DO GASES HAVE DENSITY

1
LESSON 4

• DO GASES HAVE DENSITY?

2
OBJECTIVES

• FIND OUT WHETHER AIR HAS VOLUME
• DESIGN AN EXPERIMENT THAT CAN BE USED TO FIND OUT
  THE MASS OF A SAMPLE OF AIR
• TRY TO MEASURE THE MASS OF A SAMPLE OF AIR

3
MATERIALS

• 1 THICK-WALLED PLASTIC BOTTLE
• 1 VACUUM PUMP WITH RUBBER VALVE/STOPPER
• 1 RUBBER WASHER
• 1 100 Ml GRADUATED CYLINDER
• BALANCE

4
GETTING STARTED

• OBSERVE 2 TEST TUBES
• FUNNEL GOES INTO THE TEST TUBE BUT IS HELD FIRMLY
  IN PLACE BY A RUBBER STOPPER
• 2ND TEST TUBE WITH A FUNNEL BUT IS NOT SEALED
  AROUND THE EDGE OF THE TUBE

5
IN YOUR NOTEBOOK...

• DESCRIBE WHAT HAPPENS WHEN COLORED WATER IS
  POURED INTO EACH FUNNEL.
• WHY DOES WATER BEHAVE DIFFERENTLY IN EACH FUNNEL?

6
IN YOUR NOTEBOOK...

• LOOK AT THE SECOND PIECE OF APPARATUS MADE OF 2
  SYRINGES CONNECTED BY A TUBE.
• DESCRIBE WHAT YOU OBSERVE WHEN ONE SYRINGE IS
  PUSHED IN. DRAW A PICTURE OF WHAT HAPPENS.

7
INQUIRY 4.1

• FINDING THE DENSITY OF AIR

8
INQUIRY 4.1

• WHAT WILL YOU NEED TO MEASURE IN ORDER TO
  CALCULATE THE DENSITY OF AIR?
• GRADUATED CYLINDER
• BALANCE

9
DISCUSS WITH YOUR GROUP

• DETERMINE A PROCEDURE FOR HOW YOU WOULD DETERMINE
  THE DENSITY OF THE AIR IN THE BOTTLE. WRITE DOWN
  YOUR PROCEDURE ON A PIECE OF NOTEBOOK PAPER.
  WELL SHARE OUR IDEAS IN 5 MINUTES.

10
RECORD THIS PROCEDURE ON YOUR STUDENT SHEET 4.1

• VOLUME TO FIND THE VOLUME OF THE PLASTIC JAR,
  MEASURE AND POUR WATER FROM THE GRADUATED
  CYLINDER INTO THE JAR UNTIL IT IS FULL. THIS WILL
  GIVE YOU AN EQUIVALENT AMOUNT OF AIR.

11

• MASS TO FIND THE MASS OF THE AIR IN THE JAR,
  USE THE BALANCE TO GET THE MASS WITH THE AIR
  INSIDE AND THEN USE A VACUUM PUMP TO REMOVE THE
  AIR AND USE THE BALANCE AGAIN TO GET THE MASS.
  SUBTRACT THE TWO MASS NUMBERS.

12

• FIND THE MASS AND VOLUME OF AN AIR SAMPLE. UNDER
  STEPS 2 AND 3 ON THE STUDENT SHEET RECORD YOUR
  RESULTS AND USE THEM TO CALCULATE THE DENSITY OF
  AIR.
• MASS OF AIR- .6 g
• VOLUME OF AIR 600 mL
• DENSITY - .001 g/mL

13
REFLECTIONS 4.1

• HOW DOES THE DENSITY OF AIR COMPARE WITH THE
  DENSITY OF SOLIDS AND LIQUIDS?
• The density of air is extremely less than that of
  solids and liquids.

14

• 2. ARE THE RESULTS ALL THE SAME?
• PRETTY CLOSE
• 3. DO YOU THINK THE PROCEDURE YOU USED IS VERY
  PRECISE?
• Yes, we took precise measurements

15
ANSWER THE FOLLOWING ON YOUR STUDENT SHEET

• WHY DO THE CLASS RESULTS VARY SO MUCH?
• VARIANCES COULD BE FROM DIFFERENCES IN THE
  PLASTIC BOTTLES, AMT. OF AIR PULLED OUT.
• WHY DO SOME THINGS FLOAT IN AIR?
• THEY ARE LESS DENSE THAN AIR.