this course is not popular in malaysia, and its hard to find job with it. thats why she got it easily

scgoh123, sagethesausage and BlueMuffin, can you answer the following questions? I got them from my Chemistry quiz sheet.

1.) Why does dry ice create fog?

2.) Why does your tongue sticks to a freezing metal pole?

PS: One doesn't necessarily require information or academic level of up to STPM to answer the above questions.

Methodology is commonly viewed as a combination of general principles and specialized techniques.

What kind of principles and techniques normally used by the ordinary people and the professionals?

Remember that the most important instrument in problem-solving must always be the mind of man.

I thought I can explain that using Physics!

Well sir, of course you can.

But, one thing remains unclear. Although the answer for the question no.2.) that was given by my teacher is the same as the one I found out from a lecturer, the explanations are somewhat different.

Put a metal spoon into the freezer for 30 min.

for no 1, when dry ice is pleced in water, sublimation is acceler
ated, carbon dioxide gas causes nearby water vapour to condense and form a thick white fog

1. Because dry ice is very, very cold. Dry ice is solid CO2, and from what we learn in Chemistry Chp 4, it sublimates into gas at atmospheric temperature. The gas cause a sudden drop in temperature. This drop in temperature causes tiny droplets of water vapour in the surrounding air to condense and form a visible fog.

2. Thermal conductivity of metal is very strong. It pulls heat much from your toungue much faster than the rate of your blood warming it up, causing moisture on your tongue to freeze, creating ice that latch your tongue to the pole.

This post has been edited by sagethesausage: Aug 17 2014, 10:11 PM

Actually, I did that when I was in primary 5. I put the spoon in the refrigerator for more than 3 hours. I placed it onto my tongue and it did stick on it. However, the result I got was kind of disappointing and the adherence of the spoon on my tongue was not as effective as the ones I saw on the television where a man's tongue adhered firmly to a metal pole. They even need to pour warm water onto the frozen metal to remove his tongue from sticking on it.

What intrinsic property that causes the ice to latch your tongue to the metal pole?

can anyone explain further on the moivre theorem, exponential, logarithm function, and how to plot graph for rational functions? any help is appreciated.

That's because a spoon only have a small amount of metal and thus warms up very quickly. If you want to recreate what you see on tv, try putting a hammer into your freezer hehe. Or maybe it's because freezer (0 degree celsius) is not cold enough? I don't really know what is the temperature required for intense tongue-latching to occur.

This post has been edited by sagethesausage: Aug 17 2014, 10:20 PM

You got me there Hahaha. Proving that I have not catch up on my reading and how 'intelligent' I am

Because water can take up any shape (or the shape of the container it's in). So when the moisture on your tongue freezes, the ice will form in the pores of your tongue and of the metal pole.

Ok, I'll admit that I don't know. Just talking out of my ass.

This post has been edited by sagethesausage: Aug 17 2014, 10:27 PM

Great, thanks for posting the answers!

In the question 2.), our tongue will freeze because it's coated with a layer of water, in this case it's saliva. So, it will form ice almost instantly if it's cooled at extremely low temperature and that causes our tongue to bond with the metal.

Also, since our body generate heat to some extent, why does the body can't be able to keep our saliva from freezing with the metal pole? It's due to the fact that our body doesn't generate sufficient amount of heat energy under a short amount of time, like you've mentioned. On the other hand, a metal such as the lamp post has a very high conductivity, meaning that it can transport heat away from our body rapidly. But, that's true only on one condition, the metal must be at extremely low temperature, or otherwise our tongue won't adhere firmly on it.

Now, if I were to take a wooden spoon or a metal post and juxtapose them to see which of these 2 objects are able to stick on my tongue, the answer will always NOT be the wood?

It's due to the fact that wood can't conduct heat from our body at a faster rate like the metal because wood or some substances that made from plastics have very poor thermal conductivity, meaning that these substances transport heat away from our body under a longer amount of time. Ergo, our body doesn't have a problem to quickly generate sufficient heat energy to replace the lost ones on our tongue. In other words, our tongue will only get cold when they are in contact with wood or plastics surfaces, but they surely won't freeze up.

Credits for the above explanations go to Prof. Phil Hultin.

But again, my Chemistry teacher said that there is a 'force' pulling the tongue towards the metal when the heat flows from a hotter region(tongue) to a colder region(metal) via conduction.

So, which is acceptable?

This post has been edited by RED-HAIR-SHANKS: Aug 17 2014, 10:37 PM

I think a professor is more credible than a teacher... I've never read anything about pulling force being produced when heat flows from hotter region to colder region (Disclaimer: I could be wrong as I don't study STPM Physics)

No and no. This is not about proving whose is catching-up to the syllabus or who is more clever. The reason on why I'm posting these questions is that I want to share this knowledge to everyone that doesn't necessarily require any detail knowledge of the Form 6 level. That was also why I intentionally pick these 2 questions instead of other questions in the quiz sheet that requires more in-depth knowledge of the Form 6 syllabus.

In fact, most of the students and friends that I know that are straight A scorers or even my one of my senior who obtained a 4.00 flat CGPA in her first term couldn't even come up with a brief answer on these kind of questions, and I'm not an exception too.

It's alright to be wrong, and we learn from our mistakes. This life is a perpetual path of learning.

Guess I shouldn't beat myself too much huh?
Ahhh thanks. It's refreshing to have a discussion among peers who don't talk in a condescending and supercilious manner. You couldn't imagine the likes that I have to deal with in my class... Everyone's out to get you. Thanks though, you made my day(night)

Wish I could help you but Maths T is my worst subject... Can't even remember a single thing from Chapter 1. If you ever need help in any other subjects barring PA I'll be happy to help though.

I'll have to leave this job to the other Maths T experts in this thread, sorry.

Learning for me, is one of the most interesting thing that I do, be it in aspects of academic or not. So, I don't see any reason on why we need to compare it with our classmates. Just so you know that I have a friend of mine who only got 1A in his UPSR, but he did make a shocking achievements by obtaining 9A's in his SPM examinations.

As you can see, time changes, and so does people. Today, you might beat him and that makes you the king. But, there is no guarantee that it will stay the same and the person that lost to you in the past might be capable of surpassing you in the future. So, don't bother compare your capabilities with the ones next to you. And even if you can't live without it, you can always compare with you yourself and ensure that you are better than you were in the past.

This post has been edited by RED-HAIR-SHANKS: Aug 17 2014, 11:22 PM