3.2 Water Flashcards
Why water polar and how are hydrogen bonds made here?
Electronegative difference between oxygen and hydrogen atoms mean that hydrogen atoms will be slightly positive and oxygen negative .
- hydrogen bonds from between a Lone pair connected to an electronegative atom on one molecule and a partially positive hydrogen atom connected to another electronegative atom (making it positive) of another molecule .
What are properties of water
- High latent heat of vaporisation and SHC
- More dense as liquid than solid
- cohesive and adhesive properties
- Surface tension
- Can Act as a solvent
High latent heat vaporisation + SHC why?
1) due to having to break down many hydrogen bonds it takes more energy to increase the temperature of 1kg by 1k (meaning higher SHC) and evaporate too (Latent heat vaporisation) compared to other compounds of same size
How does having high shc and vaporisation make water useful in life?
IMPORTANT
(Coolant, stable)
What does being coolant useful for
- 1) Water can act as a coolant
- here it buffers temperature changes during chemical reactions in cells, as large amount of energy is needed to raise temp, so even with energy released in chemical reactions the temp won’t increase , keeping temp constant which is necessary for enzyme action as ENZYME WONT DENATURE
- high latent heat means a lot of energy taken to evaporate, so animals will sweat and this COOLS you as it evaporated / water ESCAPING FROM PLANT IN TRANSPIRATION
- THIS MEANS ANIMALS USE LESS ENERGY ON TEMPERATURE CONTROL
2) Gives a constant environment for aquatic animals
- water temp won’t rapidly increase as a lot of energy needed to raise temp- good habitat as , giving a stable environment for aquatic animals. Also constantly stays liquid as a result , giving a habitat
Why More dense in liquid than solid?
- after water cooled below 4°, water forms a tetrahedral lattice of holes due to the 4 hydrogen bonds present in each water molecule with another .
- This holds the atoms in fixed distances which are greater than the average distance between atoms in the liquid state, thus the density is less
- ice floats
What use is low density solid ice for life?
1) Ice is less dense it floats and it freezes from top bottom, rather from bottom top, creating an INSULATING LAYER which means water underneath doesn’t freeze, allowing aquatic animals to survive.
2) Ice also forms a habitat on TOP of ice too
What gives water cohesive and adhesive properties, (how plants draw water) and what are they?
- 1)due to polarity, and hydrogen binds here water is ATTRACTED TO EACH OTHER , and moves as ONE MASS = cohesion
- thus if you suck on straw all water will move up, and same way plants can DRAW WATER UP ROOTS)
2) adhesion is attraction fo water molecules to other surfaces, such as water remaining in hand after washing .
- this also allows water to be drawn up, both cohesive and adhesive properties mean they can stick together and the surface and be drawn up together
Surface tension
Why useful for living organisms
As water are more strongly cohesive with EACH OTHER rather than air, a “skin” of surface tension is formed
2) this allows for some insects living on the surface of water like pond skaters
What makes water a good solvent for polar molecules and why useful ?!!
Ionic and polar molecules can dissolve as the charged ions will interact with negative and positive regions of water . As they can be dissolved, they can be TRANSPORTED IN ORGANISMS
- Water can act as a medium for chemical reactions too, and transport things in and out of the cell with it
- such as ions, urea out of body, phosphate ions for plants etc
What allows for water to be able to transport substances through things like blood and vascular bundle (what is capillary action)
- cohesive and adhesive means water stick together and to surfaces that are polar
- creates a CAPILLARY ACTION, WHERE WATER IS DRAWN UP A TUBE EVEN AGAINST GRAVITY
How does water allow organisms to survive in range of temperatures
1) coolant
- high vaporisation, so sweat means evaporation will cool down organisms
- THUS USE LESS ENERGY ON TEMPERTAURE CINTROL
- acts as a buffer for chemical reactions due to high Shc, a lot of energy needed to increase temp , meaning it increases slowly, keeping conditions constant for enzymes
2) thermally stable environment for animals
- ice less dense meaning float cream insulating layer so water underneath don’t freeze
- water temperature remains constant throughout due to high shc , so stays water giving stable environment instead of GAS
3) provides habitat for animals too on ice,
