properties of water Flashcards
what happens in a cells water?
all metabolic reactions
what percentage of the mass of a cell is water?
70-95%
what is water useful for on earth and what percentage of it is covered in water?
it is a major habitat for organisms
71%
what is the chemical makeup of water?
H2O
what is the bond within a water molecule?
covalent bond between 2 hydrogen atoms with 1 oxygen.
what charge does a water molecule have?
neutral. none.
the sharing of electrons between oxygen and hydrogen is uneven. what does this mean?
the oxygen atom attracts the electrons more strongly than the hydrogen resulting in a weak negatively charged region on the oxygen and a positively charged region on the hydrogen.
what is a dipole?
a separation of charge due to uneven electron sharing
how can we class a molecule as polar?
when it has one negatively charged end and one positively charged end.
water has one positively charged end and one negatively charged end. what does this mean?
it is a polar molecule.
what does water being polar mean for hydrogen bonds?
hydrogen bond form between the positive region on one molecule and the negative region of another.
are hydrogen bonds weak or strong on their own?
weak.
are hydrogen bonds weak or strong when there are multiple present?
strong.
what are the 7 properties of water?
- good solvent
- transport medium
-high specific heat capacity
-high latent heat of vaporisation
-act as a habitat
-high surface tension and cohesion - acts as a reagent
how is water a solvent?
because it is a polar molecule, many ions and covalently bonded polar substances will dissolve in it.
what are the advantages of water being a solvent?
-allows chemical reactions to occur within cells as dissolved solutes are more chemically reactive when they are free to move about.
- metabolites can be transported efficiently (except non polar molecules)
how does water being a solvent help prokaryotes?
because it allows them to exchange substances with their surroundings via diffusion
what is specific heat capacity?
the amount of thermal energy needed to raise the temperature of 1kg of a substance by 1 degree C
what is the specific heat capacity of water
4200j/kg’c ( a lot of energy needed)
why is the specific heat capacity of water so high?
the hydrogen bonds which create water need a lot of energy to break as well as build back up.
what are the advantages of water having a high heat capacity?
- provides a stable habitat for aquatic animals.
- maintains a constant temperature because it can absorb a lot of heat without temperature fluctuations
- helps bodies maintain constant temperature because it transfers heat by travelling in the blood
what is latent heat of vaporisation?
the amount of heat added or removed from a substance to produce a change in state ( liquid to gas)
how does water change from liquid to gas?
it must absorb a large amount of thermal energy to break the hydrogen bonds so it can evaporate.
why is latent heat of vaporisation an advantage to organisms?
because only a little amount of water is required to evaporate for the organism to lose a large amount of heat.
- provides a cooling effect. eg; transpiration or sweating
