TALK ABOUT ALCOHOL
SCIENCE/
ENVIRONMENTAL
STUDIES
WORKSHEET 5
INVESTIGATING THE DEHYDRATING EFFECTS OF
ALCOHOL (14–16s)
About 60% of the mass of the adult human body is water. Our cells need plenty of water
so the essential chemical reactions taking place inside them can work properly. In spite
of how much water someone takes in each day, the water content of the body usually
remains very stable. This is because hormones act on the kidneys and blood system to
keep the balance right.
The most important of these is ADH, or anti-diuretic hormone. It is secreted by the
pituitary gland and acts on the kidneys to reabsorb water. This means that body water is
conserved and the amount leaving the body in urine is controlled.
Alcohol inhibits the secretion of ADH so the kidneys produce more urine and the body
loses too much water. This is why alcohol has a dehydrating effect on the human body,
and leads to the symptoms of a 'hangover' (e.g. feeling tired, thirsty and headachey).
The dehydrating properties of alcohol (ethanol) can be used to preserve biological
specimens. The alcohol kills off decay-causing microbes by dehydrating them, so the
specimens do not 'go off'.
1
www.talkaboutalcohol.co.uk
TALK ABOUT ALCOHOL
SCIENCE/
ENVIRONMENTAL
STUDIES
WORKSHEET 5
ACTIVITY
ONE
In this experiment, you will investigate the dehydrating effect of alcohol (ethanol) on
living cells.
Safety note
An adult should supervise this experiment because ethanol catches fire easily. There
must be no fires or naked flames in the room, and you shouldn’t eat or drink while you
are doing this experiment.
Apparatus
4 250ml beaker
4 100ml each of 10%, 20%, 30%, 40% ethanol
4 large raw fresh potato
4 white tile
4 forceps or fork
4 sharp knife
4 cling film
4 paper towel
4 ruler
Method
Follow the steps shown in the diagrams and record your results in a table similar to the
one given.
2
www.talkaboutalcohol.co.uk
TALK ABOUT ALCOHOL
SCIENCE/
ENVIRONMENTAL
STUDIES
WORKSHEET 5
ACTIVITY
ONE
Investigating the dehydrating effects of alcohol (14–16s)
Follow these steps four times, using a different % concentration of ethanol each time.
1.
Assemble your apparatus.
2.
Cut three potato chips of equal size.
Potato cut
into thick slices
Potato cut
Potato
cutthick slices
into
into thick slices
3.
Potato
slice
Potato
Potato
slice
slice
Potato cut
Knife
into thick slices
Tile
Knife
Knife Potato cut
Tile into thick slices
Tile
Potato
Cut 3 equal
slice
size chips
Cut 3 equal
Potato
Cut 3 size
equal
chips
slice
size chips
Knife
Tile
Cut 3 equal
size chips
Knife a ruler and
Measure each chip with
Tile
record your results.
4.
3 equal
Put the ethanol andCut
chips
into the
size chips
beaker.
Chip
Chip
Ruler
Chip
Ruler
Ruler
Ethanol
Chip
3Ethanol
Chips
Ethanol
3 Chips
3 Chips
Ruler
Ethanol
Ruler
Chip
Cling film
5. Ensure the chips are fully
submerged,
Cling
filmwith
and cover the beaker
tightly
Cling film
SAFETY!
cling film.
ALCOHOL FUMES
6.
3 Chips
Ethanol
remove
After 24 hours,
the chips
3
Chips
from the alcohol and the beaker.
SAFETY!
CAN
CATCH FIRE
SAFETY!
ClingALCOHOL
film
FUMES
ALCOHOL
CAN FUMES
CATCH FIRE
CAN CATCH FIRE
Cling film
SAFETY!
ALCOHOL FUMES
CAN CATCH FIRE
SAFETY!
ALCOHOL FUMES
Paper
towel
CAN CATCH
FIRE
Paper towel
Paper towel
Chip
Paper towel
Paper towel
Chip
Chip
Chip
3
Ruler
Chip
Ruler
Ruler
www.talkaboutalcohol.co.uk
Ruler
Chip
Ethanol
Ruler
3 Chips
Ethanol
TALK ABOUT ALCOHOL
3 Chips
Cling film
SAFETY!
SCIENCE/
ENVIRONMENTAL
STUDIES
WORKSHEET 5
Cling film
ALCOHOL FUMES
ACTIVITY
ONE
CAN CATCH FIRE
SAFETY!
ALCOHOL FUMES
CAN CATCH FIRE
7. Place the chips onto a paper towel.
8. Measure each chip again and record
your results.
Paper towel
Paper towel
Chip
Ruler
Chip
Chip
Ruler
Chip
Results
Record your results for each percentage of ethanol in a table similar to the one below..
Percentage
(%) ethanol
concentration
Start of
End of
experiment
experiment
Length of each
potato chip
(mm) =
Average length
of potato chips
(mm) (add
length of each
of the 3 chips
and divide by
3 to get the
average) =
Length of each
potato chip
(mm) =
End result
Average length
of potato chips
(mm) =
Change in
average length
of potato chips
(mm) =
Conclusion
1. How does alcohol affect living cells?
2. How does the effect differ with different concentrations of alcohol?
3. Why is alcohol used to preserve biological specimens?
4. Why can drinking alcohol make someone feel thirsty afterwards?
4
www.talkaboutalcohol.co.uk