Biochem Water Flashcards
Polarity of water molecules:
They are amphipathic and polar- slight positive charge on hydrogens and slight negative on oxygen.
How does the polarity of water affect it’s intermolecular forces.
The slight positive charge of the hydrogen atom causes it to form hydrogen bonds with the slightly negative oxygen of a different water molecule.
How strong are hydrogen bonds?
Hydrogen bonds are individually weak but collectively make water very stable.
How does the polarity of water effect it as a solvent?
Water is polar and therefore can only dissociate ions and polar molecules.
How do solutes dissolve in water.
Hydrogen bonds form with negative ions ; these force counteract the ionic bond between the two ions. The negative oxygen atom attracts the positive ion. The water molecules then surround two ions and become hydrated.
Polar substances that dissolve in water are known as…
Hydrophilic (like water)
When do substances not dissolve in water?
When the substance is non-polar or its intramolecular forces are stronger than hydrogen bonding.
What is colloid suspension
Where intramolecular forces of molecules are stronger than the force of the hydrogen bonds; however the molecule is still polar. This causes a layer of water to form around the molecule, dispersing individual molecules but not breaking them down/ dissociating them.
Why is Water’s properties as a solvent important?
All substance essential for functional living organisms (glucose, amino acids, fats, vitamins, respiratory gases) transport around the body. Furthermore many metabolic reactions take place in solution.
Summary of how the polarity of water is useful.
The charged nature of water allows it to be an effective solvent and makes it very stable.
The thermal properties of water are cause by what?
The hydrogen bonds between molecules.
What are the thermal properties of water?
High specific heat capacity
High latent heat
Ice is less dense than water.
Why are the thermal properties of water important inside organisms?
The high specific heat capacity means that the body remains at an almost constant temperature and requires a large loss/gain to change; this is essential for ensuring homeostasis to maintain metabolic reactions and the ideal enzyme activity.
Why is ice less dense than water?
As the water molecules cool down they lose kinetic energy and can therefore form more hydrogen bonds, to form these bonds the molecules spread out more and so this cause water to expand when freezing and also become less dense.
Why is sweating an efficient cooling mechanism?
When water molecules evaporate they require a large amount of energy and-so absorb the thermal energy of the organism.
