What is chemical equilibrium? - George Zaidan and Charles Morton

941,091 views ใƒป 2013-07-23

TED-Ed


ืื ื ืœื—ืฅ ืคืขืžื™ื™ื ืขืœ ื”ื›ืชื•ื‘ื™ื•ืช ื‘ืื ื’ืœื™ืช ืœืžื˜ื” ื›ื“ื™ ืœื”ืคืขื™ืœ ืืช ื”ืกืจื˜ื•ืŸ.

ืชืจื’ื•ื: Ido Dekkers ืขืจื™ื›ื”: Zeeva Livshitz
00:08
Say two people are walking down the street,
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ื ื’ื™ื“ ืฉืฉื ื™ ืื ืฉื™ื ื”ื•ืœื›ื™ื ื‘ืจื—ื•ื‘,
00:10
and they bump into each other.
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ื•ื”ื ืžืชื ื’ืฉื™ื ืื—ื“ ื‘ืฉื ื™.
00:11
They'll just shake it off and walk on.
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ื”ื ืคืฉื•ื˜ ื™ื–ื•ื–ื• ื•ื™ืžืฉื™ื›ื• ืœืœื›ืช.
00:14
Sometimes that happens with molecules too.
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ืœืคืขืžื™ื ื–ื” ืงื•ืจื” ื’ื ืขื ืžื•ืœืงื•ืœื•ืช.
00:16
They just bounce off each other, and that's that.
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ื”ืŸ ืจืง ืžืชื ื’ืฉื•ืช ืื—ืช ื‘ืฉื ื™ื”, ื•ื–ื”ื•.
00:19
But what if two people were to bump into each other,
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ืื‘ืœ ืžื” ืื ืฉื ื™ ืื ืฉื™ื ื™ืชื ื’ืฉื• ืื—ื“ ื‘ืฉื ื™,
00:21
and during that collision,
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ื•ื‘ืžื”ืœืš ื”ื”ืชื ื’ืฉื•ืช ื”ื–ื•
00:22
one person's arm got severed
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ื™ื“ ืฉืœ ืื“ื ืื—ื“ ืชืงื˜ืข
00:24
and reattached to the other person's face?
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ื•ืชืชื—ื‘ืจ ืœืคืจืฆื•ืฃ ืฉืœ ื”ืื“ื ื”ืฉื ื™?
00:27
Now that sounds really weird,
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ืขื›ืฉื™ื• ื–ื” ื ืฉืžืข ืžืžืฉ ืžื•ื–ืจ,
00:29
but it's similar to one of the many ways
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ืื‘ืœ ื–ื” ื“ื•ืžื” ืœืื—ืช ืžื”ืจื‘ื” ื“ืจื›ื™ื
00:31
that molecules can react with each other.
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ืฉืžื•ืœืงื•ืœื•ืช ื™ื›ื•ืœื•ืช ืœื”ื’ื™ื‘ ืื—ืช ืขื ื”ืฉื ื™ื”.
00:34
Two molecules can join and become one.
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ืฉืชื™ ืžื•ืœืงื•ืœื•ืช ื™ื›ื•ืœื•ืช ืœื”ืชื—ื‘ืจ ื•ืœื”ืคื•ืš ืœืื—ืช.
00:36
One can split apart and become two.
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ืื—ืช ื™ื›ื•ืœื” ืœื”ืชืคืฆืœ ื•ืœื”ืคื•ืš ืœืฉืชื™ื™ื.
00:39
Molecules can switch parts.
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ืžื•ืœืงื•ืœื•ืœืช ื™ื›ื•ืœื•ืช ืœื”ื—ืœื™ืฃ ื—ืœืงื™ื.
00:41
All these changes are chemical reactions,
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ื›ืœ ื”ืฉื™ื ื•ื™ื™ื ื”ืืœื” ื”ื ืชื’ื•ื‘ื•ืช ื›ื™ืžื™ื™ื•ืช,
00:43
and we can see them happening around us.
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ื•ืื ื—ื ื• ื™ื›ื•ืœื™ื ืœืจืื•ืช ืื•ืชืŸ ืงื•ืจื•ืช ืกื‘ื™ื‘ื ื•.
00:45
For example, when fireworks explode,
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ืœื“ื•ื’ืžื”, ื›ืฉื–ื™ืงื•ืง ืžืชืคื•ืฆืฅ,
00:48
or iron rusts,
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ืื• ื‘ืจื–ืœ ืžื—ืœื™ื“,
00:49
or milk goes bad,
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ืื• ื—ืœื‘ ืžืชืงืœืงืœ,
00:50
or people are born,
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ืื• ืื ืฉื™ื ื ื•ืœื“ื™ื,
00:51
grow old,
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ืžื–ื“ืงื ื™ื,
00:52
die,
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00:52
and then decompose.
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ืžืชื™ื,
ื•ืื– ื ืจืงื‘ื™ื.
00:54
But chemical reactions don't just happen willy nilly!
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ืื‘ืœ ืชื’ื•ื‘ื•ืช ื›ื™ืžื™ื•ืช ืœื ืคืฉื•ื˜ ืกืชื ืงื•ืจื•ืช!
00:57
Everything has to be right.
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ื”ื›ืœ ื—ื™ื™ื‘ ืœื”ืชืื™ื.
00:59
First, the molecules have to hit each other
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ืจืืฉื™ืช, ื”ืžื•ืœืงื•ืœื•ืช ื—ื™ื™ื‘ื•ืช ืœืคื’ื•ืข ืื—ืช ื‘ืฉื ื™ื”
01:01
in the right orientation.
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ื‘ื–ื•ื™ืช ื”ื ื›ื•ื ื”.
01:03
And second, they have to hit each other hard enough,
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ื•ืฉื ื™ืช, ื”ืŸ ื—ื™ื™ื‘ื•ืช ืœืคื’ื•ืข ืื—ืช ื‘ืฉื ื™ื” ื—ื–ืง ืžืกืคื™ืง,
01:05
in other words, with enough energy.
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ื‘ืžื™ืœื™ื ืื—ืจื•ืช, ืขื ืžืกืคื™ืง ืื ืจื’ื™ื”.
01:08
Now you're probably thinking
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ืขื›ืฉื™ื• ืืชื ื‘ื˜ื— ื—ื•ืฉื‘ื™ื
01:09
that a reaction just happens in one direction and that's it.
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ืฉืชื’ื•ื‘ื” ืคืฉื•ื˜ ืงื•ืจื” ื‘ื›ื™ื•ื•ืŸ ืื—ื“ ื•ื–ื”ื•.
01:12
Sometimes that's true.
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ืœืคืขืžื™ื ื–ื” ื ื›ื•ืŸ.
01:13
For example, things can't unburn
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ืœื“ื•ื’ืžื”, ื“ื‘ืจื™ื ืœื ื™ื›ื•ืœื™ื ืœื—ื–ื•ืจ ืžืฉืจื™ืคื”
01:15
or unexplode.
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ืื• ืžืคื™ืฆื•ืฅ.
01:17
But most reactions can happen in both directions,
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ืื‘ืœ ืจื•ื‘ ื”ืชื’ื•ื‘ื•ืช ื™ื›ื•ืœื•ืช ืœืงืจื•ืช ืœืฉื ื™ ื”ื›ื™ื•ื•ื ื™ื,
01:20
forward and reverse.
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ืงื“ื™ืžื” ื•ืื—ื•ืจื”.
01:23
There's no reason that our face-arm guy
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ืื™ืŸ ืฉื•ื ืกื™ื‘ื” ืฉื‘ื—ื•ืจ ืขื ื”ื–ืจื•ืข ื‘ืคืจืฆื•ืฃ
01:25
can't bump into armless girl,
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ืœื ื™ื•ื›ืœ ืœื”ืชืงืœ ื‘ื‘ื—ื•ืจื” ืœืœื ื™ื“,
01:27
reattaching that arm back to its original socket.
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ื•ืชืžืฉื•ืš ืืช ื”ื™ื“ ืœืžืงื•ืžื” ื”ืžืงื•ืจื™.
01:30
Now let's zoom out a bit.
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ืขื›ืฉื™ื• ื‘ื•ืื• ื ืขืฉื” ืงืฆืช ื–ื•ื.
01:31
Now let's say that you've got
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ืขื›ืฉื™ื• ื‘ื•ืื• ื ื’ื™ื“ ืฉื™ืฉ ืœื›ื
01:32
a thousand people on the street,
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ืืœืฃ ืื ืฉื™ื ื‘ืจื—ื•ื‘,
01:34
and all of them start with their limbs
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ื•ื›ื•ืœื ื™ืชื—ื™ืœื• ืขื ื”ืื‘ืจื™ื ืฉืœื”ื
01:35
normally attached.
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ืžื—ื•ื‘ืจื™ื ื›ืจื’ื™ืœ.
01:37
At the beginning, every collision is a chance
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ื‘ื”ืชื—ืœื”, ื›ืœ ื”ืชื ื’ืฉื•ืช ื”ื™ื ืกื™ื›ื•ื™
01:39
for Person A to transfer an arm to Person B's face.
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ืœืื“ื ื. ืœื”ืขื‘ื™ืจ ื–ืจื•ืข ืœืคืจืฆื•ืฃ ืฉืœ ืื“ื ื‘.
01:43
And so at the beginning,
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ื•ื›ืš ื‘ื”ืชื—ืœื”,
01:44
more and more people end up
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ื™ื•ืชืจ ื•ื™ื•ืชืจ ืื ืฉื™ื ื™ื”ื™ื•
01:45
with arms attached to their faces or arms missing.
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ืขื ื–ืจื•ืขื•ืช ืžื—ื•ื‘ืจื•ืช ืœืคื ื™ื ืื• ื–ืจื•ืขื•ืช ื—ืกืจื•ืช.
01:48
But as the number of people with arm-faces
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ืื‘ืœ ื›ืฉืžืกืคืจ ื”ืื ืฉื™ื ืขื ื–ืจื•ืขื•ืช ืขืœ ื”ืคื ื™ื
01:51
and missing arms grows,
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ื•ื™ื“ื™ื™ื ื—ืกืจื•ืช ื’ื“ืœ,
01:53
collisions between those people become more likely.
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ื”ืชื ื’ืฉื•ื™ื•ืช ื‘ื™ืŸ ื”ืื ืฉื™ื ื”ืืœื” ื™ื•ืชืจ ืกื‘ื™ืจื•ืช.
01:56
And when they bump into each other,
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ื•ื›ืฉื”ื ืžืชื ื’ืฉื™ื ืื—ื“ ื‘ืฉื ื™,
01:58
guess what?
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ื ื—ืฉื• ืžื”?
01:59
Normal-appendage people are reproduced.
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ืื ืฉื™ื ืขื ื–ืจื•ืขื•ืช ื ื•ืจืžืœื™ื•ืช ืžืชืจื‘ื™ื.
02:02
Now the number of limb transfers per second forward
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ืขื›ืฉื™ื• ืžืกืคืจ ื”ืขื‘ืจื•ืช ื”ืื‘ืจื™ื ืœืฉื ื™ื” ืงื“ื™ืžื”
02:05
will start high and then fall,
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ื™ืชื—ื™ืœ ื’ื‘ื•ื” ื•ื™ืคื•ืœ,
02:07
and the number of limb transfers per second backward
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ื•ืžืกืคืจ ื”ืขื‘ืจื•ืช ื”ืื‘ืจื™ื ืื—ื•ืจื” ืœืฉื ื™ื”
02:10
will start at zero and then rise.
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ื™ืชื—ื™ืœ ื‘ืืคืก ื•ื™ื’ื“ืœ.
02:12
Eventually they'll meet,
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ื‘ืกื•ืคื• ืฉืœ ื“ื‘ืจ ื”ื ื™ืคื’ืฉื•,
02:13
they'll be the same.
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ื”ื ื™ื”ื™ื• ืื•ืชื• ื”ื“ื‘ืจ.
02:14
And when that happens,
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ื•ื›ืฉื–ื” ืงื•ืจื”,
02:15
the number of people in each state stops changing,
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ืžืกืคืจ ื”ืื ืฉื™ื ื‘ื›ืœ ืžืฆื‘ ืžืคืกื™ืง ืœื”ืฉืชื ื•ืช,
02:19
even though people are still bumping into each other
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ืœืžืจื•ืช ืฉืื ืฉื™ื ืขื“ื™ื™ืŸ ื ืชืงืœื™ื ืื—ื“ ื‘ืฉื ื™
02:21
and exchanging limbs.
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ื•ืžื—ืœื™ืคื™ื ืื‘ืจื™ื.
02:23
Now how many people do you think
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ืขื›ืฉื™ื• ื›ืžื” ืื ืฉื™ื ืืชื ื—ื•ืฉื‘ื™ื
02:25
there are in each state?
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ืฉื ืžืฆืื™ื ื‘ืžืฆื‘ ื”ื–ื”?
02:26
Half and half, right?
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ื—ืฆื™ ื•ื—ืฆื™, ื ื›ื•ืŸ?
02:27
No, well, maybe.
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ืœื, ื‘ืขืฆื, ืื•ืœื™.
02:29
It depends.
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ื–ื” ืชืœื•ื™.
02:30
It could be 50/50,
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ื–ื” ื™ื›ื•ืœ ืœื”ื™ื•ืช 50/50,
02:32
but it could be 60/40
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ืื‘ืœ ื’ื 60/40
02:33
or 15/85,
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ืื• 15/85,
02:34
or anything.
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ืื• ื›ืœ ื“ื‘ืจ.
02:35
We chemists have to get our little, gloved hands dirty
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ืื ื—ื ื• ื”ื›ื™ืžืื™ื ืฆืจื™ื›ื™ื ืœืœื›ืœืš ืืช ื™ื“ื™ื ื• ื”ืงื˜ื ื•ืช, ืขื˜ื•ื™ื•ืช ื”ื›ืคืคื•ืช
02:38
- ah, well, we're in a lab so not really dirty -
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- ืื”, ื•ื‘ื›ืŸ, ืื ื—ื ื• ื‘ืžืขื‘ื“ื” ืื– ืœื ื›ืœ ื›ืš ืžืœื•ื›ืœื›ื•ืช -
02:41
to figure out what the actual distribution
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ื›ื“ื™ ืœื’ืœื•ืช ืžื” ื”ื™ื—ืก ื”ืืžื™ืชื™
02:43
of molecules is.
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ืฉืœ ื”ืžื•ืœืงื•ืœื•ืช.
02:44
Even though each of limb transfers
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ืœืžืจื•ืช ืฉื›ืœ ื”ืขื‘ืจืช ืื™ื‘ืจ
02:46
is a pretty dramatic event for the people involved,
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ื”ื™ื ื“ื™ ื“ืจืžื˜ื™ืช ืœืื ืฉื™ื ื”ืžืขื•ืจื‘ื™ื,
02:49
if we zoom out,
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ืื ื ืขืฉื” ื–ื•ื ื”ื—ื•ืฆื”,
02:50
we see population numbers that don't change.
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ืื ื—ื ื• ื ืจืื” ืžืกืคืจื™ ืื•ื›ืœื•ืกื™ื” ืฉืœื ืžืฉืชื ื™ื.
02:53
We call this nirvana equilibrium,
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ืื ื—ื ื• ืงื•ืจืื™ื ืœื ื™ืจื•ื•ื ื” ื”ื–ื• ืฉื™ื•ื•ื™ ืžืฉืงืœ ,
02:55
and it doesn't just happen with chemical reactions.
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ื•ื–ื” ืœื ืงื•ืจื” ืจืง ืขื ืชื’ื•ื‘ื•ืช ื›ื™ืžื™ื•ืช.
02:58
Things like gene pools
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ื“ื‘ืจื™ื ื›ืžื• ืžืขื’ืœ ื’ื ื™ื
02:59
and highway traffic show the same pattern.
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ื•ืชื ื•ืขื” ื‘ื›ื‘ื™ืฉ ืžื”ื™ืจ ืžืจืื™ื ืืช ืื•ืชื” ื”ืชื‘ื ื™ืช.
03:02
It looks pretty still from 30,000 feet,
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ื–ื” ื ืจืื” ื“ื™ ื“ื•ืžื ืž 10,000 ืžื˜ืจ,
03:04
but there is lots of crazy stuff
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ืื‘ืœ ื™ืฉ ื”ืจื‘ื” ื“ื‘ืจื™ื ืžื˜ื•ืจืคื™ื
03:06
happening on the ground,
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ืฉืงื•ืจื™ื ืขืœ ื”ืงืจืงืข,
03:07
you just need to zoom in to see it.
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ืืชื ืจืง ืฆืจื™ื›ื™ื ืœืขืฉื•ืช ื–ื•ื ืคื ื™ืžื” ื›ื“ื™ ืœืจืื•ืช ืืช ื–ื”.
ืขืœ ืืชืจ ื–ื”

ืืชืจ ื–ื” ื™ืฆื™ื’ ื‘ืคื ื™ื›ื ืกืจื˜ื•ื ื™ YouTube ื”ืžื•ืขื™ืœื™ื ืœืœื™ืžื•ื“ ืื ื’ืœื™ืช. ืชื•ื›ืœื• ืœืจืื•ืช ืฉื™ืขื•ืจื™ ืื ื’ืœื™ืช ื”ืžื•ืขื‘ืจื™ื ืขืœ ื™ื“ื™ ืžื•ืจื™ื ืžื”ืฉื•ืจื” ื”ืจืืฉื•ื ื” ืžืจื—ื‘ื™ ื”ืขื•ืœื. ืœื—ืฅ ืคืขืžื™ื™ื ืขืœ ื”ื›ืชื•ื‘ื™ื•ืช ื‘ืื ื’ืœื™ืช ื”ืžื•ืฆื’ื•ืช ื‘ื›ืœ ื“ืฃ ื•ื™ื“ืื• ื›ื“ื™ ืœื”ืคืขื™ืœ ืืช ื”ืกืจื˜ื•ืŸ ืžืฉื. ื”ื›ืชื•ื‘ื™ื•ืช ื’ื•ืœืœื•ืช ื‘ืกื ื›ืจื•ืŸ ืขื ื”ืคืขืœืช ื”ื•ื•ื™ื“ืื•. ืื ื™ืฉ ืœืš ื”ืขืจื•ืช ืื• ื‘ืงืฉื•ืช, ืื ื ืฆื•ืจ ืื™ืชื ื• ืงืฉืจ ื‘ืืžืฆืขื•ืช ื˜ื•ืคืก ื™ืฆื™ืจืช ืงืฉืจ ื–ื”.

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