JOAN CARTAN-HANSEN, HOST:

A COMPOUND IS A SUBSTANCE MADE

UP OF DIFFERENT ELEMENTS.

AN ELEMENT IS SOMETHING THAT

CAN'T BE BROKEN DOWN INTO A

SIMPLER SUBSTANCE.

WE LIST ELEMENTS ON THE PERIODIC

TABLE.

WHEN YOU COMBINE ELEMENTS, LIKE

TWO ATOM OF HYDROGEN AND ONE

ATOM OF OXYGEN, YOU CAN GET H2O

OR WATER.

BUT IF YOU COMBINE TWO ATOMS OF

HYDROGEN AND TWO ATOMS OF

OXYGEN, YOU GET HYDROGEN

PEROXIDE, SOMETHING USED TO

BLEACH THINGS AND SOMETHING YOU

DEFINITELY SHOULDN'T DRINK.

THEY'RE BOTH COMPOUNDS, BOTH

MADE UP THE SAME ELEMENTS, BUT

VERY DIFFERENT SUBSTANCES.

THE STUDY OF ELEMENTS AND

COMPOUNDS IS A BIG PART OF THE

SCIENCE OF CHEMISTRY.

CHEMISTS LEARN HOW TO COMBINE

ELEMENTS AND TO TAKE APART

COMPOUNDS.

THEY LEARN WHAT SUBSTANCES ARE

MADE OF AND HOW ELEMENTS COMBINE

TO MAKE NEW MATERIALS.

THEY ALSO LEARN ABOUT

PROPERTIES.

EVERY SUBSTANCE HAS A UNIQUE SET

OF PROPERTIES.

PHYSICAL PROPERTIES ARE

SOMETHING YOU CAN SEE OR

MEASURE.

LOOK AT THE PUPPIES.

THEY ARE ALSO SOFT AND COLORFUL

AND WEIGH A FEW POUNDS.

COLOR, TEXTURE, AND WEIGHT ARE

SOME OF THE PHYSICAL PROPERTIES

OF THE PUPPIES.

(AWE)

BUT SCIENTISTS ARE ALSO

INTERESTED IN A SUBSTANCE'S

CHEMICAL PROPERTIES.

CHEMICAL PROPERTIES ARE HOW A

SUBSTANCE ACTS UNDER CERTAIN

CONDITIONS.

YOU CAN SEE A SUBSTANCE'S

CHEMICAL PROPERTIES ONLY THROUGH

A CHEMICAL REACTION.

AND IF YOU KNOW WHAT A

SUBSTANCE'S CHEMICAL PROPERTIES

ARE, YOU CAN CLASSIFY IT,

IDENTIFY IT IN AN UNKNOWN

SOLUTION, PREDICT HOW IT WILL

BEHAVE, AND FIGURE OUT HOW TO

SEPARATE IT OUT.

THIS IS MY FRIEND CHRIS

SAUNDERS.

HE'S A CLINICAL ASSISTANT

PROFESSOR AT BOISE STATE

UNIVERSITY'S DEPARTMENT OF

CHEMISTRY AND BIOCHEMISTRY.

HE'S GOING TO SHOW US HOW YOU

CAN BREAK UP A COMPOUND INTO ITS

COMPONENTS.

CHRIS SAUNDERS, CHEMIST: WELL

OFTEN TIMES THAT'S PRETTY

DIFFICULT TO DO.

BUT ONE OF THE EASY ONES THAT WE

CAN DO IS THE ELECTROLYSIS OF

WATER.

SO WHAT I HAVE HERE IS A SET UP

WHERE I'VE TAKEN WATER AND I'M

PASSING AN ELECTRIC CURRENT

THROUGH THE WATER.

SO WHAT'S COLLECTING IN THESE

TUBES IS HYDROGEN GAS AND OXYGEN

GAS.

AND YOU'LL NOTICE THERE ARE

DIFFERENT AMOUNTS OF GAS IN THAT

TUBE BECAUSE WATER IS MADE OUT

OF TWO PARTS OF HYDROGEN TO

EVERY ONE PART OF OXYGEN.

WE CAN ALSO LOOK AT THE

DIFFERENT CHEMICAL PROPERTIES OF

HYDROGEN GAS VERSUS OXYGEN GAS.

ONE OF THEM BEING THAT HYDROGEN

GAS MAKES A NICE POP WHEN YOU

IGNITE IT.

SO WE ARE GOING TO TRY TO CATCH

THAT GAS AND TOUCH A FLAME TO IT

AND SEE WHAT HAPPENS SO LISTEN

CAREFULLY.

(POP)

SAUNDERS: NOT MUCH OF AN

EXPLOSION, BUT YOU COULD

DEFINETLY HEAR THAT THERE WAS AN

IGNITION OF THE HYDROGEN GAS.

NOW IF WE DO THAT SAME THING

WITH THE OXYGEN GAS WE ARE GOING

TO GET A DIFFERENT RESULT.

SEE NO EXPLOSION THIS TIME.

(MUSIC)

SAUNDERS: SO I HAVE SOME

SOLUTIONS HERE THAT I'VE MADE UP

AND WE ARE GOING TO MIX THEM

TOGETHER AND WE ARE GOING TO

MAKE OBSERVATIONS IN TERMS OF

HAS A CHEMICAL CHANGE HAPPENED?

I.E. HAVE WE MADE SOMETHING NEW?

IN THIS CASE WE HAVE A SOLUTION

OF POTASSIUM IODIDE AND IN THIS

SOLUTION WE HAVE LEAD NITRATE.

SO WE ARE GOING TO MIX THESE TWO

TOGETHER.

BOTH OF THEM START OFF AS CLEAR

COLORLESS LIQUIDS AND WHEN I ADD

THEM TOGETHER OBVIOUSLY

SOMETHING NEW IS BEING MADE.

IN THIS CASE THAT BRIGHT YELLOW

PRECIPITATE IS LEAD IODIDE.

NOW YOU NOTICE WHEN I MIX THESE

TWO SOLIDS TOGETHER THAT NOTHING

IS HAPPENING.

WHEN WE MIXED THEM BEFORE THEY

MADE THAT YELLOW PRECIPITATE SO

WHAT'S GOING ON?

WELL FOR THIS REACTION TO OCCUR

THEY BOTH NEED TO BE DISSOLVED

IN WATER.

SO LET'S ADD SOME WATER TO THEM

AND SEE WHAT HAPPENS.

SO RIGHT AWAY YOU CAN SEE AS WE

ADD THAT WATER THOSE COMPOUNDS

WILL DISSOLVE AND NOW THEY CAN

REACT WITH EACH OTHER SO THAT WE

MAKE THE SAME YELLOW COMPOUND

THAT WE MADE IN THE FIRST

REACTION.

(MUSIC)

SAUNDERS: SO RIGHT HERE

I HAVE A BALANCE AND WE USE A

BALANCE TO MEASURE THE MASS OF

COMPOUNDS.

AND ON THE BALANCE I HAVE A

CONTAINER OF VINEGAR AND I HAVE

A BALLOON.

INSIDE THE BALLOON I PLACED SOME

BAKING SODA AND WHEN YOU MIX

BAKING SODA AND VINEGAR TOGETHER

YOU GET A REACTION.

SO I'M GOING TO MIX THESE THINGS

TOGETHER, KEEP THEM ON THE

BALANCE AND WE'RE GOING TO SEE

WHAT HAPPENS TO THE MASS.

NOW IT'S IMPORTANT TO NOTE THAT

ONE OF THE PRODUCTS OF THIS

REACTION IS A GAS SO I NEED TO

KEEP THE BALLON ON HERE SO THAT

I CAN CATCH ALL OF THAT GAS

BECAUSE EVEN THOUGH IT'S VERY

LIGHT GAS HAS MASS AS WELL.

OH THAT'S GOING TO MAKE A MESS!

SO OUR REACTION HAS HAPPENED.

DEFINETLY THINGS HAVE CHANGED.

WE SAW A LOT OF ALL THIS

BUBBLING, WE'VE CAUGHT ALL THAT

GAS, BUT EVEN AFTER ALL OF THAT

THE MASS OF ALL THE PARTS OF OUR

REACTION HAVE NOT CHANGED.

CARTAN-HANSEN: THANKS CHRIS FOR

SHOWING US ABOUT COMPOUNDS.

CHRIS: MY PLEASURE THANKS FOR

HAVING ME JOAN.

CARTAN-HANSEN: IF YOU WANT TO

LEARN MORE ABOUT COMPOUNDS AND

LOTS OF OTHER SCIENTIFIC TOPICS,

CHECK OUT THE SCIENCE TREK WEB

SITE.

YOU'LL FIND IT AT

IDAHOPTV.ORG/SCIENCE TREK.

(MUSIC)

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