Chemistry deals with the study of matter, it
is one of the pure main branches of physical sciences that deals with the
comprehensive studies of the structure, nature and composition of matter in
relation to our environment. Here’s a demonstration common in chemistry classes
by MrGrodski Chemistry. Two chemicals, hydrochloric acid and ammonia, are
placed next to each other. They don’t touch. But one suddenly starts smoking.
What happened?
is one of the pure main branches of physical sciences that deals with the
comprehensive studies of the structure, nature and composition of matter in
relation to our environment. Here’s a demonstration common in chemistry classes
by MrGrodski Chemistry. Two chemicals, hydrochloric acid and ammonia, are
placed next to each other. They don’t touch. But one suddenly starts smoking.
What happened?
This is the famous “white
smoke” demonstration. It’s a simple thing, but it’s interesting to look
at, and it demonstrates a very good chemical principle. Unfortunately, it
involves a vial full of hydrochloric acid, which isn’t an easy thing to handle,
so it’s mostly demonstrated in chemistry classrooms. Put a stoppered beaker of
hydrochloric acid next to a stoppered beaker of ammonia. Nothing happens. Yank
out the stoppers, and suddenly, the beaker of acid will start giving off plumes
of white smoke.
smoke” demonstration. It’s a simple thing, but it’s interesting to look
at, and it demonstrates a very good chemical principle. Unfortunately, it
involves a vial full of hydrochloric acid, which isn’t an easy thing to handle,
so it’s mostly demonstrated in chemistry classrooms. Put a stoppered beaker of
hydrochloric acid next to a stoppered beaker of ammonia. Nothing happens. Yank
out the stoppers, and suddenly, the beaker of acid will start giving off plumes
of white smoke.
It doesn’t take too much thinking to
guess that fumes from the ammonia have traveled through the air and reacted to
the hydrochloric acid, but given the two materials are out in the open, why
does no smoke form over the ammonia bottle?
guess that fumes from the ammonia have traveled through the air and reacted to
the hydrochloric acid, but given the two materials are out in the open, why
does no smoke form over the ammonia bottle?
The smoke isn’t really the result of
combustion. It’s a fine salt powder that forms in the air when the ammonia and
the acid combine. Here’s the equation the describes the process:
combustion. It’s a fine salt powder that forms in the air when the ammonia and
the acid combine. Here’s the equation the describes the process:
NH3 + HCl —> NH4Cl
A look at the chemical equation
gives us the reason that only the hydrochloric acid starts “smoking.”
The ammonia is one nitrogen atom and three hydrogen atoms. Since hydrogen is
such a lightweight, ammonia has a molecular mass of a mere seventeen grams per
mole. The hydrochloric acid is the heavyweight. Chlorine is about thirty-five
and a half grams per mole, and the hydrogen brings the acid up to thirty-six
grams per mole.
gives us the reason that only the hydrochloric acid starts “smoking.”
The ammonia is one nitrogen atom and three hydrogen atoms. Since hydrogen is
such a lightweight, ammonia has a molecular mass of a mere seventeen grams per
mole. The hydrochloric acid is the heavyweight. Chlorine is about thirty-five
and a half grams per mole, and the hydrogen brings the acid up to thirty-six
grams per mole.
We all know that a pot of liquid
left on a counter will evaporate eventually. Its molecules will turn to gas and
diffuse through the air. Studies show the diffusion rate of a substance is
inversely proportional to the square root of the molecular mass. In other words
– the heavier the molecular mass, the slower the gas will diffuse through a
given space. Hydrochloric acid, then, is a lumbering gas. Ammonia is quick.
Anyone who has dealt with it knows that an unstoppered bottle of ammonia smells
up a room. The hydrochloric acid beaker appears to be smoking because the ammonia
gets to it before it can even clear the rim of its own beaker.
left on a counter will evaporate eventually. Its molecules will turn to gas and
diffuse through the air. Studies show the diffusion rate of a substance is
inversely proportional to the square root of the molecular mass. In other words
– the heavier the molecular mass, the slower the gas will diffuse through a
given space. Hydrochloric acid, then, is a lumbering gas. Ammonia is quick.
Anyone who has dealt with it knows that an unstoppered bottle of ammonia smells
up a room. The hydrochloric acid beaker appears to be smoking because the ammonia
gets to it before it can even clear the rim of its own beaker.
[Sources: MrGrodski Chemistry, Chem Demos.]
Watch video by clicking here
