Grade 9 Chemistry, Lesson 3 - Physical and Chemical Properties and Changes - Free Educational videos for Students in K-12

Grade 9 Chemistry, Lesson 3 - Physical and Chemical Properties and Changes - By Lumos Learning

Transcript


00:00	All right . Welcome to Mr Lee Han teaches you
00:02	stuff . This is grade nine chemistry . Less than
00:04	three physical and chemical properties and changes . So physical
00:10	properties described the characteristics of substances that we can measure
00:14	. I'm just gonna go through several examples of physical
00:17	properties now , so you get an idea of what
00:19	they are , and they require a little bit more
00:22	explanation . I'll give a quick definition of what they
00:24	are . So the state of matter at room temperature
00:27	is a physical property . So whether something is a
00:30	solid or liquid or a gas , other physical properties
00:34	include the boiling and melting points , the color ,
00:38	the shyness or the luster and the density of an
00:42	object . These are all physical properties . Another one
00:45	is hardness and hardness . Is the resistance of a
00:48	solid to being scratched or dented ? Um , this
00:51	is a picture here of my canoe . It's got
00:53	a bunch of scratches on the bottom , and that's
00:55	because my canoe was not as hard as the rocks
00:58	that I ran into . So what hardness is ?
01:01	Malleability describes how easily a substance can be hammered or
01:05	bent into different shapes . So here we have a
01:08	picture of a piece of very hot metal being hammered
01:11	out . Most metals are fairly malleable . Other things
01:15	that would be malleable would be Plato . You can
01:18	very easily hammer Plato into different shapes . Ducted City
01:22	that might be another one you're not too familiar with
01:24	. This is how easily a substance can be pulled
01:26	out into wires without snapping . So if we have
01:29	a little tube of aluminum or something here we pull
01:33	on either end . That'll get stretched out without snapping
01:38	into a longer , thinner version of itself . That's
01:40	activity . Solid ability is the ability of a substance
01:46	to dissolved in a solvent . So , for instance
01:49	, salt is dissolving in water here , so the
01:52	salt is soluble in the water . That's a physical
01:55	property . Viscosity of a substance describes how quickly it
01:59	flows in its liquid form . So here we have
02:02	a picture of some honey being poured onto a plate
02:05	, and you can see that the honey is sort
02:06	of folding over on itself , and that's because it's
02:09	very viscous . So it flows very slowly . All
02:13	right , now , we're gonna look at chemical properties
02:16	, So chemical properties described the ability of a substance
02:18	to chemically react with another substance to produce a new
02:21	chemical . So for chemical properties , it's not something
02:25	where you can measure it without reacting it with something
02:30	. To see a chemical property , you have to
02:32	see a chemical reaction takes place so chemical properties can
02:37	only be seen . When a chemical reaction happens ,
02:40	You can't just look at something and say , Wow
02:42	, that looks basic . That looks acidic . There's
02:46	gonna have to be some sort of chemical reaction for
02:48	you to tell . So some examples of chemical properties
02:54	If a substance is combustible or flammable , that means
02:57	it will react quickly with oxygen and produce heat and
02:59	light . It'll catch on fire if a substance is
03:04	acidic or basic . That also describes how it reacts
03:08	with other chemicals . So that's a chemical property .
03:12	Okay , so now we're gonna look at chemical and
03:13	physical changes . So not properties , but changes when
03:18	a new chemical substances created . It is a chemical
03:21	change . So , for example , if we have
03:24	to hydrogen react with one oxygen to make H 20
03:28	or water , that's going to be a chemical change
03:31	because a new substance , a new chemical substance ,
03:34	the water has been created . If , on the
03:38	other hand , a chemical is not changed . The
03:41	chemicals schools don't change is nothing new . It's a
03:43	physical change . So if we have liquid water turning
03:47	into solid water or ice , this is a physical
03:50	change . Things did change a change state , but
03:55	the chemicals are all the same , so it's not
03:57	a chemical change . So here are several clues that
04:02	a new chemical has been created . A new color
04:06	appears . Heat or light are given off . Bubbles
04:11	of gas are formed . A solid material called a
04:15	precipitate appears when two liquids are mixed and the change
04:20	is difficult to reverse . So if you see any
04:23	or all of those , it's usually a good clue
04:26	that a chemical reaction has taken place . A chemical
04:30	change has taken place . Alright , so now we're
04:33	going to go through several different scenarios and decide whether
04:36	they are physical or chemical changes . So , first
04:39	off , baking a loaf of bread is this physical
04:41	or chemical . This one's chemical . It's very hard
04:45	to reverse . You can't revert the bread back into
04:48	dough . Uh , and also there's also a color
04:53	change , right ? It's a darker brown when it's
04:56	baked . What about cutting a slice of bread ?
05:01	This one is physical so although it's hard to reverse
05:05	, you can't unsee lice . The bread , uh
05:08	, the chemicals that you end up with at the
05:10	end are the same chemicals that you started with ,
05:12	right ? Nothing new has been created . We've just
05:15	changed the shape of the bread . Putting peanut butter
05:19	on bread . Well , this one . The color
05:22	changes , I guess , because there's peanut butter on
05:24	it . But you're still starting off with bread and
05:29	peanut butter , and you end up with bread and
05:30	peanut butter , so there's really no change here .
05:33	There's no new molecules being created , so this one
05:37	is a physical change . What about setting the bread
05:41	on fire ? So we're producing light and heat .
05:46	There will be a color change in the bread .
05:48	It's getting blackened . This is a chemical change .
05:53	You will not be able to unfair this bread mixing
05:58	red and yellow paint to get orange . So here
06:01	we definitely have a color change . And that was
06:03	one of our one of our clues that a chemical
06:06	change has happened . But in this case , this
06:09	is a physical change . So we're really just mixing
06:12	all the little particles of paint together to make an
06:15	orange color . But the molecules that make up the
06:19	paint have not really changed . They're all still the
06:22	same paint molecules , if you will , all right
06:27	, turning on a light bulb . This one's a
06:30	little tricky as well , because it produces light and
06:32	heat , which is another one of our clues that
06:35	a chemical change has taken place . But this is
06:38	very easy to reverse . You just turn the light
06:41	switch back off and it goes off . So this
06:45	is not a chemical change . This is just a
06:47	physical change and frying an egg . This is our
06:51	last example . Frying an egg . It definitely changes
06:54	color . It's very difficult to reverse , basically .
06:57	Well , you can't reverse it . You can't on
06:58	fried egg . Basically , any time you cook anything
07:03	or you bake anything , you are making a chemical
07:07	change . So frying an egg is a chemical change
07:10	. So that's it for this video . Tune in
07:13	for the next video . The History of Atomic Theory

Summarizer

DESCRIPTION:

OVERVIEW:

Grade 9 Chemistry, Lesson 3 - Physical and Chemical Properties and Changes is a free educational video by Lumos Learning.

This page not only allows students and teachers view Grade 9 Chemistry, Lesson 3 - Physical and Chemical Properties and Changes videos but also find engaging Sample Questions, Apps, Pins, Worksheets, Books related to the following topics.