Water and Transport Flashcards
What type of molecule is water and what does it mean ?
A polar molecule
- Meaning it has a positive and negative end or
- The oxygen is ( delta/slightly) negatively charged due to unpaired electrons and the hydrogen’s are (delta/slightly) positively charged as their electrons are closer to the oxygen.
What is the first property of water ?
It is an excellent solvent:
- water is a good solvent because it can form hydrogen bonds with other polar molecules or charged ionic compounds.
- This is handy for humans, since our blood consists mostly of water which is able to dissolve hydrophilic molecules such as glucose, ions and some amino acids.
What does hydrophilic mean ?
- Water loving
- Hydrophilic molecules are polar and ionic
- Hydrophilic molecules get absorbed
What does hydrophobic mean ?
- Water resistant
- hydrophobic molecules are non-polar
- hydrophobic molecules only dissolve in oil-based substances
What is the second property of water ?
It has a high latent heat of evaporation- this means that a lot of energy is used to convert water from a liquid to a gas.
This is because alot of energy is required to break multiple hydrogen bonds within water.
Other than water, list 3 other examples of where hydrogen bonds are found in biological molecules.
- Protein secondary structure
- Between chains of cellulose
- Between strands of bases in DNA
What is hydrolysis
when a molecule of water is involved in the
breaking of a bond in another molecule.
Explain how the properties of water make it an ideal transport medium.
- Water is a an excellent solvent.
- As ionic compounds can easily dissolve in water.
- This is because water molecules surround the ions to allow them to separate from their neighbouring molecules to dissolve
- Water also has many hydrogen bonds which gives very good adhesive and cohesive properties .
- water is liquid so has the ability to flow.
What is cohesion
- When water molecules stick to each other because of their hydrogen bonds.
- Cohesion makes it possible to pull against gravity (e.g xylem - straw)
- Cohesion is responsible for surface tension when water meets air e.g pond skaters.
p.s always talk about hydrogen bonds and always talk about cohesion when it come to transportation
Why will ionic compounds dissolve in water ?
- ionic compounds are made fro positive and negative ions
- Water is made up of a delta positive and delta negative charges
- the charges of water molecules disrupt forces holding compounds together
/ attracts individual ions
What is the 3rd property of water
It has a high specific heat capacity
- all those hydrogen bonds within water are great at absorbing energy, which means you have to add a lot of it to heat water up.
- This is really useful for marine life since it means that bodies of water are fairly resistant to changes in temperature, making it a stable habitat in which to live.
Why is water a good solvent.
description of water as a {polar / dipole / dipolar} molecule
(1)
- water surrounds (polar) molecules allowing them to dissolve(1)
- Forming hydrogen bonds
