Transcript Potato Lab

Osmosis Lab
Definition of Osmosis
WATER moves from an area of
HIGH to LOW concentration.
Problem/Purpose
• What effect will distilled water and
salt water have on the mass of a
potato slice?
• Increase in mass – water going in
• Decrease in mass – water coming out
Research
Background Knowledge
• Osmosis is the diffusion of water.
• Water moves from an area of high to low
concentration.
• The size of the substance in relationship to
the size of the openings (pores) in the
membrane will impact diffusion/osmosis.
• Cells will either remain the same, swell or
shrink as a result of osmosis.
Hypothesis
• The potato slice in the distilled water will
increase in mass.
• The potato slice in the distilled water will
decrease in mass.
• The potato slice in the salt water will increase in
mass.
• The potato slice in salt water will decrease in
mass.
DON’T FORGET YOUR REASONING . . . YOUR
“BECAUSE” STATEMENT.
Variables
• Independent
• Dependent
• What did we
change? What
experimental
condition was
under our control?
• What are we
measuring? What
data we are
collecting?
• Type of Water
• Mass of the potato
slice
The Experiment
• Control Group
• Experimental Group
• Did we have one?
• Potato in salt water
• Potato slice placed in
an isotonic solution
• No movement of
water
• Potato in distilled
water
Constants
• What did we keep the same to
control the number of variables
introduced into the experiment?
– The potato
– Volume of liquid in Petri dish
– Equipment as directed in “Materials” list
– Method used to set up the experiment
– Method used to collect data
The Data
Type of
Water
Mass Before
(grams)
Mass After
(grams)
Difference
in Mass
(grams)
% increase
or decrease
% of Change
(increase or decrease)
• Difference ÷ Mass Before × 100
• Mass Before – 4 grams
• Mass After – 6 grams
• Difference in Mass – 2 grams
• 2 g ÷ 4 g = 0.50 × 100 = 50%