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WATER
- CHEMISTRY OF
WATER
- Each water molecule
is slightly polarised,
- This means that there is an
ever so slightly negative part,
the oxygen atom, and an ever
so slightly positive part, the
hydrogen atoms
- The separation of
this charge is called
a dipole. The
charges are
represented as δ+
or δ-
- The separation of
this charge is called
a dipole. The
charges are
represented as δ+
or δ-
- The most important
result of this charge
separation is that water
molecules will form
hydrogen bonds.
- This is caused by a weak
electrostatic attraction
between the negative
oxygen atom of one
molecule and the positive
hydrogen atoms of another
molecule
- This means the molecules
of water stick together more
than you would expect as
although hydrogen bonds
are weak, there are a great
amount of them.
- Due to this water has high
melting and boiling points,
as it takes more energy to
break the attractive force of
all the hydrogen bonds.
- This also explains waters
relatively high points in
comparison to molecules
of a similar size. Water
has a high specific heat
capacity.
- This also explains waters
relatively high points in
comparison to molecules
of a similar size. Water
has a high specific heat
capacity.
- Due to this water has high
melting and boiling points,
as it takes more energy to
break the attractive force of
all the hydrogen bonds.
- This is caused by a weak
electrostatic attraction
between the negative
oxygen atom of one
molecule and the positive
hydrogen atoms of another
molecule
- This means that there is an
ever so slightly negative part,
the oxygen atom, and an ever
so slightly positive part, the
hydrogen atoms
- Each water molecule
is slightly polarised,
- IMPORTANCE
OF WATER
- Water is an unusual
and excellent solvent
- Many substances will dissolve
in it. Water has a dipole, so
ionic substances which are
made of positive and negative
ions will dissolve in it.
- For example salts like sodium
chloride will dissolve as the positive
and negative ions separate and
become surrounded by water
molecules.
- Polar substances (compounds
with covalent bonds, but with small
charges) will not dissolve in most
solvents, like ethanol, except for
water.
- Water can also carry many
non-polar molecules. They would
form colloids where the solute
particles are larger than the solvent
particles
- Some substances don't dissolve in
water and instead form emulsions
(oil and water) or suspensions
where liquid and solid mix when
constantly stirred.
- Some substances don't dissolve in
water and instead form emulsions
(oil and water) or suspensions
where liquid and solid mix when
constantly stirred.
- Water can also carry many
non-polar molecules. They would
form colloids where the solute
particles are larger than the solvent
particles
- For example salts like sodium
chloride will dissolve as the positive
and negative ions separate and
become surrounded by water
molecules.
- As chemical reactions in
cells occur in water the
ability to act as a solvent is
vitally important
- Many substances will dissolve
in it. Water has a dipole, so
ionic substances which are
made of positive and negative
ions will dissolve in it.
- Water has one of the highest
known surface tensions
- Surface tension is high in
water due to the hydrogen
bonds 'pulling' down on the
molecules.
- Because there is no attraction
between water and air a thin
layer of surface tension is
created. This is vital to plants
and life in water masses.
- Because there is no attraction
between water and air a thin
layer of surface tension is
created. This is vital to plants
and life in water masses.
- Surface tension is high in
water due to the hydrogen
bonds 'pulling' down on the
molecules.
- The water molecule is
amphoteric
- This means that it can act
as either an acid or a base.
(H+ Ions as a proton donor,
OH- ions as a proton
accepter)
- This means that water is
an ideal medium for
biochemical reactions
within cells. Also acting as
a buffer to prevent
reactions from changing
PH.
- This means that water is
an ideal medium for
biochemical reactions
within cells. Also acting as
a buffer to prevent
reactions from changing
PH.
- This means that it can act
as either an acid or a base.
(H+ Ions as a proton donor,
OH- ions as a proton
accepter)
- Water is an unusual
and excellent solvent
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