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Physical Vs. Chemical Changes - Explained

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hey you guys this is mr. Millington

today we're gonna talk about physical

versus chemical changes so what are

physical changes well it says right here

that physical changes are changes in a

substance that do not involve a change

in the identity or a chemical makeup of

that substance so let's take a look at a

few examples here down below let's

suppose we have some peanuts and what

we're gonna do is we're gonna grind

these peanuts down to make peanut butter

we still have peanuts here and we still

have peanuts here it's just taken on a

different physical form so this is going

to be a physical change this would be

example of a physical change right here

grinding peanuts into peanut butter

let's take a look at this piece of paper

right here if we fold this piece of

paper up to make a paper airplane this

would be an example of a physical change

we're not changing the chemical makeup

of the paper

we're simply changing its physical

appearance over here if we take a look

at this copper bar right here what we're

gonna end up doing is we're gonna end up

turning this into copper wire and

anytime you can take a metal and turn it

into wire that that that shows that that

that metal is ductile okay ductile is

the process or ductility is the process

of turning a metal into wire so we still

have copper here and it's still copper

here it's just taken on a different

physical form let's take a look right

here we have ice which we know is h2o

that's water in the solid stage or state

and what we're gonna do with this ice is

we're gonna melt it down into liquid

water so it's still h2o here we did not

change the chemical makeup of this we

just changed the physical appearance so

this two would be a physical change all

right so once again changes in a

substance that do not involve a change

in the identity or a chemical makeup of

that substance are physical changes and

it's important to keep in mind and this

is very important that all changes in

state of matter are gonna be physical

changes so anytime you go from solid to

liquid or liquid to gas or gas to liquid

and liquid back to solid it's going to

be a physical change just like the ice

melting over here that is going to be a

physical change all right

lastly it says all physical changes are

not necessarily accompanied by a

chemical change and

talk about chemical changes in a second

but understand that when we when we take

these peanuts and make peanut butter out

of it we're not changing the chemical

composition okay this is only going to

be a physical change same right here

same thing right here and same thing

right here okay so now let's take a look

at chemical changes okay it says right

here that chemical changes our changes

in a substance that do involve a change

in the identity or chemical makeup of

that substance so if we take a look here

if we have some sugar here and we end up

making some type of alcohol over here

that process is called fermentation

fermentation is the process of turning

sugar into alcohol so we have sugar over

here which is one type of compound and

we have alcohol over here which is a

totally different substance and so that

is going to be a chemical change another

example right here if we have an iron

nail and we leave it out on the grass

overnight it might turn into this rusty

nail over time right that process is

called oxidation right the iron nail

here the iron is combining with oxygen

to produce some iron oxide or rust over

here that is going to be a chemical

change in the chemical composition of

this nail now is different than when

then what we started with if we take a

look right here we have some logs here

and if we light these logs on fire like

we see right here this will be an

example of a chemical change right this

is gonna be a chemical change any time

we burn something or anytime there's

some sort of combustion going on that's

going to be a chemical change we're

changing the chemical composition of

these of these logs if we take a look

right here if we take some water which

is made up of two hydrogen's bonded to

one oxygen and we pass an electric

current through it what ends up

happening is the hydrogen and the

hydrogen's break free from the oxygens

and end up producing hydrogen gas and

oxygen gas okay so we have one substance

over here which is water and we have two

brand new substances over here which is

hydrogen gas and oxygen gas and this too

would be an example of a chemical change

okay so one last thing that you need to

keep in mind and this is very

important as well it says right here

that all chemical changes are

accompanied by physical changes so

primarily all of these are gonna be

examples of chemical changes but there's

a physical change also you take a look

there's a physical change in the

appearance here there's a physical

change in the appearance of these logs

there's a physical change in the

appearance of the iron nail there's a

physical change in the appearance of

this water so all chemical changes are

accompanied by a physical change but the

opposite is not true not all physical

changes are accompanied by chemical

changes okay so here are some examples

of physical and chemical changes let's

now take a look at a few more and see if

you can determine which is which okay so

let's just quickly go through each one

of these examples here and what we need

to do is determine if it is a physical

or chemical change and once again we

will assume that all chemical changes

are also physical changes so right here

if we have condensing water vapor so

that's water vapor that is turning back

to a liquid that is a change in state of

matter that will always be a physical

change let's look at this next one the

combustion of gasoline okay so when gas

gasoline catches on fire what's

happening is that there's a chemical

change going on that gasoline is being

converted into something else or

something totally different so this will

be an example of a chemical change let's

look at this next one turning water into

hydrogen and oxygen gas we just talked

about electrolysis and anytime you're

turning one thing or one chemical into

two different chemicals or one substance

into two different substances that's

going to be a chemical change as well

let's look at this one milk showering so

over time what happens is that milk is

breaking down and it's being converted

into different substances so that's

going to be a chemical change let's look

at this one the sublimation of dry ice

so sublimation that's the process of

going from a solid directly to a gas

without passing the liquid stage first

and in a different video we talked about

that so that's going to be a change in

state of matter and that's going to be a

physical change

remember all changes in

states of matter are always physical

changes what about turning copper into

wire turning copper into wire it's still

going to be copper it just has a

different physical form so that is a

physical change as well let's look at

this one the fermentation of sugar into

alcohol we talked about this a few

moments ago we are turning sugar into

something totally different we're

turning one chemical substance into a

different chemical substance so that

will be a chemical change and last but

not least we have evaporating water

evaporating tells you that that liquid

is turning into a gas in this case water

vapor so that is going to be a change in

state of matter and all changes in state

of matter are physical changes okay so

that's physical and chemical changes in

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