I was at a Vietnamese restaurant with some relatives. Someone ordered a house beer (some Chinese thing I believe, not sake) and, finding it bitter, poured some Sweet n Low into it. It proceeded to soak the immediate area in bubbly fizz. What happened? Would that happen to any beer or was this a freak coincidence? I would of course experiment on my own, but I am both underage and minus any artificial sweetener…
Also, while sitting in traffic I see more and more school buses with annoying blinking lights on the roof. Why are they there? Visibility (on a yellow school bus??)? Or are they just there to make me glad I am no longer in public school?

2

The crystals of sweetener could act as loci for the gases in the beer (carbon dioxide?) to come out of solution, causing the fizzing and frothing. I think this would occur if any small solids were poured in, not just sweetener; salt or sugar or even sand would do the same thing. I believe this would happen with any carbonated beverage.

I think the blinking lights on the school buses are there to warn drivers to stop or proceed with caution. You might see the bus labeled with something like: “Stop when lights are flashing.”

3

As for the beer and bubbles, I expect that it’s the same principle at work as in carbonated drinks and boiling water. Bubbles generally form more easily when they have something to form around. The addition of the sugar particles into the beer gave all the dissolved gasses something to form bubbles around giving it a froth.
Try the same experiment with Coke, or water you heat in the microwave.

Be careful heating water in the microwave though as it may become superheated (heated beyond boiling temperature, but still liquid). If that happens the addition of sugar or a wooden spoon or anything could cause a whole bunch of bubbles to form at once, and maybe even explode from the container.

4

Cecil knows best

http://www.straightdope.com/classics/a2_043.html

5

On the school buses: Around here, there are yellow flashing lights that get put on when the bus is approaching a stop and while it is stopped with the door closed. Once the driver opens the door, the red lights start flashing (and the stop sign on the driver’s side is extended).

6

Are you talking about the purplish-white strobes on the roof of the bus? Those are for extra visibility in inclement weather (fog especially), and are indeed getting more common.

7

I don’t think the OP was asking about the yellow/red stop lights on the buses. Around here, too, there are buses with a white flashing light located on the roof. The flashing doesnt appear to change depending on if the bus is letting someone on/off or not, and IMHO, it doesn’t make the bus any more visible. I actually think that the light is further away than the bus sometimes! I don’t know what the light is for either, but I was just wondering this today myself!

8

Quoth TheNerd:

Urban legend. There is such a thing as superheated water, but you won’t produce it in a microwave in an ordinary container. You need some way of keeping the water at high pressure, as in a pressure cooker.

9

Chronos, I don’t know what you call it, but after Cecil did his column I tried it. I heated water in a ceramic cup, then quickly dumped in a handful of sugar and watched it bubble. First it was hot and no bubbles, then poured in the sugar and watched it go.

Wasn’t nearly hot enough to spray all over or explode. But if the glass had been more full, it could have spilled over the edge and onto, say, my hand. I was prepared and not holding the cup at the time.

10

I think what Chronos was saying is that the water in the microwave is less than 100°C. At high pressure, for example at the bottom of the ocean, you can have water (coming out of hydrothermal vents) that reaches 300-400°C, but is still liquid and not vapor. Now that’s superheated water.

11

Sorry Chronos

Microwaved water, however, heats up uniformly. Since there’s no convection, bubble formation is pretty limp. Without bubbles, the water heats as much as seven or eight degrees Celsius above boiling point without actually boiling, a process called superheating.

From Cecil http://www.straightdope.com/classics/a3_111.html

12

Regarding the light on top of the school buses: it’s a warning/safety thing, much like the revolving lights on tow trucks and snowplows - “large moving object - use caution”.

I had never seen a flashing light on top of a school bus until I moved south. The light flashes as long as the engine is on, whether the bus is moving or not. With the light, it is easy to identify the large object as a school bus not a truck or moving van, (hopefully) setting off a warning! in the brain - “Oh, a school bus. That means there may be children in the area. I should slow down and use extra caution.”

I happen to think this is a darned good idea, especially in the winter; in my county, there are students who have to catch the bus well before sunrise and ride for nearly an hour to get to and from school, sometimes getting home at about twilight.

13

This is not an answer to the OP, but I think that anyone who puts Sweet n Low in their beer should be beaten severely.

14

Thanks for the replies. About the Sweet n Low…well, that wasn’t me. Sounded like a disgusting idea too. But hey, anything to advance science. And also another reminder to self to continue putting the cocoa in the cup before adding the water like the nice all knowing box says.
And of course after I posted a friend commented on the school bus lights (I meant the strobe-like lights on the top of some buses these days) being there for nighttime and fog…still, I wondered if a strobe on top the bus was a good idea. It does I presume have headlights and tailights, so why the extra advantage of a light on top?

15

I have sacrificed one of my precious beers (a micro-brew even) to test the beer and sugar thing. In trying to make something that was at least palatable (it was not) I mixed instant cider and an amber ale. Fizzing par excelence resulted. I belive there is some universal force of the universe at work here. Two more beers and I’ll have it worked out.

Incidentally, a rather tragic example of distubing dissoved gasses happened in Cameroon. What is belived to be an earthquake disturbed Lake Nyos, which had a high concentration of dissoved CO2. The gas was released from the lake, rushed downhill (CO2 is heavier than air), asphyxiating about 1700 people.

16

Basically, as I stated in my post (did you read my post? It’s kind of buried among the sweetnlow and microwave posts.), the strobe light on top of the bus is a safety feature to catch your attention. (Did that work? You probably looked right at that word when you scrolled down to this post.) It’s something out of the ordinary, and you are going to react to it. As I stated in my post, a lot of kids have to catch the bus in the dark, especially with the days getting longer. Drivers do not realize that the buses are out as early as 6 am to get the kids from the rural areas, and even in the city and suburbs, drivers on the main roads are often so focused on getting to work or wherever that attention lapses.

It’s another warning sign besides the red/amber lamps and the swingout stop sign.

17

Okay, the school bus light has been beaten into the ground (unfortunately, while still on the bus), so I’ll leave it alone.

However, I can still respond to the bit about the Sweet ‘n’ Low.

The inside of a can of beer is fairly smooth. If you stick your finger in there and rub it around you can confirm this. You might also confirm that the mouth of the can can be fairly sharp, so I recommend you just take my word for it.

Now. Beer is normally carbonated. With kegs, the carbonation is either added beforehand (at the brewer) or at the tap. With bottles and cans, it is always added beforehand.

So. When you open a can or bottle of suds, it is soaked in carbon dioxide gas. That’s okay, doesn’t hurt anything, improves the taste, etc.

BUT. When you put something IN the beer… This gas is saturated. There is as much in the beer as the beer can contain. The only reason it stays dissolved in the liquid is because there is no specific place in the container for it to collect. The metal is smooth.

When you add sugar, sweet’n’low, sand, dirt, spit, most anything, alluvasudden, there are “nucleation sites”. What this means is that the CO2 can attach somewhere, and then more CO2 can attach to what’s attached. So instead of individual molecules occasionally colliding and MAYBE collecting enough to form a bubble, you hav CO2 molecules collecting and attaching at a point where it is very easy to form a bubble.

Since the can, bottle, or glass has very few of these sites, bubbles don’t form that often. Since those sites are at specific locations you’ll often see the bubbles rising from a specific point, in a line.

When you add a packet of sweet’n’low, you are adding thousands or millions of these sites, hence the thousands or millions of bubbles in a very short time, leading to a prodigious amount of foam.

You can get the same results with less expense by pouring a glass of coca cola and pouring in a packet of salt.

Since I’ve tossed back a few, I’ll be interested in the morning to see how coherent this post was. Feel free to question any portion of it.