Nitric Acid: Chemical Properties


Let’s see some reactions of nitric acid.
That is let study the chemical properties of
nitric acid. Nitric acid, undergoes decomposition when
it is hated or even in the presence of
sunlight, it decomposes to give NO2, that is, it releases
nitrogen dioxide gas, oxygen gas and water. So, on thermal
decomposition, that is when it is heated or in the presence
of sunlight, it decomposes to give nitrogen dioxide,
oxygen and forms water. We know the reaction, that a base and an acid, they react to form a salt and water. This reaction is known as neutralization
Reaction. Let’s look at some examples. So whenever this acid that is nitric
acid, it reacts with base ,we know the
metallic oxides are bases, so when nitric acid it reacts with the base potassium oxide ,it forms the
corresponding salt that this potassium nitrate and water.
Similarly this acid when it reacts with another
base, copper oxide it forms the corresponding salt
copper nitrate and forms water. Other bases, we know the metallic
hydroxides are also basis ,so when these metallic
hydroxides they react with the acid HNO3 they form the corresponding salts
and water. So when sodium hydroxide, this is a base, it reacts with an acid ,nitric acid ,it
forms the corresponding salt which is sodium nitrate and releases
water So, a base on reaction with an acid always forms the salt and water. Carbonates and bi-carbonates Whenever you see carbonates and bi-carbonates be sure
that they always react with acids to evolve carbon dioxide gas. The carbonates and bi-carbonates, they always Release carbon di-oxide gas. So when they react
with an acid that is HNO3, they form the corresponding Salt, water and they release carbon di-oxide
gas. So if you look at an example sodium
bi-carbonate it reacts with nitric acid to form the
the corresponding salt that is sodium nitrate, it releases water and it also forms carbon di-oxide
gas. So, the carbonates and bi-carbonate always release carbon dioxide gas. So we can generalize it in this form. The
carbonates and bi-carbonates on reaction with nitric
acid they form the corresponding salt, water
and release carbon dioxide gas. Similarly the sulfides and bi-sulfides. Whenever the sulfides and bi-sulfides they react with acids they release SO2 gas when we have sulfides and And bi-sulfides. So, when we have Potassium sulfide, it reacts with nitric
acid So it forms the corresponding salt. So
we get Potassium nitrate it forms water and releases sulfur dioxide gas. Similarly the bi-sulfides they also form
corresponding salt water does and release sulfur dioxide Gas. So, in this case we can say that when sulfides and bi-sulfides they react with HNO3 ,they form
the corresponding salts water and release sulfur dioxide gas. Now the action of HNO3 on non-metals. So we have HNO3 that is nitric acid, carbon is a non-metal so when carbon
reacts with HNO3 it forms carbon dioxide, H2O and releases nitrogen dioxide gas. So
whenever there is addition of oxygen that is
known as Oxidation. Since nitric acid leads to oxygen being added to carbon and nitrogen So carbon and nitrogen are getting
oxidized so HNO3 is known as an oxidizing
agent Similarly sulphur, a non-metal reacts with HNO3 in this case it forms sulfuric acid Water and nitrogen dioxide. So again
oxygen is being added to nitrogen so it leads to the
oxidation and this process in this case HNO3 is acting as an
oxidizing agent Now the action of HNO3 on metals. The metals reacts with HNO3 in different manner when they react with dilute HNO3 and concentrated HNO3. So, when the metals reacts with dilute nitric acid they
form the corresponding salt, water and release nitrogen monoxide
gas. So remember whenever metals react with dilute HNO3, they form the salt, water
and they release NO that is nitric oxide or nitrogen
Monoxide. But when metals react with concentrated HNO3, so in this case the metals copper, zinc they react with concentrated HNO3, in
this case they always release nitrogen dioxide gas. so with dilute acids metals form nitrogen monoxide or nitric oxide with concentrated HNO3 metals always form nitrogen dioxide gas. So
we can summarize it metals react with dilute HNO3 to form salt, water and nitric oxide that is NO and metals react with concentrated HNO3 to form salt, water and
nitrogen dioxide gas. So keep in mind the difference when the metals react with Dilute HNO3 they release nitric
oxide when they react with concentrated HNO3 they
release nitrogen dioxide gas. So nitric acid acts as an oxidizing Agent. We see whenever nitric acid reacts with the non-metals or metals oxygen is added to the metals or the non-metals so it leads to
the oxidation process and thus nitric acid is known as oxidizing agent or it
acts as an oxidizing agent. Complete this reaction, we have copper it’s reacting with HNO3. So
whenever you see a metal reacting with nitric acid first see whether it is dilute or concentrated nitric
acid in this case we have concentrated
nitric acid. So when copper reacts with concentrated
nitric acid it forms the corresponding salt, water and since there is concentrated nitric acid it releases nitrogen dioxide gas. So now lets balance the equation So whenever a metal reacts with concentrated nitric acid it forms the
corresponding salt, Water and releases nitrogen dioxide gas. Now we look at the effect of heat on the different
nitrates. the different nitrates have different
effects of heat. Let’s see. The alkali metal nitrates Whenever we heat the alkali metal nitrates they form the corresponding
nitrites and release oxygen gas. So we know sodium, potassium They are alkali metals. SO, when they are heated they form the corresponding nitrites sodium nitrite, potassium nitrite they form the corresponding nitrites
and release oxygen gas. What about other
metals. Other metallic nitrates, when they are heated except keep in mind this includes all the nitrates
except silver and mercury. So all the other nitrates except silver and
Mercury when they are heated they form the
corresponding oxides they release oxygen gas and nitrogen di-oxide gas is also
evolved. So, all the other nitrates except the alkali metal nitrates and silver and mercury they form the
corresponding oxides they release oxygen gas and nitrogen
dioxide gas when they are heated now how does silver and mercury nitrates are affected on heating So when silver and mercury nitrates are heated they form the corresponding metals. So, on
heating they form the metals and the gases evolved
remains the same that is they release oxygen and nitrogen
dioxide Gas. So, when the alkali metal nitrates they are heated they form the corresponding nitrites and
oxygen gas All other nitrates except silver and
mercury when they are heated they form the corresponding Oxides, oxygen gas and nitrogen dioxide gas is
released and silver and mercury When the silver and mercury nitrates are heated they form the corresponding metals that is good silver and mercury and they
release the same gases that is oxygen and nitrogen dioxide. Let me tell you a story a true story
this happened during second world war a scientist named George de Hevesy Was in his lab in Denmark. At the time Denmark was captured by the Germans. He
had illegally smuggled two Nobel Prize medals from Germany. He
was in is lab outside there were Nazi forces. It was only
a matter of few hours before the Nazis entered the
lab and searched the entire lab. So, he was
really scared If the Nazis found out that he had the
Nobel Prize with him they would kill him. So he
wanted to hide the Nobel prizes but he did not how to hide it should he
hide it under the table, should he hide it inside some books Well in that case if the lab is thoroughly
searched he would be killed because the Nazis
would find out. So he started looking for some solutions. He thought what to do and then it clicked to him. Gold is very stable in
nature it can not be dissolved in most of the
acids but a particular substance, a mixture of concentrated hydrochloric acid and concentrated nitric acid, this
mixture known as aqua regia dissolves even most unreactive
metals like gold. So this is what George did. He
dissolved the Nobel prize medals in this aqua regia. Gold can be recovered from this
aqua regia so he was hopeful that once the war gets over he would
come back and recover the gold from this aqua regia. Well it actually
happened that when the war gets over it was found out that the Nazis
despite careful searching of the lab, they could not
find out this gold. So they discovered this aqua regia, gold was recovered and recoined to the original
owners of the Nobel Prize medals. So this is
how aqua regia saved two Nobel prize
medals from the Nazis. How does aqua regia work? Well aqua regia is actually a mixture of 3 parts of concentrated hydrochloric acid and one part concentrated nitric acid. So when we take 3 parts of concentrated HCL and one part concentrated HNO3.
This mixture is known as aqua regia. When they react they form NaCl, water and they nascent chlorine Now this nascent chlorine is very reactive. It reacts with the most unreactive metals like platinum and gold. So nascent chlorine can react with these metals and make
them soluble. So with Platinum it forms PtCl4, with gold it forms AuCl3. So, the gold Nobel Prize medals they were
dissolved in this aqua regia as they form the
soluble AuCl3. So this is how aqua regia works. Now lets test the nitrates or the nitric acid Whenever a mixture contains nitrates or whenever we have a colorless
solution which we have to test for nitric acid we do a particular test known as a brown
ring test. Let’s see how it is carried out. So we take nitric acid or in case we
have a nitrate solution we take that solution. Now, we add some ferrous sulfate, ferrous sulfate is green in color then
we add some concentrated sulfuric acid So we add these 3, we heat the mixture and then it is allowed to cool for
sometime. So it is observed that the brown ring is formed in the center. So, this confirms that the colorless solution
was nitric acid or it contain a nitrate. So this
test is known as the brown ring test. This is
a test for nitric acid or for nitrates.

45 Replies to “Nitric Acid: Chemical Properties

  1. thanks for this because you made many dreams come true for many people-pilla venkat vineeth kumar

  2. R u kidding me….all i came for on this video was to learn how to balance an equation so tht i dont hv to cram it….but all u did was like…so lets balance the equation nd just wrote the numbers…no explanations whtsoever….all u were doing in the whole video was just reading off the smart board…no explanation for anything at all….huge disappointment

  3. Mam, on internet different sites are showing different reactions with HNO3.

    Whom should I follow?

    PLEASE MAM HELP ME.๐Ÿ˜ญ๐Ÿ˜ญ๐Ÿ˜ญ๐Ÿ˜ญ

  4. Thank you so much Thank you so much. Khuda apko Humesha khush rakhe , Mera to problem hee solve hogya

  5. Thank u mam. I have this ch in my portion for Monday's exam. U clarified all my doubts .. thn ma'm..

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