Bio 3 B
Lab#2 -­‐ Water
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Lab#2: Properties of water
WATER LAB
Important Word Roots
Water
• Old English w æterian "moisten”
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www.personal.psu.edu
Polar • Latin polus "an end of an axis
+/-­‐
Hydrogen Bonding • Hydro = w ater • Joined
• *gen = a combining form meaning “that which produces”
When in doubt –
Say Hydrogen Bonding!
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Bio 3 B
Lab#2 -­‐ Water
Polar, Non Polar and Amphipathic • Polar • Non-­‐Polar • Amphipathic
• Combining Form • Experience www.york.ac.uk
www.marin.edu
Important Word Roots
Adhesion Cohesion Capillary Action • French adhésion = • French cohésion • Capillaris "of hair”
= sticking sticking t o • Action = Move
together
Add to another Water sticking to substance
water
http://water.usgs.gov/edu/adhesion.html
springtolife.weebly.com
Important Word Roots
Hydro
• Water
*Phylic
• Loving
*Phobic
• Fearing
A charge is what makes something hydrophilic
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Bio 3 B
Lab#2 -­‐ Water
WATER AND LIFE
– Life on Earth began in w ater and evolved t here for 3 billion years.
• Modern life remains tied to water.
• Your cells are composed of 70%–95% water.
– The abundance of w ater is a major reason Earth is habitable.
Figure 2 .9
Water’s Life-­‐S upporting Properties
• The polarity (charge) of water molecules and the hydrogen bonding that results explain most of water’s life-­‐supporting properties.
1. Water molecules s tick together.
2. Water h as a s trong resistance to change in temperature.
3. Frozen water floats.
4. Water is a common s olvent for life.
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Water’s Life-­‐S upporting Properties
– The polarity ( charge) of water molecules and the hydrogen b onding that results explain most of water’s life-­‐supporting p roperties.
• Water molecules stick together.
– Cohesion • Water has a strong resistance to change in temperature.
• Frozen water floats.
• Water is a common solvent for life.
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Bio 3 B
Lab#2 -­‐ Water
– Surface tension is the measure of h ow d ifficult it is to stretch or b reak the s urface of a liquid.
• Hydrogen bonds give water an unusually high surface tension.
Water’s Life-­‐S upporting Properties
– The polarity ( charge) of water molecules and the hydrogen b onding that results explain most of water’s life-­‐supporting p roperties.
• Water molecules stick together.
• Water has a strong resistance to change in temperature.
– Hydrogen bonds • Frozen water floats.
• Water is a common solvent for life.
Water’s Life-­‐S upporting Properties
– The polarity ( charge) of water molecules and the hydrogen b onding that results explain most of water’s life-­‐supporting p roperties.
• Water molecules stick together.
• Water has a strong resistance to change in temperature.
• Frozen water floats.
• Water is a common solvent for life.
Proff. Zannie Dallara 4
Bio 3 B
Lab#2 -­‐ Water
The Biological Significance of Ice Floating
– When water molecules get cold enough, they move apart, forming ice.
Cold = Less Energy = Less movement = More O rganized = More space = floats •
•
If ice did not float, ponds, lakes, and even t he oceans would freeze solid.
Life in w ater could not survive if bodies of water froze solid.
Water’s Life-­‐S upporting Properties
– The polarity ( charge) of water molecules and the hydrogen b onding that results explain most of water’s life-­‐supporting p roperties.
• Water molecules stick together.
• Water has a strong resistance to change in temperature.
• Frozen water floats.
• Water is a common solvent for life.
Water as the Solvent of Life
– A solution is a liquid consisting of a homogeneous (looks the same throughout) mixture of two or more substances.
• The dissolving agent is the solvent.
• The dissolved substance is the solute.
– When water is t he solvent, t he result is an aqueous solution.
Salt crystal
Sodium ion in solution
Na
+
Na
+
–
Cl
Cl–
Chloride ion in solution
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Bio 3 B
Lab#2 -­‐ Water
Figure 2.14
Hydrogen bond
Liquid water
Hydrogen bonds
constantly break
and re-­form.
Ice
Stable hydrogen bonds
hold molecules apart,
making ice less dense
than water.
Water as the Solvent of Life
– A solution is a liquid consisting of a homogeneous
mixture of two or more substances.
• The dissolving agent is the solvent.
• The dissolved substance is the solute.
– When water is the solvent, the result is an aqueous
solution.
© 2 0 1 3 P earso n Ed u catio n , In c.
Other Uses of Water
Synthesis of Polymers
• Condensation Reaction (Dehydration Reaction)
• Molecule of water is released
– One molecule contributes –OH – Other molecule contributes –H
• This is repeated as the polymer elongates
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Bio 3 B
Lab#2 -­‐ Water
Other Uses of Water
Breakdown of Polymers
• Hydrolysis Reaction
• Break with addition of water
– A –H is added t o one monomer
– A –OH is added t o other monomer
nerf.wikia.com
www.memrise.com
Other Molecules Detergent -­‐
ßHydrophilic ßHydrophobic www.york.ac.uk
Other Molecules Oil
ßHydrophilic ßHydrophobic wps.prenhall.com
www.emec.com.eg
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Bio 3 B
Lab#2 -­‐ Water
Capillary Action • Skinny tube • Touch tube to drop of water on desk
• Shake out the water
• Do that a couple times • Record observations • Answer questions Water ’s Life Supporting Properties
The S heer Awesomeness that are Hydrogen Bonds
1. Water m olecules stick together.
2. Water has a strong resistance to change
in temperature.
3. Frozen water floats.
4. Water is a common solvent for life.
Proff. Zannie Dallara 8