HomeSS 2ChemistryOxygen and Its Compounds

Oxygen and Its Compounds

Subject :Chemistry

Term : Second Term

Week :Week 4

Topic :

Behavioural Objectives :By the end of the lesson, students will be able

  1. To introduce students to the general properties of the Oxygen family and its compounds.
  2. To provide an understanding of the electronic structure and bonding of Oxygen.
  3. To familiarize students with the laboratory preparation of Oxygen.

Materials Needed:

  • Whiteboard and markers
  • Handouts with information on the topic
  • Multimedia resources, such as videos and interactive presentations
  • Laboratory equipment, such as test tubes, flasks, delivery tubes, and heating sources

 

Content

OXYGEN AND ITS COMPOUNDS

TOPIC: OXYGEN AND ITS COMPOUNDS

CONTENT

  • General Properties of Oxygen Family.
  • Electronic Structure and Bonding in Oxygen.
  • Preparation, Properties and Uses of Oxygen.
  • Oxides: Classification

 

Oxygen is the most abundant element on earth. It constitutes 21% by volume of atmospheric air.

 

Occurrence: It occurs as free elements in nature and in combined states.

Oxygen is a chemical element with the symbol O and atomic number 8. It is a highly reactive, colorless, odorless, and tasteless gas that forms about 21% of the Earth’s atmosphere. Oxygen is also the third-most abundant element in the universe, after hydrogen and helium.

Oxygen has many important compounds, including water (H2O), carbon dioxide (CO2), and ozone (O3). Here are some examples of oxygen compounds and their uses:

  1. Water (H2O) – Water is a compound made up of two hydrogen atoms and one oxygen atom. It is essential for all life on Earth and is used for many purposes, such as drinking, cleaning, and agriculture.
  2. Carbon dioxide (CO2) – Carbon dioxide is a compound made up of one carbon atom and two oxygen atoms. It is a greenhouse gas that contributes to climate change, but it is also important for photosynthesis in plants.
  3. Ozone (O3) – Ozone is a molecule made up of three oxygen atoms. It is found in the Earth’s upper atmosphere and helps to protect us from harmful ultraviolet radiation from the sun.
  4. Hydrogen peroxide (H2O2) – Hydrogen peroxide is a compound made up of two hydrogen atoms and two oxygen atoms. It is a powerful oxidizer and is used as a disinfectant and in the production of various chemicals.
  5. Rust (Fe2O3) – Rust is a compound made up of two iron atoms and three oxygen atoms. It forms on iron and steel when they are exposed to oxygen and water, and can weaken or destroy the metal.

These are just a few examples of the many important oxygen compounds. Oxygen and its compounds are essential to life and have many important uses in industry, medicine, and other fields

Evaluation

  1. What is the chemical symbol for oxygen? A) Oh B) O C) On D) Ox
  2. What percentage of the Earth’s atmosphere is oxygen? A) 78% B) 21% C) 10% D) 5%
  3. Which of the following is an oxygen compound? A) H2SO4 B) NH3 C) CO2 D) NaCl
  4. Which of the following is an example of an oxygen compound used in medicine? A) H2O2 B) CO2 C) NaCl D) CaO
  5. What is the chemical formula for water? A) H2SO4 B) HCl C) H2O D) NaCl
  6. What is the chemical formula for carbon dioxide? A) CO2 B) H2O C) NaCl D) O2
  7. What is the main function of ozone in the Earth’s atmosphere? A) It absorbs harmful ultraviolet radiation from the sun B) It provides oxygen for humans to breathe C) It regulates the Earth’s temperature D) It prevents the formation of hurricanes
  8. Which of the following is an example of an oxygen compound used in agriculture? A) H2O B) CO2 C) NaCl D) NH3
  9. What is the chemical formula for hydrogen peroxide? A) H2SO4 B) H2O2 C) NaCl D) CO2
  10. What is rust? A) A compound made up of iron and oxygen B) A compound made up of sodium and chlorine C) A compound made up of carbon and oxygen D) A compound made up of nitrogen and hydrogen

GENERAL PROPERTIES OF OXYGEN FAMILY

Elements in group VI include: Oxygen (O), Sulphur (S), Selenium (Se), Tellurium (Te), and Polonium (Po).their properties are as follows:

  1. They are non-metals and exist as solid at room temperature except for oxygen
  2. They are electron acceptors and oxidizing in nature.
  3. They do not react with water in any form. But oxygen and sulphur combine directly with hydrogen to yield water and hydrogen sulphide respectively.

 

ELECTRONIC STRUCTURE AND BONDING IN OXYGEN

Oxygen has an atomic number of 8; hence its electronic configuration is 1s22s22p4. This shows that oxygen needs two electrons in order to attain an octet configuration.

 

Oxygen atom has six valence electrons and can acquire a stable octet configuration by:

  1. Accepting two electrons from electropositive elements like metals to form negative oxide ion, O2-. Example

Ca2+ +  O2- → CaO

  1. Entering into covalent bond formation with non-metals by covalently sharing two out of its six outer electrons. Example formation of carbon (IV) oxide molecule.

O   C     O

  1. Forming covalent bond with itself.

O     O

The Oxygen family is a group of elements in the periodic table that includes oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and polonium (Po). These elements have similar chemical properties due to their shared electron configuration, with six valence electrons in the outermost shell. Here are some general properties of the Oxygen family:

  1. Oxidation state – The elements in the Oxygen family have a tendency to form compounds in which they exhibit a negative two oxidation state. For example, oxygen usually forms compounds with a -2 oxidation state, such as water (H2O) and carbon dioxide (CO2), while sulfur typically forms compounds with a -2 oxidation state, such as sulfur dioxide (SO2) and hydrogen sulfide (H2S).
  2. Electronegativity – The elements in the Oxygen family have high electronegativity values, meaning they have a strong tendency to attract electrons towards themselves. Oxygen is the most electronegative element in the family, followed by sulfur, selenium, tellurium, and polonium.
  3. Reactivity – The Oxygen family elements are highly reactive and tend to form compounds with other elements, such as metals, nonmetals, and other Oxygen family elements. For example, oxygen readily reacts with many metals to form oxides, while sulfur reacts with metals to form sulfides.
  4. Allotropy – Some elements in the Oxygen family exhibit allotropy, meaning they can exist in multiple forms or phases. For example, oxygen exists as a diatomic molecule (O2) at room temperature and pressure, but it can also exist as ozone (O3) under certain conditions. Sulfur also exhibits allotropy, with several different forms of solid sulfur existing, such as rhombic sulfur and monoclinic sulfur.
  5. Biological importance – Elements in the Oxygen family are essential for life, with oxygen being a key component of many biological molecules, such as water and carbohydrates. Sulfur is also an important element in biological systems, with some amino acids containing sulfur atoms.

These are just a few of the general properties of the Oxygen family. Understanding these properties can help us to better understand the behavior and reactivity of these elements, and their role in various chemical and biological processes

Evaluation

  1. Which of the following is not an element in the Oxygen family? A) Oxygen B) Carbon C) Sulfur D) Selenium
  2. What is the typical oxidation state of the elements in the Oxygen family? A) +2 B) +1 C) 0 D) -2
  3. Which of the following is the most electronegative element in the Oxygen family? A) Oxygen B) Sulfur C) Selenium D) Polonium
  4. Which element in the Oxygen family is known for its allotropy? A) Oxygen B) Sulfur C) Selenium D) Tellurium
  5. Which of the following is an example of an Oxygen family element exhibiting allotropy? A) Carbon B) Oxygen C) Nitrogen D) Hydrogen
  6. Which of the following is an example of an Oxygen family compound used in medicine? A) Water B) Carbon dioxide C) Sulfuric acid D) Selenium sulfide
  7. Which of the following is a key component of many biological molecules and is essential for life? A) Oxygen B) Sulfuric acid C) Carbon dioxide D) Hydrochloric acid
  8. Which Oxygen family element is used in the manufacture of sulfuric acid? A) Oxygen B) Sulfur C) Selenium D) Tellurium
  9. Which of the following is an example of an Oxygen family element that is used in the semiconductor industry? A) Oxygen B) Sulfur C) Selenium D) Polonium
  10. Which element in the Oxygen family is radioactive and has limited industrial uses? A) Oxygen B) Sulfur C) Selenium D) Polonium

LABORATORY PREPARATION OF OXYGEN

  1. By the thermal decomposition of potassium trioxochlorate (V) in the presence of MnO2 as catalyst

2KClO3(s)heat            2KCl2(s) +  3O2(g)

  1. By decomposition of hydrogen peroxide, H2O2 in the presence of MnO2 as catalyst

2H2O2(aq) heat 2H2O(l)  +  O2(g)

Hydrogen peroxide also reacts with acidified KMnO4 in the cold to produce oxygen

5H2O2(aq)   +  2KMnO4(aq)      +     3H2SO4(aq) K2SO4(aq) + 2MnSO4(aq)  +   8H2O(l)  +  502(g)

NOTE: If the gas is required dry, it is passed through anhydrous calcium chloride or concentrated tetraoxosulphate (VI) acid and collected over mercury.

 

INDUSTRIAL PREPARATION

  1. Electrolysis of water
  2. Fractional distillation of liquid air: This preparation involves two main processes: 

Liquefaction of air

Air is first passed through caustic Soda, NaOH(aq) to remove CO2.  It is then subjected through series of compressions, expansions and cooling until liquid air is obtained at -200oC.

Fractional distillation of liquid air

The liquid air is led to a fractional distillation column.  On distillation, nitrogen with a lower boiling point of -1960C is evolved first, leaving behind liquid oxygen.  Further heating converts the liquid oxygen to a gas at -1830C

EVALUATION

  1. Explain the laboratory preparation of oxygen
  2. By what process is oxygen obtained from air

 

PHYSICAL PROPERTIES

  1. It is colourless , odorless and tasteless diatomic gas
  2. It is neutral to litmus
  3. It is slightly soluble in water
  4. Gaseous oxygen is denser than air
  5. Gaseous oxygen liquefies at -1830C

 

CHEMICAL PROPERTIES

  1. 1. Reaction with metals: Oxygen combines directly with most metals to form basic oxides

2Ca + O2 2CaO

4K + O2 K2O 

The oxides of very electropositive metals, K, Na, Ca dissolves in water to form alkalis

2 K2O + 2 H2O 4KOH

  1. Reaction with non-metals: Non-metals burn in oxygen to acidic oxides.  These are known as acid anhydrides as they dissolve in water to form acids.

S(s) + O2(g) SO2(g)

SO2(g) + H2O(l)     H2SO3(aq)

P4(s)   + O2(g) P4O6(g)

P4O6   + H2O(l) 4H3PO3(aq)

  1. Most hydrocarbon and compounds of carbon, hydrogen and oxygen burn in oxygen to give CO2 and H2O

C2H5OH(l) + 3O4(g) 2CO2(g) +   3H2O(l)

 

USES OF OXYGEN

  1. It is used in oxy-ethylene flame
  2. It is required for respiration
  3. It is used in steel industry for the removal of C, S and P impurities from pig iron
  4. Liquid oxygen and fuel are used as propellant for space rockets
  5. Oxygen is used in the manufacturer of tetraoxosulphate (VI), trioxonitrate (VI) acid and ethanoic acid.

 

TEST FOR OXYGEN

When a glowing splinter is inserted into a gas jar containing an unknown gas and the glowing splinter is rekindled, then the gas is likely oxygen gas or dinitrogen (I) oxide gas. 

If the gas is colourless and reacts with nitrogen (II) oxide to produce reddish-brown fumes of nitrogen (IV) oxide, then the gas is confirmed to be oxygen gas.

 

EVALUATION

  1. State two physical properties of oxygen
  2. Using equation only, state two chemical properties of oxygen

 

OXIDES 

Oxides are binary compounds formed when oxygen combines with other elements

Types of oxides (classification)

  1. Basic Oxides: These are oxides of metals e.g. Na2O, K2O, MgO, CaO etc. They react with acids to form salt and water only. Example

Na2O(s) + 2HCl(aq) 2NaCl(s) + H2O(l)

  1. Acidic Oxides: These are oxides of non-metals which dissolves in water to form acids e.g. CO2, SO2, NO2 etc. They react with alkali to form a salt and water only e.g. CO2(g)   +   2NaOH(aq) Na2CO3(aq)   + H2O(l)
  2. Amphoteric Oxides: These are oxides of metals which can react with both acids and alkalis to form salt and water only.  They include the oxides of Al, Zn, Pb and Sn. Example

ZnO(s)    +   H2SO4 ZnSO4(aq)  +     H2O(l)

ZnO(s)    +    2NaOH(aq)    +  H2O Na2Zn(OH)4(aq)

  1. Neutral Oxides: These are oxides of non-metals which are neither acidic nor basic.  They are neutral to litmus.  They include CO2H2O and N2O
  2. Peroxides: These are oxides which contain higher proportion of oxygen than ordinary oxides e.g Na2O2, CaO2 and BaO2.  They react with dilute acid to produce hydrogen peroxide, H2O2

 

GENERAL EVALUATION/REVISION

  1. Mention four air pollutants and state their effects
  2. State two air pollution control measures
  3. Mention four types of oxides and give two examples each.
  4. Describe the electrolysis CuSO4(aq) using platinum electrodes
  5. Using equations only, state the products of the electrolysis of brine

ELECTRONIC STRUCTURE AND BONDING IN OXYGEN

The electronic structure and bonding of oxygen can be explained by looking at its electron configuration and the types of bonds it forms with other elements.

Oxygen has six electrons in its outermost shell, which are known as valence electrons. These electrons are involved in bonding with other atoms to form compounds. The electron configuration of oxygen is 1s2 2s2 2p4, which means it has two electrons in its innermost shell, two electrons in its second shell, and four electrons in its third shell.

Oxygen tends to form covalent bonds, in which it shares electrons with other elements to form molecules. In a covalent bond, two atoms share a pair of electrons. Oxygen can form single, double, and triple bonds with other elements, depending on the number of electrons it shares.

For example, in water (H2O), oxygen forms two single bonds with two hydrogen atoms, sharing one electron with each hydrogen. In carbon dioxide (CO2), oxygen forms two double bonds with one carbon atom, sharing two electrons with each carbon. In ozone (O3), oxygen forms one single bond and one double bond with two other oxygen atoms, sharing one and two electrons respectively.

The bonding in oxygen molecules is also influenced by its electronegativity, which is a measure of its ability to attract electrons. Oxygen has a high electronegativity value, which means it attracts electrons strongly towards itself. This results in polar covalent bonds, in which electrons are shared unequally between atoms.

For example, in water, the oxygen atom has a stronger pull on the shared electrons than the hydrogen atoms, resulting in a slightly negative charge on the oxygen and a slightly positive charge on the hydrogen atoms.

Understanding the electronic structure and bonding of oxygen is important for understanding its chemical properties and the behavior of compounds that contain oxygen

 

Evaluation

  1. How many electrons does oxygen have in its outermost shell? A) 2 B) 4 C) 6 D) 8
  2. What is the electron configuration of oxygen? A) 1s2 2s2 2p4 B) 1s2 2s2 2p6 C) 1s2 2s1 2p6 D) 1s2 2s1 2p4
  3. What type of bonds does oxygen tend to form? A) Ionic bonds B) Covalent bonds C) Metallic bonds D) Van der Waals bonds
  4. What is the maximum number of covalent bonds oxygen can form? A) 1 B) 2 C) 3 D) 4
  5. Which of the following is an example of a compound in which oxygen forms a single bond? A) Carbon dioxide (CO2) B) Ozone (O3) C) Water (H2O) D) Hydrogen peroxide (H2O2)
  6. What is electronegativity? A) The tendency of an atom to lose electrons B) The measure of an atom’s ability to attract electrons towards itself C) The strength of the bond between two atoms D) The energy required to remove an electron from an atom
  7. How does oxygen’s electronegativity influence its bonding with other elements? A) It results in nonpolar covalent bonds B) It results in metallic bonds C) It results in polar covalent bonds D) It results in ionic bonds
  8. What is the charge on the oxygen atom in a water molecule? A) Positive B) Negative C) Neutral D) It depends on the pH of the solution
  9. Which of the following is an example of an element that can form a double bond with oxygen? A) Hydrogen B) Carbon C) Nitrogen D) Sodium
  10. What is the shape of an oxygen molecule? A) Linear B) Trigonal planar C) Tetrahedral D) Octahedral

READING ASSIGNMENT

New School Chemistry for Senior Secondary School by O.Y.Ababio (6th edition) pages 368-373

 

WEEKEND ASSIGNMENT

SECTION A: Write the correct option ONLY

  1. The most abundant element on earth is a. nitrogen b. helium c. silicon d. oxygen 
  2. Determination of the proportion of oxygen in air can be done by passing a given volume of air through a. lime water b. alkaline pyrogallol solution c. FeSO4 solution 
  3. concentrated H2SO4
  4. Which one of the following is an amphoteric oxide? a. SiO2 b.  Al2O3 c. CuO d. K2O
  5. Most acid anhydrides react with water to form acids. Which of these is a mixed anhydride? a. N2O b. NO c. NO2 d. SO2
  6. A gas which is neutral to litmus and rekindles a glowing splinter is
  7. O2 b. O3 c. H2O2 d. H2

 

SECTION B

  1. Using diagram ONLY, describe the preparation of dry oxygen gas in the laboratory
  2. Why is oxygen collected over mercury?

Oxygen is a gas that is essential for life and has many industrial applications. Here are the steps involved in the laboratory preparation of oxygen:

  1. Materials: The materials needed for the preparation of oxygen include a source of oxygen-containing compound, such as potassium chlorate (KClO3), a test tube or flask, a heating source, a delivery tube, a water bath, and a collecting vessel.
  2. Set up the apparatus: The apparatus is set up by placing the source of oxygen-containing compound, such as KClO3, in the test tube or flask, and heating it with a heating source. The delivery tube is attached to the test tube or flask, and the other end of the delivery tube is placed in the collecting vessel.
  3. Heat the compound: The source of oxygen-containing compound, such as KClO3, is heated until it decomposes, releasing oxygen gas. The reaction can be written as follows: 2KClO3(s) → 2KCl(s) + 3O2(g)
  4. Collect the oxygen gas: The oxygen gas is collected in the collecting vessel by displacement of water. The delivery tube is placed in a water bath, and the end of the delivery tube is submerged in the water. As the oxygen gas is produced, it displaces the water in the collecting vessel and collects in the space above the water.
  5. Purify the oxygen gas: The oxygen gas collected may contain impurities, such as water vapor or nitrogen. The oxygen gas is purified by passing it through a drying agent, such as calcium chloride (CaCl2), which absorbs any water vapor, and then through a column of activated alumina or molecular sieve, which removes any remaining impurities.
  6. Test the purity of the oxygen gas: The purity of the oxygen gas can be tested using a glowing splint test. A glowing splint is placed in a sample of the oxygen gas. If the oxygen gas is pure, the splint will burst into flames.

In conclusion, laboratory preparation of oxygen is a simple and straightforward process that can be done using readily available materials. The resulting oxygen gas can be used for a variety of purposes, from supporting combustion to supporting life.

 

Evaluation

  1. What is the source of oxygen-containing compound commonly used in the laboratory preparation of oxygen? A) Sodium chloride B) Potassium chloride C) Calcium chloride D) Magnesium chloride
  2. What is the chemical equation for the decomposition of potassium chlorate to form oxygen gas? A) 2KClO3(s) → 2KCl(s) + 3O(g) B) 2KClO3(s) → 2KCl(s) + 3O2(g) C) 2KCl(s) + 3O2(g) → 2KClO3(s) D) 2KCl(s) + 3O(g) → 2KClO3(s)
  3. What is the purpose of the delivery tube in the laboratory preparation of oxygen? A) To heat the oxygen-containing compound B) To collect the oxygen gas C) To filter the oxygen gas D) To purify the oxygen gas
  4. How is the oxygen gas collected in the laboratory preparation of oxygen? A) By displacement of water B) By filtration C) By evaporation D) By sublimation
  5. What is the purpose of passing the oxygen gas through a drying agent in the laboratory preparation of oxygen? A) To remove impurities B) To absorb water vapor C) To purify the oxygen gas D) To filter the oxygen gas
  6. What is the purpose of passing the oxygen gas through a column of activated alumina or molecular sieve in the laboratory preparation of oxygen? A) To remove impurities B) To absorb water vapor C) To purify the oxygen gas D) To filter the oxygen gas
  7. How is the purity of the oxygen gas tested in the laboratory preparation of oxygen? A) By using a glowing splint test B) By using a litmus paper test C) By using a spectrometer D) By using a calorimeter
  8. What happens to the water in the collecting vessel during the laboratory preparation of oxygen? A) It remains in the vessel B) It is converted to steam C) It is displaced by the oxygen gas D) It is absorbed by the oxygen gas
  9. What is the purpose of heating the oxygen-containing compound in the laboratory preparation of oxygen? A) To decompose the compound and release oxygen gas B) To purify the compound C) To make the compound more reactive D) To make the compound more stable
  10. What is the purpose of the water bath in the laboratory preparation of oxygen? A) To cool the reaction vessel B) To heat the reaction vessel C) To prevent the reaction vessel from breaking D) To prevent the delivery tube from clogging

 

Lesson Plan Presentation: Oxygen and Its Compounds

Grade Level: SS 2

Time Frame: 60 minutes

Procedure:

  1. Introduction (5 minutes)
  • Begin the class by asking students what they know about Oxygen and its compounds.
  • Explain the objective of the lesson and what they can expect to learn.
  1. General Properties of the Oxygen Family and its Compounds (20 minutes)
  • Use multimedia resources to present the general properties of the Oxygen family and its compounds, such as its oxidation state, electronegativity, reactivity, allotropy, and biological importance.
  • Provide examples of Oxygen family compounds and their uses, such as water, carbon dioxide, and sulfuric acid.
  • Use a whiteboard to illustrate the structure and properties of Oxygen family compounds.
  1. Electronic Structure and Bonding in Oxygen (20 minutes)
  • Explain the electronic structure of Oxygen and its valence electrons.
  • Discuss the types of bonds Oxygen forms, such as covalent bonds, and how electronegativity influences bonding.
  • Use examples to illustrate the types of bonds Oxygen forms, such as water, carbon dioxide, and ozone.
  • Use a whiteboard to illustrate the electronic structure and bonding in Oxygen.
  1. Laboratory Preparation of Oxygen (15 minutes)
  • Explain the laboratory preparation of Oxygen, including the materials needed and the steps involved.
  • Demonstrate the laboratory preparation of Oxygen using laboratory equipment.
  • Emphasize safety precautions that should be taken during the laboratory preparation of Oxygen.
  1. Conclusion (5 minutes)
  • Recap the main points covered in the lesson.
  • Ask students if they have any questions or concerns.
  • Provide handouts with information on the topic for students to review.

Assessment:

  • Ask students to complete a worksheet or quiz to test their understanding of the topic.
  • Evaluate students based on their participation and engagement during the lesson.
  • Evaluate students based on their performance in the laboratory preparation of Oxygen.

Weekly Assessment /Test 

  1. What is the general formula of the Oxygen family?
  2. What is the typical oxidation state of Oxygen family elements?
  3. Which Oxygen family element is the most electronegative?
  4. What is allotropy and which Oxygen family element exhibits allotropy?
  5. Give an example of an Oxygen family compound used in medicine.
  6. What type of bond does Oxygen tend to form with other elements?
  7. How does Oxygen’s electronegativity influence its bonding with other elements?
  8. What is the purpose of passing Oxygen gas through a drying agent and a column of activated alumina or molecular sieve during laboratory preparation?
  9. What is the chemical equation for the decomposition of Potassium Chlorate to form Oxygen gas?
  10. How is the purity of the Oxygen gas tested during laboratory preparation?
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