1.1 Water Flashcards
Why is water a dipole molecule
Water contains both positive (hydrogen) and negative (oxygen) regions to its molecule
What causes the dipole in water
The greater electronegativity of the oxygen atom, draws the shared electrons in the covalent bond between the oxygen and hydrogen towards it.
Giving it a slightly negative charge. The hydrogen atom has a slightly positive charge.
What is a hydrogen bond
- Weak bonds
- between + hydrogen and - oxygen of another water molecule
what is cohesion
- water molecules show a strong attraction. = cohesion
- allows volumes of water to be drawn up the xylem vessels without breaking
what temp does water have maximum density
why is this good
- 4 degrees celsius
- Ice floats insulating water below, protecting aquatic habitats
why can insects walk on water
Surface tension due to cohesion
What is specific heat capacity?
The amount of energy needed to raise the temperature of 1kg of a substance by 1 degree.
What is the latent heat of vaporisation?
The energy needed for a substance to change from liquid to gas (evaporate)
Why is it beneficial for an animal to have a high latent heat of vaporisation?
For cooling. A large amount of body heat is required to evaporate sweat (energy is needed to break H bonds between water molecules)
What property of water allows it to act as a transport medium?
Its polarity
enables it to be a solvent for other polar molecules e.g. plasma transports glucose and ions in animals
Give examples of water as a metabolite.
Required for photosynthesis and hydrolysis reactions
Produced during respiration and condensation reactions
Why is it beneficial that water is transparent?
It allows light to pass through, enabling aquatic plants to photosynthesise
