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水的作用
視頻：
水對維持正常細胞功能和血容量的重要性
水的混合物
視頻：
與水的混合物
溶液是由至少兩種物質組成的均一、穩定的混合物，被分散的物質（溶質）以分子或更小的質點分散于另一物質（溶劑）中。 水可以作為溶劑用來溶解很多種物質，用水作溶劑的溶液，即稱為水溶液。
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There
are
two
main
types
colloids
and
suspensions
有兩種主要類型:膠體和懸浮液·
Today
we're
going
to
talk
about
mixtures
今天,我們將討論混合物,
specifically
mixtures
with
water
特別是與水相關的混合物·
A
mixture
is
a
physical
not
a
chemical
combination
of
two
or
more
substances
混合物是兩種或多種物質的物理(而非化學)結合·
Each
substance
in
a
mixture
keeps
its
individual
characteristics
混合物中的每種物質保持其獨特的特性·
A
solution
also
called
a
homogeneous
mixture
溶液,也叫做均勻混合物,
consists
of
very
tiny
particles
mixed
so
uniformly
that
the
mixture
has
the
same
properties
throughout
包含非常微小的顆粒,它們均勻地混合在一起,使得整個混合物具有相同的性質·
In
contrast
a
heterogeneous
mixture
consists
of
significantly
larger
particles
that
are
not
uniformly
distributed
and
are
more
easily
seen
相比之下,異質混合物包含較大的顆粒,這些顆粒分布不均勻,更容易被看到·
The
components
of
a
heterogeneous
mixture
can
usually
be
separated
easily
異質混合物的組成成分通常可以輕松分離·
Homogeneous
water
based
mixtures
are
called
aqueous
solutions
均勻的水基混合物叫做水溶液·
The
dissolved
substance
is
called
the
solute
溶解的物質叫做溶質,
and
the
substance
that
dissolves
the
solute
in
this
case
water
is
called
the
solvent
溶解溶質的物質(在本例中是水)叫做溶劑·
Water
is
sometimes
referred
to
as
the
universal
solvent
because
it
can
dissolve
more
substances
than
any
other
liquid
水有時被稱為"萬能溶劑",因為它可以溶解比任何其他液體更多的物質·
Water
can
dissolve
many
substances
because
of
the
polar
nature
of
water
molecules
水能夠溶解許多物質,因為水分子具有極性·
This
allows
water
molecules
to
surround
and
hold
on
to
other
small
polar
molecules
這使得水分子能夠包圍并吸附其他小的極性分子·
As
a
result
the
polar
molecules
spread
out
evenly
throughout
the
water
因此,極性分子均勻地分布在水中·
Remember
water
is
the
solvent
記住,水是溶劑·
Water's
polar
nature
also
allows
the
slightly
positive
and
slightly
negative
charges
on
its
molecules
to
dissolve
ionic
compounds
known
as
salts
水的極性特性還使得水分子上的微弱正電荷和微弱負電荷能夠溶解離子化合物,稱為鹽·
Water
does
this
by
separating
the
compound
into
negatively
and
positively
charged
particles
called
ions
水通過將化合物分解成帶負電和帶正電的粒子,稱為離子,從而實現溶解·
The
negative
poles
of
water
molecules
surround
the
positive
ion
from
the
compound
水分子的負極包圍化合物中的正離子,
and
the
positive
poles
of
water
molecules
surround
the
negative
ion
from
the
compound
水分子的正極包圍化合物中的負離子·
Solutes
and
solutions
are
so
small
and
uniformly
distributed
that
solutions
are
always
transparent
溶質和溶液非常小且均勻分布,因此溶液總是透明的·
You
can
see
right
through
them
你可以透過它們看到·
Now
let's
talk
about
heterogeneous
aqueous
mixtures
現在,讓我們談談異質水溶液·
Colloids
and
suspensions
differ
primarily
in
the
size
of
their
particles
within
the
water
膠體和懸浮液的主要區別在于它們在水中粒子的大小·
In
colloids
the
particles
mixed
in
the
water
are
larger
than
the
water
molecules
在膠體中,混合在水中的顆粒大于水分子,
but
are
still
too
small
to
see
with
the
naked
eye
但仍然太小,肉眼看不見·
As
big
as
these
particles
are
they're
still
small
enough
that
the
random
motion
of
the
water
molecules
keep
them
mixed
within
the
water
這些顆粒雖然很大,但它們仍然足夠小,水分子的隨機運動使得它們保持在水中混合·
In
contrast
suspensions
contain
even
larger
particles
than
those
in
colloids
相比之下,懸浮液中含有比膠體中更大的顆粒,
but
the
particles
are
just
small
enough
to
be
suspended
in
water
when
stirred
or
shaken
但這些顆粒足夠小,可以在攪拌或搖動時懸浮在水中·
Over
time
however
the
particles
in
a
suspension
start
to
settle
to
the
bottom
of
the
container
然而,隨著時間的推移,懸浮液中的顆粒會開始沉淀到容器底部·
Heterogeneous
water
mixtures
such
as
colloids
and
suspensions
are
never
transparent
異質水混合物,如膠體和懸浮液,永遠不透明·
They're
always
cloudy
hazy
or
opaque
and
you
can't
see
through
them
它們總是渾濁的、模糊的或不透明的,無法透過它們看·
In
this
example
the
colloid
is
milk
and
the
suspension
is
sand
in
water
在這個例子中,膠體是牛奶,懸浮液是水中的沙子·
To
recap
mixtures
are
physical
rather
than
chemical
combinations
of
two
or
more
substances
總結一下,混合物是兩種或多種物質的物理而非化學結合,
and
each
substance
in
the
mixture
keeps
its
individual
characteristics
且混合物中的每種物質保持其個體特性·
A
mixture
may
be
a
solution
which
is
a
homogeneous
mixture
consisting
of
very
tiny
particles
mixed
so
uniformly
that
the
mixture
has
the
same
properties
throughout
混合物可以是溶液,它是一個均勻的混合物,包含非常微小的顆粒,它們均勻地混合在一起,使得整個混合物具有相同的性質;
or
a
mixture
may
be
heterogeneous
with
larger
particles
that
are
not
uniformly
distributed
and
are
more
easily
seen
或者混合物是異質的,包含更大的顆粒,這些顆粒分布不均勻,更容易被看到·
Aqueous
solutions
are
homogeneous
water
based
mixtures
consisting
of
tiny
ions
or
molecules
dissolved
in
water
水溶液是均勻的水基混合物,包含溶解在水中的微小離子或分子·
A
solute
is
the
dissolved
substance
in
a
solution
溶質是溶液中溶解的物質·
A
solvent
is
the
substance
that
dissolves
the
solute
溶劑是溶解溶質的物質·
Water
is
called
the
universal
solvent
because
it
dissolves
more
substances
than
any
other
liquid
水被稱為萬能溶劑,因為它能溶解比任何其他液體更多的物質·
Aqueous
colloids
and
suspensions
are
heterogeneous
mixtures
consisting
of
larger
particles
that
are
less
uniformly
distributed
and
more
easily
separated
than
the
particles
in
aqueous
solutions
水溶膠體和懸浮液是異質混合物,包含較大的顆粒,這些顆粒分布不均勻,比水溶液中的顆粒更容易分離·