Solvent Properties
What type of molecule is water that makes it an excellent solvent?
A polar molecule
What kind of heat capacity does water have?
A high heat capacity
Does ice float or sink in water?
Ice floats
What is cohesion?
Attraction between like molecules
What is adhesion?
Attraction between unlike molecules
What are substances called that dissolve in water?
Hydrophilic (“water loving”)
How does water’s temperature change in response to heat gain or loss?
It changes very slowly
Why does ice float?
Because water expands when it freezes and becomes less dense
What kind of bonds cause water’s strong cohesion?
Hydrogen bonds
What causes water to adhere to other molecules?
Hydrogen bonds between water and other polar covalent molecules
Why are ionic substances soluble in water?
Because the charged poles of water molecules interact with the ions
Why does it take a lot of energy to heat or cool water?
Because of hydrogen bonding between water molecules
What causes water to expand when it freezes?
Hydrogen bonds forming rigid crystals that keep molecules apart
What does water’s strong cohesion produce at the surface?
High surface tension
What’s an example of adhesion in action?
Capillary action or water sticking to paper
Why don’t nonpolar covalent molecules dissolve in water?
They lack charged poles (they are hydrophobic)
How does water’s high heat capacity benefit large bodies of water?
It keeps their temperatures stable despite air temperature changes
How is ice different from most other substances when it freezes?
Most substances contract and become denser; water expands
Why can some insects walk on water?
Because of water’s high surface tension caused by cohesion
What property allows water to move up narrow tubes?
Capillary action
What term describes molecules that do not dissolve in water?
Hydrophobic (“water fearing”)
How does sweating help regulate body temperature?
When sweat evaporates, it takes heat with it, cooling the body
How does ice floating help marine life?
It forms an insulating layer that protects life beneath it
Does cohesion involve similar or different types of molecules?
Similar (like) molecules
How are cohesion and adhesion similar?
Both are caused by hydrogen bonds