35: The Properties of Water Flashcards
What are the properties of water?
- water molecules are cohesive
- water is a liquid over a wide variety of temperatures
- water has a high heat capacity
- water has a high heat of vaporization
- water is a universal solvent
- water has a high surface tension
- ice is less dense than liquid water
Describe a water molecule.
one oxygen with two hydrogen atoms (H2O)
- tend to be linked to other water molecules (through hydrogen bonds)
What makes water molecules cohesive?
go in a gang and work all together (cohesive)
- there are strong forces of attraction between molecules of water
- makes them work as if they were a single unit
What would need to be done to go from liquid to vapor?
need to break all the bonds between water molecules
Why is water a liquid in a variety of temperatures?
it has a high boiling point and low freezing point
What is freezing point?
point in which liquid water becomes ice (0 C or 32 F)
What is boiling point?
point at which liquid water becomes a gas (100 C or 212 F)
How does water have a high heat capacity?
liquid water changes temperature very slowly
- it can absorb a lot of heat without increasing its temperature
- it can also release a lot of heat without lowering its temperature
What does water’s high heat capacity explain?
it is the reason why coastal cities are going to be much warmer in winter and cooler in summer
- proximity to the ocean is going to temper the climate
Why does water have a high heat of vaporization?
takes a lot of heat to evaporate liquid water
- use a lot of heat and energy to break bonds between water molecules
- good because animals and plants can release excess heat by converting liquid water into steam or vapor through transpiration
Why is water a universal solvent?
water can dissolve a variety of compounds
- nutrients, waste pollutants
- any chemicals are soluble in water
What are the benefits of water being a universal solvent?
good for organisms who use things like blood; also good for plants to dissolve nutrients
- can make water good at conducting electricity (good or bad depending on situation)
What are the disadvantages of water being a universal solvent?
can dissolve waste; water is easily polluted
Why does water have a high surface tension?
water’s surface behaves like a membrane
- strong bonds between water molecules
- due to this, many insects and even a lizard can walk on water
What makes ice less dense than liquid water?
water expands when it freezes which is the reason why ice floats over water
- different than most other compounds, when they become solid, they contract
- lakes don’t freeze solid (but pipes break when they freeze)
What would happen if ice was not less dense than liquid water?
if we did not have this property all the lakes would freeze solid and fish would be frozen inside water
Where is the all the water on Earth?
97.6% in oceans and in saline lakes (not fresh water)
2.4% fresh water
Where is the fresh water on Earth?
87% is in ice and snow
13% liquid water
Where is the liquid fresh water on Earth?
95% is in groundwater
2% in soil moisture
3% in lakes, rivers, streams
What percent of water are in living things?
living things are made up of 70% water on average
What should we worry about?
having too much water or too little water and having poor quality water
What is an example of having too much water?
floods in Pakistan 2022 cause of Hurricane Ian
What is an example of having too little water?
drought in California 2022
What is an example of having poor quality water?
Flint Michigan 2016
