Chapter 2.4.1 (Exam 1) Properties of Water Flashcards
The Properties of Water Are Critical to the Chemistry of Life
What do water’s unusual properties result from?
Polarity
Ability to form hydrogen bonds
What are the unique features and special properties of H2O?
Ice floats
Melting, freezing and heat capacity
Cohesion and surface tension
Why does ice float?
Each molecule is hydrogen-bonded to four other molecules in a rigid, crystalline structure
More space between molecules makes ice less dense than water
Why is it important that ice floats?
It allows aquatic ecosystems to thrive under the ice in colder temperatures
What is specific heat?
amount of energy needed to raise temperature of 1 gram of a substance by 1 degree C
Why does water have a high specific heat?
Many hydrogen bonds:
Ice requires a lot of energy to melt, to break the hydrogen bonds
When water freezes, a lot of energy is released to the environment
What is the biological relevance of water’s high specific heat?
Resistant to temperature changes – maintenance of constant temperatures
Water has a high heat of vaporization. What does this mean?
A lot of heat energy is required to change water from the liquid to gaseous state (evaporation)
Why does water have a high heat of vaporization? How does this explain why we sweat to cool down?
Many hydrogen bonds
Water absorbs heat from your body to evaporate
What is cohesion of water?
Hydrogen bonds between water molecules cause them to stick together:
Helps water move through plants
Results in surface tension
What is adhesion of water?
Attraction of water molecules to other molecules of a different type
Where do most chemical reactions of life take place?
In aqueous/water-based solutions
What is a solution?
substance (solute) dissolved in a liquid (solvent)
How does dissolving molecules affect their properties?
Dissolved molecules
don’t lose their identity
and properties;
they can still react
What is a solution?
The answer to a problem nerd
