Lecture Notes Week 13 (CHM 101) 2023-2024 PDF

PAMANTASAN NG CABUYAO KATAPATAN HOMES, BANAY-BANAY, CABUYAO LAGUNA College of Arts and Sciences COURSE CODE: CHM 101 (Inorganic Chemistry) COURSE DESCRIPTION:...

PAMANTASAN NG CABUYAO KATAPATAN HOMES, BANAY-BANAY, CABUYAO LAGUNA College of Arts and Sciences COURSE CODE: CHM 101 (Inorganic Chemistry) COURSE DESCRIPTION: The course covers the fundamental concepts and principles of Inorganic Chemistry, blending facts with theories in application, particularly in various fields of students' interests and generally to the physical world. Emphasis is given to the correlation of present concepts of atomic composition and structure the physical and chemical properties of elements and compounds. COURSE INTENDED 1. Apply concepts and ideas to everyday life situations. LEARNING OUTCOMES 2. Develop interest and shows appreciation in the course and be aware of the practical applications and social implications of the knowledge gained especially in the care and protection of the environment. LEARNING MATERIAL FOR WEEK: 13 I TITLE: Chemical Equations II OBJECTIVES: After the lesson, the students are expected to: 1. describe the chemical reaction in terms of chemical equations. 2. identify the different types of chemical reactions. 3. write a complete and balance equation. III INTRODUCTION: Chemical equation is a short way of expressing chemical change in terms of symbols and formulas. It is the symbolic representation of a chemical reaction. This example illustrates the fundamental aspects of any chemical equation: 1. The substances undergoing reaction are called reactants, and their formulas are placed on the left side of the equation. 2. The substances generated by the reaction are called products, and their formulas are placed on the right sight of the equation. 3. Plus signs (+) separate individual reactant and product formulas, and an arrow (⟶) separates the reactant and product (left and right) sides of the equation. 4. The relative numbers of reactant and product species are represented by coefficients (numbers placed immediately to the left of each formula). A coefficient of 1 is typically omitted. IV CONTENTS: Symbols in Writing an Equation Symbol Meaning Symbol Meaning “Yields” – indicates the Used to indicate gaseous result of the reaction product Reversible reaction catalyst Catalyst is used ∆ Heat is applied + Separates two or more reactants or products Used to indicate NR Means no reaction takes precipitate place LECTURE NOTES COMPILATION Page 1 of 5 1ST SEMESTER AY 2023-2024  PAMANTASAN NG CABUYAO KATAPATAN HOMES, BANAY-BANAY, CABUYAO LAGUNA College of Arts and Sciences Balancing chemical equations gives us an idea about the quantity of chemical reactants that are needed for the reaction. Without balancing, we just know what kind of products are obtained but with balancing chemical reactions we can also know the weight of substance produced. According to the law of conservation of mass, when a chemical reaction occurs, the mass of the products should be equal to the mass of the reactants. Therefore, the amount of the atoms in each element does not change in the chemical reaction. As a result, the chemical equation that shows the chemical reaction needs to be balanced. A balanced chemical equation occurs when the number of the atoms involved in the reactants side is equal to the number of atoms in the products side. Example: N2 + H2 → NH3 Reactants Product In this chemical reaction, nitrogen (N2) reacts with hydrogen (H) to produce ammonia (NH 3). The reactants are nitrogen and hydrogen, and the product is ammonia. If we look at this equation, we can see that the equation is not balanced. N2 + H2 → NH3 N=2 H=2 N=1 H=3 The equation is not balanced because in the reactants side, there are 2 nitrogen (N) atoms and 2 hydrogen (H) atoms. In the products side, there is 1 nitrogen (N) atom and 3 hydrogen (H) atoms. The number of the atoms is not balanced on both sides. To balance the chemical equation above, we need to make use of coefficients. A coefficient is a number that we place in front of a chemical formula. In the chemical equation, to make the number of nitrogen (N) atoms equal on both sides, first, we place a coefficient of 2 in front of NH3. N2 + H2 → 2NH3 N=2 H=2 N=2 H=6 Once we do that, the number of nitrogen (N) atoms on both sides is balanced. However, the number of hydrogen (H) atoms are not balanced on both sides. We need to make use of another coefficient in front of H 2. This time, we put a coefficient of 3 in front of H2 to balance the chemical equation. N2 + 3H2 → 2NH3 N=2 H=6 N=2 H=6 The equation above is now balanced. There are 2 nitrogen (N) atoms and 6 hydrogen (H) atoms on both the reactants and products side. Since there is no coefficient in front of N2, that means the coefficient is equal to 1. LECTURE NOTES COMPILATION Page 2 of 5 1ST SEMESTER AY 2023-2024  PAMANTASAN NG CABUYAO KATAPATAN HOMES, BANAY-BANAY, CABUYAO LAGUNA College of Arts and Sciences Types of Chemical Reactions: Many chemical reactions can be classified as one of five basic types. Having a thorough understanding of these types of reactions will be useful for predicting the products of an unknown reaction. The five basic types of chemical reactions are combination or direct union, decomposition, single-replacement, double-replacement, and combustion. Analyzing the reactants and products of a given reaction will allow you to place it into one of these categories. Some reactions will fit into more than one category. 1) Combination or Direct Union Reaction – also known as a synthesis reaction, is a reaction in which two or more substances combine to form a single new substance. Combination reactions can also be called synthesis reactions. The general form of a combination reaction is: A+ + B - → AB One combination reaction is two elements combining to form a compound. Solid sodium metal reacts with chlorine gas to product solid sodium chloride. 2Na + Cl2 → 2NaCl Notice that in order to write and balance the equation correctly, it is important to remember the seven elements that exist in nature as diatomic molecules (hydrogen – H2, oxygen – O2, nitrogen – N2, chlorine – Cl2, Bromine – Br2, fluorine – I2 and iodine – I2). One sort of combination reaction that occurs frequently is the reaction of an element with oxygen to form an oxide. Metals and nonmetals both react readily with oxygen under most conditions. Magnesium reacts rapidly and dramatically when ignited, combining with oxygen from the air to produce a fine powder of magnesium oxide. 2Mg + O2 → 2MgO 2) Decomposition Reaction – is a reaction in which a compound breaks down into two or more simpler substances. The general form of a decomposition reaction is: AB A + B ∆ Most decomposition reactions require an input of energy in the form of heat (∆), light, or electricity. Binary compounds are compounds composed of just two elements. The simplest kind of decomposition reaction is when a binary compound decomposes into its elements. Mercury (II) oxide, a red solid, decomposes when heated to produce mercury and oxygen gas. 2HgO 2Hg + O2 ∆ 2MgO 2Mg + O2 ∆ A reaction is also considered to be a decomposition reaction even when one or more of the products is still a compound. A metal carbonate decomposes into a metal oxide and carbon dioxide gas. For example, calcium carbonate decomposes into calcium oxide and carbon dioxide. CaCO3 CaO + CO2 ∆ BaCO3 BaO + CO2 ∆ Metal hydroxides decompose on heating to yield metal oxides and water. Sodium hydroxide decomposes to produce sodium oxide and water. 2NaOH Na2O + H2O ∆ 2LiOH Li2O + H2O ∆ LECTURE NOTES COMPILATION Page 3 of 5 1ST SEMESTER AY 2023-2024  PAMANTASAN NG CABUYAO KATAPATAN HOMES, BANAY-BANAY, CABUYAO LAGUNA College of Arts and Sciences 3) Single Replacement Reactions - is a reaction in which one element replaces a similar element in a compound. The general form of a single-replacement (also called single-displacement) reaction is: A + BC → AC + B In this general reaction, element A is a metal and replaces element B, also a metal, in the compound. When the element that is doing the replacing is a nonmetal, it must replace another nonmetal in a compound, and the general equation becomes: Y + XZ → XY + Z Y is a nonmetal and replaces the nonmetal Z in the compound with X. In this reaction, activity of the metals must be determined using the activity series of the metals. Activity Series Metals Decreasing Activity Halogens Lithium Fluorine Potassium Chlorine Barium Bromine Calcium Iodine Sodium Magnesium Aluminum Zinc Iron Cadmium Nickel Tin Lead (Hydrogen) Copper Mercury Silver Gold Many metals react easily with acids, and when they do so, one of the products of the reaction is hydrogen gas. Zinc reacts with hydrochloric acid to produce zinc chloride and hydrogen. Zn + 2 HCl → ZnCl2 + H2 2Al + 6 HCl → 2AlCl3 + 3H2 Cu + HCl no reaction (n.r) 4) Double Replacement Reaction – is a reaction in which the positive and negative ions of two ionic compounds exchange places to form two new compounds. The general form of a double replacement (also called double- displacement) reaction is: AB + CD → AD + CB In this reaction, A and C are positively charged cations, while B and D are negatively charged anions. Double replacement reactions generally occur between substances in aqueous solution. In order for a reaction to occur, one of the products is usually a solid precipitate, a gas, or a molecular compound such as water. LECTURE NOTES COMPILATION Page 4 of 5 1ST SEMESTER AY 2023-2024  PAMANTASAN NG CABUYAO KATAPATAN HOMES, BANAY-BANAY, CABUYAO LAGUNA College of Arts and Sciences A precipitate form in a double replacement reaction when the cations from one of the reactants combine with the anions from the other reactant to form an insoluble ionic compound. When aqueous solutions of potassium iodide and lead (II) nitrate are mixed, the following reaction occurs. 2 KI + Pb(NO3)2 → 2KNO3 + PbI2 Ba(OH)2 + HsSO4 → BaSO4 + 2H2O 2 AlCl3 + Mg3(PO4)2 → 2 AlPO4 + 3 MgCl2 3 Li2CO3 + 2 FeCl3 → 6 LiCl + Fe2(CO3)3 5) Combustion Reactions – is a reaction in which a substance reacts with oxygen gas, releasing energy in the form of light and heat. Combustion reactions must involve O2 as one reactant. The combustion of hydrogen gas produces water vapor. 2H2 + O2 → 2H2O Notice that this reaction also qualifies as a combination reaction. Many combustion reactions occur with a hydrocarbon, a compound made up solely of carbon and hydrogen. The products of the combustion of hydrocarbons are always carbon dioxide and water. Many hydrocarbons are used as fuel because their combustion releases very large amount of heat energy. Propane (C3H8) is a gaseous hydrocarbon that is commonly used as the fuel source in gas grills. C3H8 + 5O2 → 3CO2 + 4H2O References: http://study.com https://chem.libretexts.org/ Copyright Notice Materials contained in the learning materials have been copied and conveyed to you by or on behalf of Pamantasan ng Cabuyao pursuant to Section IV- The Copyright Act (RA) 8293 of the Philippines Intellectual Property Code. You are not allowed by the Pamantasan ng Cabuyao to reproduce or convey these materials. The content may contain works which are protected by copyright under RA 8293. You may be liable to copyright infringement for any copying and/or distribution of the content and the copyright owners have the right to take legal actions against such infringement. Do not remove this notice. LECTURE NOTES COMPILATION Page 5 of 5 1ST SEMESTER AY 2023-2024