Testing For Hydrogen, Oxygen, Carbon Dioxide & Chlorine | Matter | Chemistry | FuseSchool
Summary
TLDRThis lesson teaches methods to identify common gases through laboratory testing. Hydrogen is confirmed by its squeaky pop sound when burned, indicating a combustion reaction with oxygen. Oxygen relights a glowing splint due to its higher concentration. Carbon dioxide extinguishes a lit splint and turns lime water milky, forming calcium carbonate. Ammonia turns damp red litmus paper blue and forms white ammonium chloride smoke with hydrochloric acid. Chlorine bleaches blue litmus paper red and white. These tests help distinguish gases that are otherwise colorless and odorless.
Takeaways
- 🔍 Gases like hydrogen, oxygen, carbon dioxide, ammonia, and chlorine cannot be identified by appearance alone due to their colorless and odorless nature.
- 🔥 To test for hydrogen, place a lit splint at the mouth of the reaction vessel to hear a 'squeaky pop', indicating its presence through combustion.
- 🌪️ A glowing splint will reignite in the presence of oxygen, which is a distinctive test for oxygen's presence in a reaction vessel.
- 💥 The 'squeaky pop' of hydrogen is due to a mini explosion caused by its high flammability and the combustion reaction with oxygen.
- 🌀 Carbon dioxide extinguishes a lit splint, but a more accurate test involves bubbling it through lime water, which turns milky due to calcium carbonate formation.
- 🌊 Ammonia extinguishes a lit splint and turns damp red litmus paper blue, indicating its presence through a chemical reaction.
- 🌫️ In the presence of concentrated hydrochloric acid, ammonia forms a white smoke of ammonium chloride, confirming its presence.
- 🔴 Chlorine turns damp blue litmus paper red and eventually bleaches it to white, a unique test for chlorine's presence.
- 🧪 Testing for gases in the laboratory is crucial because it is nearly impossible to determine a gas's identity by its appearance alone.
- 🌬️ The concentration of oxygen in a reaction vessel is higher than in air (21%), which is why a glowing splint relights in its presence.
- 📝 In conclusion, each gas has a unique test: hydrogen burns with a pop, oxygen reignites a glowing splint, carbon dioxide turns lime water milky, ammonia turns red litmus paper blue and forms ammonium chloride smoke, and chlorine bleaches blue litmus paper.
Q & A
Why is it difficult to identify a gas by its appearance alone?
-It is difficult because many gases, like hydrogen, oxygen, and carbon dioxide, are colorless and odorless, making them indistinguishable by sight or smell.
How can you confirm the presence of hydrogen in a reaction vessel?
-Place a lit splint at the mouth of the reaction vessel; a distinctive squeaky pop sound indicates the presence of hydrogen due to its combustion reaction with oxygen.
What property of hydrogen causes the squeaky pop sound when it burns?
-Hydrogen is highly flammable, and the pop sound is a result of a mini explosion caused by its rapid combustion in the presence of oxygen.
How do you test for the presence of oxygen in a reaction vessel?
-Place a glowing splint at the mouth of the reaction vessel; the splint will reignite in the presence of oxygen.
Why does a glowing splint reignite in the presence of oxygen?
-The glowing splint relights because the concentration of oxygen in the reaction vessel is higher than in air, which contains only 21% oxygen.
How can you differentiate between carbon dioxide and ammonia when both extinguish a lit splint?
-Bubble the gas through lime water (calcium hydroxide solution); carbon dioxide will turn the lime water milky due to the formation of calcium carbonate.
What happens when carbon dioxide is bubbled through lime water?
-Lime water turns milky in the presence of carbon dioxide because of the formation of calcium carbonate, which is a sign of carbon dioxide.
How does ammonia affect a damp red litmus paper?
-Ammonia turns damp red litmus paper blue, indicating its basic nature.
What reaction occurs when ammonia is exposed to concentrated hydrochloric acid?
-In the presence of concentrated hydrochloric acid, ammonia forms a white smoke of ammonium chloride, confirming its presence.
How can you test for the presence of chlorine gas?
-Chlorine gas turns damp blue litmus paper red and eventually bleaches it to white, indicating its presence.
What is the final conclusion of the lesson regarding the testing of different gases?
-The lesson concludes that hydrogen burns with a squeaky pop, oxygen relights a glowing splint, carbon dioxide turns lime water milky, ammonia turns damp red litmus paper blue and forms white smoke of ammonium chloride with concentrated hydrochloric acid, and chlorine turns damp blue litmus paper red and bleaches it to white.
Outlines
🔬 Laboratory Gas Testing Techniques
This paragraph introduces the necessity of gas testing in the laboratory due to the difficulty in identifying gases by appearance alone. It explains the colorless and odorless nature of gases like hydrogen, oxygen, and carbon dioxide, and the methods used to distinguish them. The paragraph details the testing process for hydrogen using a lit splint to produce a 'squeaky pop' sound, indicating the gas's presence through combustion. It also hints at the properties of hydrogen and oxygen that lead to these reactions, inviting the learner to reflect on why hydrogen burns with a pop and oxygen reignites a glowing splint.
Mindmap
Keywords
💡Hydrogen
💡Oxygen
💡Carbon Dioxide
💡Ammonia
💡Chlorine
💡Combustion Reaction
💡Lime Water
💡Litmus Paper
💡Concentrated Hydrochloric Acid
💡Ammonium Chloride
💡Bleaching
Highlights
Identifying gases by appearance is nearly impossible due to similarities like colorlessness and odorlessness.
Hydrogen is tested by placing a lit splint at the reaction vessel's mouth, resulting in a distinctive squeaky pop.
The squeaky pop confirms hydrogen's presence due to its combustion in oxygen, producing water.
Oxygen is tested with a glowing splint that relights in its presence, indicating higher oxygen concentration.
Hydrogen's flammability causes a mini explosion, resulting in the pop sound when tested.
Carbon dioxide extinguishes a lit splint but can be accurately tested with lime water, turning it milky due to calcium carbonate formation.
Ammonia extinguishes a lit splint and turns damp red litmus paper blue.
Ammonia's presence is confirmed by the formation of white smoke of ammonium chloride when in contact with concentrated hydrochloric acid.
Chlorine turns damp blue litmus paper red and eventually bleaches it to white, indicating its presence.
Gases tested include hydrogen, oxygen, carbon dioxide, ammonia, and chlorine, each with specific reactions for identification.
The importance of accurate testing methods for gases in the laboratory due to their similar physical properties.
Hydrogen combustion in oxygen is a key test for its presence, demonstrated by a unique sound.
A glowing splint is used to test for oxygen, as it relights in an environment with higher oxygen levels.
Carbon dioxide's reaction with lime water is a classic test, showing a visual change to milky color.
Ammonia's effect on litmus paper provides a simple test for its presence, turning red paper blue.
The interaction between ammonia and concentrated hydrochloric acid produces a visible white smoke, confirming ammonia.
Chlorine's bleaching effect on blue litmus paper is a definitive test for its detection.
In conclusion, specific reactions for each gas provide clear methods for identification in a laboratory setting.
Transcripts
in this lesson
we will learn how to test for the
presence of
hydrogen
oxygen
carbon dioxide ammonia and chlorine
we test for gases in the laboratory
because it is nearly impossible to
determine the identity of a gas just by
its appearance
as an example hydrogen oxygen and carbon
dioxide are all colorless and odorless
how would we be able to determine which
is which
to test for hydrogen place a lit splint
at the mouth of the reaction vessel
you should hear a very distinctive
squeaky pop which confirms its presence
this is due to the combustion reaction
of hydrogen in the presence of oxygen
creating water as the only product
to test for oxygen
place a glowing splint at the mouth of
the reaction vessel
keep in mind that the splint should be
glowing not lit
a glowing splint relights in the
presence of oxygen
why does hydrogen burn with a squeaky
pop
why does oxygen re-light the glowing
splint
hint recall some properties
of hydrogen and oxygen
please pause the lesson to think about
this and resume once you are done
hydrogen is highly flammable and
the pop sound that you hear is actually
a mini explosion
the glowing splint relights in the
presence of oxygen as there is a higher
concentration of oxygen in the reaction
vessel than compared with air which is
only 21 oxygen
carbon dioxide will extinguish a lit
splint but the same occurs in the
presence of ammonia
a more accurate test is to bubble carbon
dioxide through lime water which is an
aqueous solution of calcium hydroxide
also known as slaked lime
lime water turns milky in the presence
of carbon dioxide due to the formation
of calcium carbonate
ammonia extinguishes a lit splint and
turns damp red litmus paper blue
in the presence of concentrated
hydrochloric acid a white smoke will
form
this is ammonium chloride and confirms
the presence of ammonia
chlorine turns damp blue litmus paper
red and eventually bleaches it to white
in conclusion hydrogen burns with a
squeaky pop oxygen relights a glowing
splint and carbon dioxide turns lime
water milky
ammonia turns in damp red litmus paper
blue and forms a white smoke of ammonium
chloride in the presence of concentrated
hydrochloric acid
chlorine turns damp blue litmus paper
red and continues to bleach it to white
you
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