General Chemistry Notes (2024-2025/1 Semester) PDF

Faculty of Engineering General Chemistry CHEM1020 Dr. Mostafa Ghasemi Associate Professor 2024 – 2025/ I Semester  General Chemistry CHEM1020 Week 8 INTRODUCTION TO STOICHIOMETRY...

Faculty of Engineering General Chemistry CHEM1020 Dr. Mostafa Ghasemi Associate Professor 2024 – 2025/ I Semester  General Chemistry CHEM1020 Week 8 INTRODUCTION TO STOICHIOMETRY CALCULATE MOLARITY, MOLALITY, EQULIBRIUM CLO3 PLO1 CONSTANT,COLLIGATIVE PROPERTIES AND GAS PROPERTIESS TABULATE THE STOICHIOMETRIC BALANCE OF CHEMICAL CLO4 PLO4 EQUATIONS FORREACTANT AND PRODUCT QUANTITIES. Dr. Mostafa Ghasemi Associate Professor Chemical Engineering Faculty of Engineering  The Chemical Equation Chemical reactions always involve change. Atoms, molecules or ions rearrange to form new substances. The substances entering the reaction are called reactants. The substances formed in the reaction are called products. During reactions chemical bonds are broken and new bonds are formed. 3  A chemical equation is a shorthand expression for a chemical change or reaction. A chemical equation uses the chemical symbols and formulas of the reactants and products and other symbolic terms to represent a chemical reaction. 4  Chemical Equation Al + Fe2O3 Fe + Al2O3 reactants products iron oxygen aluminum oxygen bonds break bonds form 5 Coefficients (whole numbers) are placed in front of substances to balance the equation and to indicate the number of units (atoms, molecules, moles, or ions) of each substance that is reacting. 2 Al + Fe2O3 2 Fe + Al2O3 coefficient coefficient 6 Conditions required to carry out the reaction may be placed above or below the arrow.  2 Al + Fe2O3 2 Fe + Al2O3 coefficient coefficient  heat 7 In a chemical The physical state of a reaction atoms are substance is indicated neither created nor by symbols such as (l) destroyed. for liquid. (s) + Fe2O3(s) 2Fe(l) 2Al(s) (l) + Al2O3 (s) All atoms present in the reactant must also be present in the products. 8 Symbols Used in Chemical Reactions symbol + meaning plus placed between location substances 9  symbol meaning yields between reactants and location products 10  symbol (s) meaning solid location after formula 11  symbol (l) meaning liquid location after formula 12  symbol (g) meaning gas location after formula 13  symbol (aq) meaning aqueous location after formula 14  symbol  meaning heat location written above 15  symbol h meaning light energy location written above 16  symbol  meaning gas formation location after formula 17  Writing and Balancing Equations To balance an equation, adjust the number of atoms of each element so that they are the same on each side of the equation. Never change a correct formula to balance an equation. 18 Steps for Balancing Equations Step 1 Identify the reaction. Write a description or word equation for the reaction. Mercury (II) oxide decomposes to form mercury and oxygen. mercury(II) oxide → mercury + oxygen 19 Step 2 Write the unbalanced (skeleton) equation. – The formulas of the reactants and products must be correct. – The reactants are written to the left of the arrow and the products to the right of the arrow. HgO Hg + O2 The formulas of the reactants and products can never be changed. 20 Step 3a Balance the equation. – Count and compare the number of atoms of each element on both sides of the equation. – Determine the elements that require balancing. 21 Step 3a Balance the equation. HgO → Hg + O2 Element Reactant Side Product Side Hg 1 1 – There is one mercury atom on the reactant side and one mercury atom on the product side. – Mercury is balanced. 22 Step 3a Balance the equation. HgO Hg + O2 Element Reactant Side Product Side O 1 2 – There are two oxygen atoms on the product side and there is one oxygen atom on the reactant side. – Oxygen needs to be balanced. 23 Step 3b Balance the equation. – Balance each element one at a time, by placing whole numbers (coefficients) in front of the formulas containing the unbalanced element. A coefficient placed before a formula multiplies every atom in the formula by that number. 24 Step 3b Balance the equation. 2HgO Hg + O2 Element Reactant Side Product Side O 12 2 Place a 2 in front of HgO to balance O.  There are two oxygen atoms on the reactant side and there are two oxygen atoms on the product side.  Oxygen (O) is balanced. 25 Step 3c Balance the equation. Check all other elements after each individual element is balanced to see whether, in balancing one element, another element became unbalanced. 26 Step 3c Balance the equation. 2HgO Hg + O2 Element Reactant Side Product Side Hg 2 1 Count and compare the number of mercury (Hg) atoms on both sides of the equation. There are two mercury atoms on the reactant side and there is one mercury atom on the product side.  Mercury (Hg) is not balanced. 27 Step 3c Balance the equation. 2HgO 2Hg + O2 Element Reactant Side Product Side Hg 2 12 Place a 2 in front of Hg to balance mercury.  There are two mercury atoms on the reactant side and there are two mercury atoms on the product side.  Mercury (Hg) is balanced. 28   THE EQUATION IS BALANCED 2HgO 2Hg + O2 Element Reactant Side Product Side Hg 2 2 O 2 2 29  Types of Chemical Equations Combination Decomposition Single-Displacement Double-Displacement 1. Hein, M., Pattison, S., Arena, S., and Best, L. R. (2005). Introduction to General, Organic, and Biochemistry, 8th Edition John Wiley & sons 2. Silberberg, M. (2007), Principles of General Chemistry, 1st. Edition, McGraw Hill. 3. Olmsted, J.O and Williams, G. M. (2006) Chemistry, 4th Edition, John Wiley & sons  Combination Reactions Two reactants combine to form one product. A + B AB 31  Examples Metal + Oxygen → Metal Oxide 2Ca(s) + O2(g) 2CaO(s) 4Al(s) + 3O2(g) 2Al2O3(s) 32 Nonmetal + Oxygen → Nonmetal Oxide S(s) + O2(g) SO2(g) N2(g) + O2(g) 2NO(g) 33  Metal + Nonmetal → Salt 2K(s) + F2(g) 2KF(s) 2Al(s) + 3Cl2(g) 2AlCl3(s) 34  Metal Oxide + Water → Metal Hydroxide Na2O(s) + H2O(l) 2NaOH(aq) CaO(s) + 2H2O(l) 2Ca(OH) 2(aq) 35  Nonmetal Oxide + H2O(l) → Oxy-acid SO3(g) + H2O(l) H2SO4(aq) N2O5(g) + H2O(l) 2HNO3(aq) 36 Decomposition Reactions A single substance breaks down to give two or more different substances. AB A + B 37  Examples Metal Oxide → Metal + Oxygen 2Ag2O(s) 4Ag(s) + O2(g) Metal Oxide → Metal Oxide + Oxygen 2PbO2(s) 2PbO(s) + O2(g) 38  Carbonate → CO2(g) CaCO3(s) CaO(s) + CO2(g) Hydrogen carbonate → CO2(g) 2NaHCO3(s) Na2CO3(s) + H2O(g) + CO2(g) 39  Single Displacement Reactions One element reacts with a compound to replace one of the elements of that compound. A + BC AC + B 40  Metal + Acid → Hydrogen + Salt Mg(s) + HCl(aq) H2(g) + MgCl2(aq) salt 2Al(s) + 3H2SO4(aq) 3H2(g) + Al2(SO4)3(aq) salt 41 Metal + Water → Hydrogen + Metal Hydroxide Na(s) + 2H2O(l) H2(g) + NaOH(aq) metal hydroxide Ca(s) + 2H2O(l) H2(g) + Ca(OH)2(aq) metal hydroxide 42  Metal + Water → Hydrogen + Metal Oxide Fe(s) + 4H2O(g) 4H2(g) + Fe3O4(s) metal oxide 43  The Activity Series Metals An atom of an element in the K Ca activity series will displace an Na atom of an element below it Mg from one of its compounds. Al increasing Zn Fe Sodium (Na) will displace an activity Ni atom below it from one of its Sn compounds. Pb H Cu Ag Hg 44  Examples Metal Activity Series Metal Higher in Activity Series Displacing Metal Below It Mg(s) + PbS(s) MgS(s) + Pb(s) Metals Mg Al Zn Fe Magnesium is above lead Ni in the activity series. Sn Pb 45 Metal Lower in Activity Cannot Displace Metal Above It Ag(s) + CuCl2(s) no reaction Metals Pb H Cu Silver is below copper in Ag the activity series. Hg 46  Double Displacement Reactions The Tworeaction compoundscan be exchange thoughtpartners of as anwith exchange each A B displaces D C and combines with D C other of to positive produce and two negative differentgroups. compounds. AB + CD AD + BC 47 The Following Accompany Double Displacement Reactions formation of a precipitate release of gas bubbles release of heat formation of water 48  Examples Acid Base Neutralization acid + base → salt + water HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l) H2SO4(aq) + 2NaOH(aq) Na2SO(aq) + 2H2O(l) 49  Formation of an Insoluble Precipitate AgNO3(aq) + NaCl(aq) AgCl(s) + NaNO3(aq) Pb(NO3)2(aq) + 2KI(aq) PbI2(s) + 2KNO3(aq) 50  Metal Oxide + Acid metal oxide + acid → salt + water CuO(s) + 2HNO3(aq) Cu(NO3)2(aq) + H2O(l) CaO(s) + 2HCl(aq) CaCl2(s) + H2O(l) 51  Formation of a Gas H2SO4(aq) + 2NaCN(aq) Na2SO4(aq) + 2HCN(g) NH4Cl(aq) + NaOH(aq) NaCl(aq) + NH4OH(aq) indirect gas formation NH4OH(aq) NH3(g) + H2O(l) 52 Any Question  Contact Details Dr. Mostafa Ghasemi Associate Professor Faculty of Engineering Email: [email protected] Course Moderator Dr. Amal Alsaadi Assistant Professor Chemical Engineering Faculty of Engineering Email:[email protected] 54  ‫شكرا‬ ً Thank You 55