Why did the flower
change its colour?
First spray
Second spray
FIVE HYPOTHESES
2-A
1-C
WHITE OUTSIDE,
PINK INSIDE
White outer layer
1.
PINK = CLEAN
WHITE = DIRTY
1.
WHITE
OUTSIDE
PINK
INSIDE
White outer layer
2.
3-B
WHITE
DIRTY
PINK
CLEAN
PINK
CLEAN
WHITE
DIRTY
2.
4-E
PINK DYE
WHITE DYE
THE COULOUR CHANGES
INDEPENDENTLY OF THE
SPRAY
1.
2’ 37’’
PINK
2.
WHITE
WHITE
2’ 37’’
PINK
FIVE HYPOTHESES
2-A
1-C
5-D
White outer layer
WHITE OUTSIDE,
PINK INSIDE
1.
PINK = CLEAN
WHITE = DIRTY
1.
WHITE
PINK
OUTSIDE
INSIDE
WHITE ORIGINAL
White outer layer
2.
TRANSPARENT
SUBSTANCE
ON THE
2.
PETALS
WHITE
DIRTY
PINK
CLEAN
PINK
CLEAN
WHITE
DIRTY
1.
change
3-B
SUBSTANCE IN THE
SPRAY
PINK DYE
WHITE DYE
2.
4-E
Substance on the
petals put by the
teacher
THE COULOUR
CHANGES
PINK
INDEPENDENTLY OF THE
SPRAY
change
1.
PINK
2.
ANOTHER SUBSTANCE
IN THE OTHER SPRAY
Substance on the
petals put by the
teacher
WHITE
ORIGINAL
WHITE
WHITE
2’ 37’’
2’ 37’’
PINK
• Substance in the first spray:
ALKALI
(bleach)
• Substance in the second spray:
ACID
(vinegar)
• Transparent substance on the petals:
• Transparent substance on the petals:
PHENOLPHTHALEIN
Phenolphthalein is an
INDICATOR
INDICATORS are substances
that have different colours
with acids and with alkalis.
phenolphthalein
acid
alkali
There are lots of indicators:
ACID
• PHENOLPHTHALEIN
• LITMUS
• METHYL ORANGE
• BROMOTHYMOL BLUE
ALKALI
What happened then?
• On the petals of the flower, the teacher had previously put
phenolphthalein, which is an INDICATOR.
Phenolphthalein,
an indicator.
What happened then?
• In the first spray there was an ALKALI (bleach).
Phenolphthalein turns pink with alkalis, that’s why
the flower turned pink.
Alkali
(bleach)
Phenolphthalein turned pink.
The flower turned pink.
What happened then?
• In the second spray there was an ACID (vinegar).
Phenolphthalein turns transparent with acids, that’s
why the flower turned back to its original colour.
Acid
(vinegar)
Phenolphthalein turned transparent.
The flower turned back to its
original colour.