Beechwood Helium Balloons
Helium
- Helium
Balloon Gas
Here
are a few facts about helium
gas
which you may find interesting.
Helium
Balloon Gas makes balloons float.
Helium is lighter than air and
just as the heaviest things will
tend to fall to the bottom, the
lightest things will rise to
the top.
If you were to fill a pop
bottle
with
helium
and
another
with
air,
the
one
filled
with
helium
would
weigh
a
gram
less
than
the
bottle
with
air.
Helium
balloons
follow
the
same
principle
as
you
do
when
you
float
in
the
water;
the
law
of
buoyancy.
If
the
water
you
displace
weighs
more
than
you
do,
you
will
float.
Helium is a colourless, odourless, tasteless inert gas at room temperature and makes up about 0.0005% of the air we breathe
What
is helium?
Helium is
a colourless,
odourless,
tasteless
inert gas
lighter than
air - at
room temperature
and makes
up about
0.0005% of
the air we
breathe
Source?
After
hydrogen, helium is the second
most abundant element in the
universe. It has been detected
spectroscopically in great abundance,
especially in the hotter stars.
It is present in the Earth's
atmosphere in about 1 part in
200,000. It is present in various
radioactive minerals as a decay
product.
Who discovered Helium?
Helium
was first detected by Janssen in 1868
during the solar eclipse as a new line
in the solar spectrum, and named by Lockyer
and Frankland. It was discovered in the
uranium mineral cleveite independently
by Ramsay and the Swedish chemists Cleve
and Langlet
Helium = Uses
Helium
is widely used as an inert gas shield
for arc welding; as a protective gas
in growing silicon and germanium crystals,
and in titanium and zirconium production.
It is also used as a cooling medium
for nuclear reactors, and as a gas
for supersonic wind tunnels. A mixture
of 80% helium and 20% oxygen is used
as an artificial atmosphere for divers
and others working under pressure.
Helium is extensively used for filling
balloons as it is a much safer gas
than hydrogen. One of the recent largest
uses for helium has been for pressurising
liquid fuel rockets
Biological
Role
Helium
has no known biological function, but it
is non-toxic.
Helium
in the Sun
Helium in the sun is generally believed to
be formed by nuclear fusion. This is where
nuclei of hydrogen, the lightest element,
combine to form helium with huge amounts
of energy released.
Liquid
helium (4He) exists in two forms, 4He I and
4He II, above and below 2.174K respectively.
The latter is unlike any other known substance.
It expands on cooling, its conductivity for
heat is enormous and neither its heat conduction
nor viscocity obeys normal rules. It remains
liquid down to absolute zero at ordinary
pressures, but can readily be solidified
by increasing the pressure
Helium
Flotation
- Helium
balloons
Helium
Balloons
work by
the law
of buoyancy.
As long
as
the helium
plus the
balloon
is lighter
than
the air
it displaces,
the balloon
will float
in the
air.
Helium is a lot
lighter
than air.
The difference
is not
as great
as
it is between
water and
air (a
litre of
water
weighs
about 1,000
grams,
while a
litre of
air weighs
about 1
gram),
but it
is significant.
Helium
weighs
0.1785
grams per
litre.
Nitrogen
weighs
1.2506
grams per
litre,
and
since nitrogen
makes up
about 80
percent
of the
air we
breathe,
1.25 grams
is a good
approximation
for the
weight
of a litre
of air.
Therefore,
if you
were to
fill a
1-litre
soda bottle
full of
helium,
the bottle
would weigh
about 1
gram less
than the
same bottle
filled
with air.
That doesn't
sound like
much --
the bottle
itself
weighs
more than
a gram,
so it won't
float.
However,
in large
volumes,
the 1-gram-per-litre
difference
between
air and
helium
can really
add up.
This explains
why blimps
and balloons
are generally
quite large
-- they
have to
displace
a lot of
air to
float.
If
you
put helium in
a balloon
and
let
go
of
the
balloon,
the
balloon
rises
until
it
pops.
When
it
pops,
the
helium
that
escapes
has
no
reason
to
stop
--
it
just
keeps
going
and
leaks
out
into
space.
Therefore,
in
the
atmosphere
there
is
very
little
helium at
any
given
time.
The helium that
is
there
comes
from
alpha
particles
emitted
by
radioactive
decay.
In
places
that
have
a lot
of
uranium
ore,
natural
gas
tends
to
contain
high
concentrations
of
helium
(up
to
7 percent).
This
makes
sense,
since
the
decay
of
uranium
emits
lots
of
alpha
particles
and
a natural
gas
pocket
tends
to
be
a sealed
container
underground. Helium is
cryogenically
distilled
out
of
natural
gas
to
produce
the
helium
we
put
in
balloons.
What causes helium balloons to lose their lift after 7 or 8 hours ?
In brief, because the helium leaks out,
they shrink, and become heavier than the
volume of air they displace. This causes
them to lose buoyancy and "sink" in
the air. The weight balance that keeps
a balloon afloat does not leave a lot of
room for leakage, so once a little leaks
out the balloon falls.
Sometimes you can catch a balloon right around the time it is neutrally buoyant, and applying heat (your hand, for instance) or cold (rub with ice cube) will change its volume just enough to make it rise or sink in the air.
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