Pharmaceutical Inorganic & Physical Chemistry Lecture Notes PDF

Pharmaceutical Inorganic & Physical Chemistry Dr. Mahmoud Mohamed Abbas Lecturer of Pharmaceutical Analytical Chemistry Faculty of Pharmacy, Galala University gu.edu.eg Compounds Molecules and compounds Compounds are formed by atoms bon...

Pharmaceutical Inorganic & Physical Chemistry Dr. Mahmoud Mohamed Abbas Lecturer of Pharmaceutical Analytical Chemistry Faculty of Pharmacy, Galala University gu.edu.eg Compounds Molecules and compounds Compounds are formed by atoms bonding together by either: - Covalent bonds-> Molecular compounds - Ionic bonds -> Ionic compounds or salts The molecule is the smallest unit of the compound holding its characteristic chemical properties. “A compound is made of different elements in definite proportions”. Types of compounds Ionic compounds - Products of reaction between acids and bases - The formed compound is known as salt. which is formed of cations and anions - Ionic compounds are formed as crystal structure with the cations and anions according to their ratios in the molecule. - They have high melting and boiling point, low or no vapor pressure, good electric conductivity of their solution in water.  Types of compounds Molecular compounds  Includes diatomic elements (H, N, O and Halogens) and non-metallic covalently bonded compounds e.g. H2O, NH3, CH4, C2H5OH  They have lower melting and boiling point.  They exist in gas, liquid and solid phase states.  They are easy to volatilize. Molecule representation Molecules are represented by the following methods: Molecular formula: Each element followed by its number of atoms in the molecule (written in sub- script) e.g. H2O, CO2, C4H8 Empirical formula: the simplest ratio of atoms in a compound. For example in butene C4H8, the empirical formula is CH2 Structural formula: Atoms connected by lines corresponding to bonds Atomic weight scale and molecular weight Atomic weight scale and Mole 12C atom was considered to contain 12 Atomic Mass Unit. 12 g of 12C was considered to represent 1 Mole of 12C 1 Mole of 12C contains 6.022×1023 of 12C atoms. This number is called Avogadro’s number Atomic weight scale and Mole Mole of an element: One mole of any element has a mass in grams equivalent to the atomic mass weight of this element. For example, 1 mole of sodium = 22.989 gm ≈ 23 gm One mole of any element contains Avogadro’s number of that element atoms. Atomic weight scale and Mole Mole of a compound (includes diatomic elements): - One mole of any compound with a molecular formula of AXBY has a mass in grams equivalent to the sum of mass weights of its atoms = (X × A atomic mass) + ( Y × B atomic mass) → (Molecular weight or relative molecular mass, Mr). - One mole of any compound has a mass in grams equivalent to its molecular weight - One mole of any compound contains Avogadro’s number of that compound molecules Molecular weight calculations - Write the chemical formula - Get the atomic mass for each element (from periodic table) - Multiply each element by the number of its atoms in molecule - Sum the masses of resulting products together. Express the resulting figure by gram → Molecular weight - Example: Water: H2O Mole= (2 × 1.008) + (1 × 15.999 )=18.015g Mole Calculations Calculate Mole of the following: - CO2 - CH4 - CH3OH Use the following atomic masses: C=12, H=1, O=16 Mole Calculations Calculate Mole of the following: CO2 (1×12)+(2×16) →44g CH4 (1×12)+(4×1)→16g CH3OH (1×12)+(4×1)+(1×16)→32g Use the following atomic masses: C=12, H=1, O=16 Writing salts chemical formulae Writing salts formulae We want to write the formula of the salt Barium Chloride. 1. Order the symbols of each element ion as Cation- Anion-assign charges to them Ba2+ Cl- 2. Under the cation at right, write the number of charges on the anion. 3. Under the anion at right, write the number of charges on the cation. Ba12+ Cl2- 4. Remove the charges over the ions and combine symbols together with their ratios of the numbers you had written down them. Delete number if =1. BaCl2 How to write salts (polyatomic anions-cations example) We want to write the formula of the salt Ammonium carbonate. 1. Order the symbols of each element ion as Cation-Anion- assign charges to them NH4+ CO32- 2. Under the cation at right, write the number of charges on the anion. 3. Under the anion at right, write the number of charges on the cation. 4. Use parenthesis if the written number >1 (NH4+)2 CO32- 1 5. Remove the charges over the ions and combine symbols together with their ratios of the numbers you had written down them. Delete number if =1. (NH4)2CO3 Try to write Sodium Chloride Aluminum sulfate Calcium carbonate Try to write Sodium Chloride Na+ Cl- -> Na1 Cl1 -> NaCl Aluminum sulfate Al3+ (SO4)2- -> Al2 (SO4)3 -> Al2(SO4)3 Calcium carbonate Ca2+ (CO3)2- -> Ca2 (CO3)2 -> Ca(CO3) -> CaCO3 Stocks system For metals with multiple oxidation number. Such as Iron: Fe2+ / Fe3+ (ferrous/ferric) A roman number is written after the name of metal to indicate the required oxidation number. For example : Ferric chloride = Iron (III) chloride= FeCl3 Ferrous chloride = Iron (II) chloride = FeCl2 Reactions and reaction types Types of reactions 1. Synthesis reactions 2. Decomposition reactions 3. Single displacement reactions 4. Double displacement reactions 5. Combustion reactions You need to be able to identify each type. Types of reactions 1. Synthesis reactions: When two compunds react together and form a new chemical compound. This may occure by breaking bonds in the reactants to form new bonds in the product compound. They could be also called “Combination reactions” Example C + O2 → CO2 General Equation: A + B → AB Synthesis reactions examples Types of reactions Practice on Synthesis reactions Predict the products then balance the equations. Na(s) + Cl2(g) → Answer 2Na(s) + Cl2(g) → 2NaCl Mg(s) + F2(g) → Answer Mg(s) + F2(g) →MgF2 Al(s) + F2(g) → Answer 2Al(s) + 3F2(g) → 2AlF3 Types of reactions 2. Decomposition reactions: The opposite of the synthesis reactions. Bonds of a compound are broken to produce two or more smaller compounds General Equation: AB → A + B Types of reactions 3. Single Displacement reactions A reaction in which one element is substituted for another element in a compound. General Equation: A + BC → AC + B Example: Zn + CuCl2 → ZnCl2 + Cu This reaction is common when a metal with more activity in the electrochemical series is allowed to react with the salt solution of a metal which is less active in the electrochemical series. The more active metal displaces the less active metal. Examples of Single displacement reactions Types of reactions Single displacement Reactions Questions: Write and balance the following equations: Zn(s) + HCl(aq) → Answer Zn(s) + 2 HCl(aq) → ZnCl2 + H2(g) NaCl(s) + F2(g) → Answer 2 NaCl(s) + F2(g) → 2NaF(s) + Cl2(g) Al(s)+ Cu(NO3)2(aq) → Answer 2Al(s)+ 3Cu(NO3)2(aq) → 3Cu(s)+ 2Al(NO3)3(aq) Types of reactions 4. Double displacement reactions: A type of chemical reaction in which two reactants exchange ions to form two new compounds. General equation: AB + CD → AD + CB Examples of double displacement reactions Types of reactions Practice on double displacement reactions Complete the equations with balancing them HCl (aq) + AgNO3 (aq) → Answer: HCl (aq) + AgNO3 (aq) → AgCl (s) ↓ + HNO3 (aq) Pb(NO3)2 (aq) + BaCl2 (aq) → Answer: Pb(NO3)2 (aq) + BaCl2 (aq) → Pb Cl2 (S) ↓ + Ba(NO3)2 (aq) FeCl3 (aq) + NaOH (aq) → Answer: FeCl3 (aq) + 3NaOH (aq) → 3NaCl (aq) + Fe(OH)3 (S) ↓ Types of reactions 5. Combustion Reactions A combustion reaction is an exothermic chemical reaction between substances, usually including oxygen gas and accompanied by the generation of heat and light (flame). This is also called burning!!! The products of a combustion reaction depend on the combusted substance: When metals and nonmetals burn in the presence of oxygen, they will give off their corresponding oxides. On the other hand, hydrocarbons give off carbon dioxide and water upon combustion. In order to burn something you need the 3 components of the “fire triangle”: 1) Fuel (hydrocarbon) 2) Oxygen 3) Something to ignite the reaction (spark) Thank You For any questions, feel free to contact me by email [email protected] gu.edu.eg