Thursday, April 30, 2009 ; Condensation
Dear pupils,
I've mentioned that condensation is the hardest section in the topic "water".
Some of you are still shaky over the concept. I'll just places a few notes about condensation here:
1) Condensation is the process whereby warmer water vapour becomes tiny water droplets on a colder surface.
2) Condensation happens at any temperature. The bigger the difference in temperature between water vapour and the cold surface, the higher the rate of condensation (more water droplets)
3) Condensation involves heat lost by water vapour to the cold surface.
4) Condensation involves the change of state of water from gas (water vapour) to liquid (tiny water droplets).
5) Water vapour and steam cannot be seen. They are colourless.
6) The white mist we see coming out of kettle with boiling water or the breath of people in very cold countries are actually water droplets, not steam or water vapour.
7) The white mist comes from water vapour which condensed to form water droplets in the air. The tiny water droplets is also evaporating very rapidly to the atmosphere.
8) Clouds are formed from condensation. So, clouds are made up of tiny water droplets.
Ask me questions on water or other Science related topics under "comments" if you have any.
Posted by Mr Wan
posted by Allan at
11:08 PM
28 Comments:
thank you Mr. Wan fer this...=) but I want to ask something... hope you won't mind._. what is atmosphere??? what is oil erosion??? the oil erosion is on the chapter about water-a precious recource... if you dun want to answer a lame question like that... I understand...=)
...Michelle...=)
Great questions!
atmosphere refers to the thin layer of air surrounding Earth.
It is mostly used to describe the "air" up in the sky. eg "water vapour condenses into clouds in the atmosphere".
For soil erosion, it refers to soil being washed into rivers when trees are cut. The roots of trees hold soil firmly, so cutting of trees causes soil to be eroded (washed away) to rivers and streams.
When soil enters the water, it causes the water to be murky or muddy. This prevents light from passing through water and so water plants cannot make food as there is no light.
I'll do up some notes on "water is precious" for 5C and 5D.
thank you sooo much Mr. Wan fer the answers!!!! i NEVER thought that I will ask good questions... =) Xp... haha!
...Michelle...=)
P.S. If I more questions, good or bad, I will ask you!
hmm... I think I have one more question but it is not on condensation! you said that when ice melt, the ice is 0 Degrees Celcius, is the water (the water is the ice that melted to liquid)also 0 Degrees Celcius??? In my SC notebook, I wrote that the water is also 0 Degrees Celcius. I REALLY want to know why. if you dun want to answer a lame question that had gone through before, I will try to ask my friends for help! thanks fer the answer fer the 2 questions!=)
...Michelle...=)
Basically, for pure ice, the highest temperature it can reach is zero degree Celcius. That's why it's called the melting point.
Any temperature above that causes ice to melt. The heat is used to break down the molecular structure of ice.
Ice will not go beyond zero degree Celcius as any heat above that is used to break it down to liquid.
The water formed by the ice is unable to gain in temperature as it is also losing heat to the ice, so the liquid around the ice remains at zero degree Celcius UNTIL the ice has FULLY melted.
It's a very common MCQ in SA1. It's also in your practice papers.
In fact, no solid can go beyond its own melting point.
I hope this helps.
Aiyo Mr Wan , you making it sound so complicated again (:
thank you! it really helped!=)
...Michelle...=)
Cassilda, which part?
Mr. Wan
U said water evaporate at any temperature but what if u place the water at Tunda when the temperature is-50 ºC .Will it still evaporates? (When it is still in the liquid state)
jin jie
*Tundra
jinjie
Mr. Wan, I hope you can answer this question. For the test and the practice paper, the question asks about 'What is the relationship...' I don't understand the question o.o" If you don't answer never mind, because it's for the test ;p ( And others )
Jinjie, tundra has extremely low temperature only at night.
In all cases, there will still be evaporation as there will be water vapour in the air given out by organisms. Water still evaporates as long as it has not frozen in the tundra. It's just that there is very little water evaporated.
Tundra questions will not be asked.
Lydia, "relationship" questions are gift questions. The answers are usually "The higher the...., the more the ...." or "The higher the ....., the lesser the ....."
An example: Relationship between evaporation and temperature.
The higher the temperature, the higher the rate of evaporation.
Does it help?
Just in case some of you were wondering about the tundra answer.
Water vapour does not evaporate. Water vapour is evaporated water.
When organisms breathe, water has already evaporated from them in the form of water vapour.
Remember, evaporation is the change of state from liquid (water) to gas (water vapour).
When you see the word "water vapour", it means water has already evaporated.
Sorry if it sounded confusing. It'd be confusing not to type in details.
Ths Mr. Wan
jinjie
Thanks Mr. Wan ;D
woot!! that REALLY HELPED Mr. Wan! that time I also was confused with the puestion on the relationship thingy but scared you say dun bother to answer! thanks! that time I wan thinking of leaving it blank....XP hahahs no lah.. good questions Lydia!
...Michelle...=) hope you had fun fer the holidays Lydia!
i need to ask: is hot wATer vapour steam?
Hot water vapour can be water vapour in a very hot environment like desert.
Steam can be called "hot water vapour" as well or sometimes "very hot water vapour".
Usually, when we see "hot water vapour", we treat it as "steam" or something very close to steam.
umm... a question based on practice paper 2b:
330
(b) What properties of air are shown in the above experiment?
I am not quite sure of the thing about properties... What does it mean?
thank you!
...Michelle...=)
I am sorry... it is supposed to be 33) not 330... paisehXP
...Michelle...=)
Air is matter.
So it has mass and it occupies space.
It has no definite volume.
It has no definite shape.
These are the 4 properties of air.
thank you!
If we want to say a container is wider than the other container... ow do we phrase it?
Sorry... it is how other than ow...XP
umm... I am not soo sure of how to do (37) b) about how water is collected at the bottom of the trough after three days.... I am not soo sure of what the question mean by trough... ok... can teach me?=)
trough = container
This question is the one I've discussed with the class in the Science Textbook.
It was a PSLE question hehe
Clue: Water flow towards the direction of the stone....
thanks alot!!! but my sis told me it is about pressure, condensation and evaporation... I know how to do liao... thank you fer guiding me all these questions!=)
ths Mr Wan 4 the ans !
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