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What are Physical Changes?
They are changes in which only physical properties like shape , size , and state change but no new substance is formed.
- Paper folding changes shape but same paper remains.
- Balloon inflation changes size but same rubber remains.
- Chalk crushing changes form but same chalk remains.
- Original material stays chemically identical throughout the change .
Activity 5.2: Let us create and discuss
What you need:
- Few sheets of paper
- Balloon
- Small piece of chalk
- Pin
What to do:
- Step 1: Fold paper to create new objects
- Step 2: Inflate balloon and let air escape
- Step 3: Inflate another balloon and prick with pin
- Step 4: Crush chalk into powder
Do you get the same paper back when you unfold these objects?
Answer:
Yes, it is the
same paper
with
identical properties
.
- Paper material remains completely unchanged
- Only shape was temporarily different
Do you get the uninflated balloon back?
Answer:
Yes, it is the
same balloon
when
air escapes
.
- Rubber material stays exactly identical
- Size returns to original form
What happens when you prick the balloon?
Answer:
It
bursts
but
rubber pieces
are
same material
.
- Shape changes from balloon to flat pieces
- Chemical nature of rubber stays unchanged
Can you get the chalk piece back from the powder?
Answer:
No, it cannot
return
to
original shape
.
- Chalk material is still chalk
- Physical form changed permanently
Observations
What you see:
- Paper objects unfold back to flat sheets
- Deflated balloon returns to original size
- Pricked balloon becomes rubber pieces
- Chalk powder cannot reform into solid piece
Why this happens:
We have studied that
physical changes
only affect
appearance
while
keeping
the
same substance
. This is why
paper
,
rubber
, and
chalk
remain
chemically identical
despite
shape changes
.
- No new substances are formed
- Original materials keep same properties
Section Summary: A Substance May Change in Appearance but Remain the Same!
