Properties of Water
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Water can absorb or lose a large amount of heat without changing temperature very quickly. What is this property of water called?
High heat capacity
What are the atoms in a molecule of water?
2 hydrogen atoms and 1 oxygen atom
What is surface tension?
The strength of water’s surface caused by attraction between water molecules that allows small objects (like insects or paper clips) to stay on top of water
Solid water is ______________ than liquid water
How are water striders able to walk on water?
Water striders are light enough so they do not break the hydrogen bonds holding the water molecules together.
What kind of molecules can water dissolve?
Polar molecules
The hydrogen end of water has what charge?
slight positive charge
Why is water able to dissolve more substances than other liquids?
It comes from its polarity: The slightly negative oxygen end is attracted to positive charges and the slightly positive hydrogen ends are attracted to negative charges
Water sticking to other surfaces/substances is known as
Adhesion
How is cohesion/adhesion beneficial to living things?
Allows small organisms to stay on top of the surface of water, allows plants to get water to the top of their leaves, etc.
Water is known as a _______________________ because it can dissolve more substances that most liquids
Universal Solvent
The oxygen end of a water molecule has what charge?
slight negative charge
Water sticking to other water molecules is known as?
Cohesion
What are the four properties of water?
1. Cohesion/adhesion
2. Water is a versatile solvent
3. Water has a high heat capacity
4. Water's expansion upon freezing
How can water's expansion upon freezing be beneficial to living things?
Ice can provide habitats for animals, regulates temp. for animals underneath the ice, etc.
Why is density NOT the reason small objects like paper clips or water striders are able to stay on top of water?
Small organisms are supported by the surface strength (attraction of water molecules to each other), not because of density differences
What kind of charges attract?
Opposites: a positive and a negative
This causes water to clump together in drops.
cohesion
What causes water's polarity?
The charges are unevenly distributed --> the molecule has two different “ends” — one slightly negative and one slightly positive
How can water's high heat capacity benefit living things?
Provides a stable temperature for organisms in bodies of water, help organisms that can't regulate their own temperature, etc.
Capillary action is made possible due to which two properties of water?
Cohesion and adhesion
What are hydrogen bonds?
Weak attractions between the slightly positive hydrogen (δ+) of one water molecule and the slightly negative oxygen (δ–) of another water molecule
Why is solid water less dense than liquid water?
When water freezes, the molecules spread out and form a more open structure. Hydrogen bonds lock water molecules into a rigid, crystal structure
Why did the paper clip float in salt water (better than regular water) but not in soapy water or alcohol water?
Salt: dissolved salt ions help water molecules stay more tightly organized at the surface
Soap: Soap molecules interfere with the attraction between water molecules
Alcohol: Alcohol molecules do not attract each other as strongly as water molecules do
How can water being a versatile solvent benefit living things?
Saliva can help to dissolve substances, digestion, blood, etc.