Gen-Chem-1-6-prelims PDF

CHEMISTRY divided by the square of distance of separation ( ) MODULE 1: Intermolecular Forces and Liquids and Solids The PHYSICAL PRO...

CHEMISTRY divided by the square of distance of separation ( ) MODULE 1: Intermolecular Forces and Liquids and Solids The PHYSICAL PROPERTY such as MELTING POINT is greatly affected by the LESSON 1: Types of Intermolecular Forces (IMF) MAGNITUDE of lattice energy or The interaction between MOLECULES are electrostatic energy built between the ions governed by physical forces called The HIGHER the ELECTROSTATIC FORCE INTERMOLECULAR FORCES between molecules, the HIGHER the MELTING POINT Forces that arise from the way in how electrons are SHARED within COVALENT BONDS of EXAMPLE: ALUMINUM NITRIDE vs different molecules MAGNESIUM OXIDE Affects the PHYSICAL PROPERTIES of compounds 1. ION- ION INTERACTION ION - Charged particles or have permanent whole number charges 2. ION- DIPOLE INTERACTION LIKE CHARGES “REPEL”, and OPPOSITE CHARGES “ATTRACT” EXAMPLE: Pouring water molecules around The ATTRACTION between these ions are pulled sodium ions when dissolving sodium together by a force called ELECTROSTATIC chloride in water FORCE The ATTRACTION between these ions are pulled together by a force called ELECTROSTATIC FORCE  COULOMB’S LAW Electrostatic force is DIRECTLY WATER is a permanent DIPOLE molecule PROPORTIONAL to the CHARGE of IONS, because it has POSITIVE and NEGATIVE and INVERSELY PROPORTIONAL to the POLES as a result of uneven distribution of DISTANCE between them electrons within it When a molecule has TWO OPPOSITE POLAR CHARGES, they are DIPOLE and POLAR 3. DIPOLE - DIPOLE INTERACTION The STRENGTH of ELECTROSTATIC FORCE  DIPOLE- DIPOLE depends on the product of charges (Z1Z2)  Interaction of two dipole molecules wherein 5. LONDON DISPERSION INTERACTION the two poles of each molecule is either “van der Waals Intermolecular Forces” partially positive or partially negative Present in all types of molecules whether ionic or covalent- polar or nonpolar Significant in NON POLAR MOLECULES and the force is developed due to uneven distribution of electrons and create a TEMPORARY (INSTANTANEOUS) DIPOLE A very weak type of dipole interaction FLUORINE is MORE ELECTRONEGATIVE than NITROGEN The FORCE between molecules INCREASES with POLARIZABILITY (squishiness of Once a molecule of NITROGEN FLUORIDE molecule), MOLECULAR SIZE (more IONS reacts with another molecule of electrons), and pi bonding (overlapping of nitrogen fluoride, the PARTIAL NEGATIVE orbitals) FLUORIDE IONS will be attracted to PARTIAL POSITIVELY CHARGED NITROGEN of another nitrogen trifluoride molecule 4. HYDROGEN BOND INTERACTION It is responsible for the LIQUID PHASE of NOBLE GASES A special kind of DIPOLE- DIPOLE INTERACTION that occurs specifically between a HYDROGEN ATOM bonded to either an OXYGEN, NITROGEN, or FLUORINE ATOM The STRENGTH of HYDROGEN BONDING is relatively strong that requires ENERGY to break it This attraction between opposite charges is the COULOMB’S LAW, thus creating HIGH BOILING POINT and MELTING POINT TEMPORARY DIPOLE Also plays a vital role in holding the Arrangement of STRENGTH of FORCE present NUCLEOTIDE BASES in DNA and RNA among types of IMF (Strongest to weakest) The STRENGTH of HYDROGEN BONDING depends on the EXTENSIVENESS or NUMBER OF FORMED HYDROGEN BONDS and POLARITY OF BOND H-O < H- N < H-F (because H-F is a HIGHLY POLAR MOLECULE) STRONG INTERMOLECULAR FORCES increase the Particles that are arranged in crystal lattice physical behavior of molecules such as MELTING (repeating unit of crystalline solid and will POINTS, BOILING POINTS, VISCOSITY, AND SURFACE change sharply once heated AREA Classified as: LESSON 2: Properties of Liquids and Solids IONIC CRYSTAL- crystals made of metals and PROPERTIES OF LIQUIDS AND SOLIDS non metals; good conductor of heat once they are in SOLID STATE (ex: NaCl)  KINETIC MOLECULAR THEORY (KMT) COVALENT NETWORK CRYSTAL- has A model that is used to explain the behavior of extremely high melting point (Ex: quartz states of matter from the microscopic point of and diamond) view Help us explain why matter exists in different COVALENT MOLECULAR CRYSTAL- Contain phases (solid, liquid, gas) and how matter can two or more non metals like CH4, NH3, and change from one phase to the next H2O  KMT and PROPERTIES OF LIQUID 2. AMORPHOUS SOLID  Can FLOW Solid that lack the well- defined  Assume the shape of container arrangement of basic units found in crystals that soften gradually when heated  Molecules are close together with very little space, making them MORE DIFFICULT to EFFECT OF IMF TO SOME PHYSICAL PROPERTIES COMPRESS than gases 1. SURFACE TENSION  DENSER than gases under normal SURFACE TENSION is the amount of energy conditions required to stretch the surface of liquid by  Have definite volume unit area  “LIQUID has attractive forces that DO NOT A liquid molecule with HIGH IMF will have a BREAK the molecules away, influencing HIGH SURFACE TENSION some of its physical properties” 2. CAPILLARY ACTION  KMT and PROPERTIES OF SOLID CAPILLARY ACTION/ CAPILLARITY is the  Rigid and resistant to change attraction between liquid and solid materials  Particles is tightly arranged and organized TWO TYPES:  Highly dense and incompressible 1. COHESION- Intermolecular attraction  Definite shape, volume, and melting point between the same molecules  Low rate of diffusion 2. ADHESION- intermolecular attraction  TYPES OF SOLIDS between unlike molecules 1. CRYSTALLINE SOLID 3. VISCOSITY VISCOSITY is the resistance of liquid to flow  For a water molecule to vaporize 1 mole of a liquid at 100 degrees Celsius, this require an energy called MOLAR HEAT OF VAPORIZATION GLYCEROL has the HIGHEST IMF because of Substance ∆Hvap (kJ/ Boiling point the more build- up hydrogen bond mol) (degree C) “If molecule has HIGH IMF, the MORE Acetone 30.3 56.6 VISCOUS it is” (CH3COCH3) Ethanol 39.3 78.3 LIQUIDS VISCOSITY (Ns/ m2) (C2H5OH) Acetone (C3H6O) 3.16 X 10−4 Water (H2O) 40.79 100 Ethanol (C2H5OH) 1.20 X 10−3 “If molecule has HIGH BOILING POINT, the interaction between molecules is STRONG” Water (H2O) 1.01 X 10−3 LESSON 3: Properties of Water Glycerol (C3H8O3) 1.49 Water is one of our major necessities to “a liquid that has a LONG CHAIN of survive HYDROCARBON has the GREATER IMF” Water can also be destructive Water is well- known as UNIVERSAL SOLVENT Substance Formula PROPERTIES OF WATER Hexane CH3CH2CH2CH2CH2CH3 An inorganic compound that is colorless, odorless, tasteless, and considered as the Decane CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3 most important compound in the body 4. VAPOR PRESSURE “Universal solvent” (capability to dissolve more substances) Pressure created by bouncing molecules MAIN PROPERTIES: “a molecule that has a STRONG IMF would - Polarity give a LOW VAPOR PRESSURE” - Cohesion 5. MOLAR HEAT OF VAPORIZATION (∆Hvap) - Adhesion  BOILING POINT - Surface tension Temperature at which liquid converts into gas - Higher specific heat Temperature where vapor pressure of liquid equals external pressure (at equilibrium point)   MOLECULAR STRUCTURE OF WATER Solid water 2.11 Water molecule with ONE OXYGEN ATOM is (ice) COVALENTLY BONDED with TWO HYDROGEN ATOMS Water vapor 2.00 SHARING of electrons is not shared equally within molecules making water “POLAR” Dry air 1.01  INTERMOLECULAR FORCES OF WATER Basalt 0.84 Because of unequal sharing of electrons, this makes the OXYGEN side to be PARTIALLY NEGATIVE and HYDROGEN is Granite 0.79 PARTIALLY POSITIVE The bond that holds each WATER iron 0.45 MOLECULE is “HYDROGEN BOND” HYDROGEN BOND makes WATER “POLAR” Copper 0.38 and why water is “UNIVERSAL SOLVENT” Substances that are POLAR and READY to be lead 0.13 dissolved in water are called HYDROPHILIC (WATER- LOVING) Substances that are NONPOLAR which don’t  DENSITY OF LIQUID WATER VS. DENSITY OF dissolve in water are called HYDROPHOBIC ICE CUBE (WATER- FEARING) Solid form of water is LESS DENSE than its  WATER HAS HIGH SPECIFIC HEAT liquid form To raise the TEMPERATURE of WATER, we need an amount of ENERGY to BREAK the HYDROGEN BONDS of WATER “SPECIFIC HEAT” (the amount of heat needed to raise the temperature of 1 gram of substance 1 degree Celsius) As the temperature of water raises only slight, water has to absorb 4,184 Joules of heat (1 calorie) for the temperature of 1 kg of water to increase 1 degree Celsius “ANOMALOUS EXPANSION OF WATER”  WATER HAS HIGH SPECIFIC HEAT SPECIFIC HEAT OF SOME COMMON MATERIALS Material Specific Heat (Joule/ Gram degree Celsius) Liquid water 4.18   SURFACE TENSION, HEAT OF given solid at its melting point, converting VAPORIZATION, and VAPOR PRESSURE solid crystal into a liquid) WATER has the HIGHEST COHESION of any PROPERTIES OF CRYSTALLINE SOLID non- metallic liquid that results in HIGH 1. UNIT CELL SURFACE TENSION - Basic repeating structural unit of crystalline solids WATER’S SURFACE TENSION is due to HYDROGEN BONDING in water molecules - LATTICE POINT (spheres representing atoms or molecules which is identically arranged) The property of having HIGH COHESION made evident in the presence of DROPLETS - SHAPES OF CRYSTALLINE STRUCTURE on the surface of leaves or some paper wax where water beads up ADHESION, where water quite like to stick to (Example: water in the beaker) The adhesive force of water and glass is STRONGER than cohesive force between water molecules Water’s VAPOR PRESSURE is INVERSELY - PLANE OF SYMMETRY RELATED to its IMF Water has VERY STRONG IMF, then it has LOW VAPOR PRESSURE Water has HIGH HEAT OF VAPORIZATION which is 41 kJ/mol Water changes to gas (endothermic reaction) 2. STABLE CRYSTAL STRUCTURE DUE TO IMF - Has well- defined ordered structure in three dimensions, fixed by net attractive IMF LESSON 4: Structure of Crystalline and Amorphous Solids - Ionic forces, covalent bonds, LDF, Hydrogen forces, or combination of these help the STABILITY of CLASSES OF SOLIDS crystals  CRYSTALLINE SOLIDS - Structure and properties of crystals (Melting point, Composed of huge number of small crystals density, and hardness) are determined by IMF that with DEFINITE geometrical shape that hold the particles together makes them RIGID and INCOMPRESSIBLE - When these forces are BROKEN, these crystals Considered “TRUE SOLIDS” because of become LIQUID at specific temperature sharp melting points that once they reach TYPES OF CRYSTALS this point, they will immediately change into LIQUID FORM 1. IONIC CRYSTALS They also have “DEFINITE” HEAT OF FUSION (Amount of heat absorbed by unit mass of - Composed of charged particles where exact - Poor electrical conductors in solid and arrangement of ions in lattice varies according to molten state SIZE of ions in crystals 4. COVALENT CRYSTALS - ELECTROSTATIC INTERACTION is STRONG - Atoms are bonded covalently - “hard solids” - Strong IMF is present - Solid- state and molten state crystals are poor - Very high Melting point electrical conductors - Poor conductor of electricity - MELTING POINTS are HIGH - Can be made of one type of atom or different - BRITTLE once DEFORMED causing attractive forces atoms to be broken - EXAMPLES: Diamond, graphite, silicone carbide - EXAMPLE: Salt (NaCl) and quartz 2. METALLIC CRYSTALS  AMORPHOUS SOLIDS Held together by electrostatic force Has a structure that lacks a well- defined shape between CATIONS and delocalized electrons or regular three dimensional arrangement of ELECTRONS are WEAKLY ATTACHED to metal atoms atoms, where they can freely room across the entire metal “pseudo- solids” (behave as CRYSTALLINE at Good conductor of electricity and heat certain temperatures) or “supercooled liquids” Particles can move freely through the (liquid that have a temperature lower than its crystals and causing the transfer of kinetic freezing point and has not solidified) energy GLASS is a versatile example of amorphous solid Dense High melting point EXAMPLES: Chalk, Gels, rubber, plastics, various - Lustrous (they easily absorb and emit light) polymers, wax, thin films - Malleable (atoms can roll over each other AMORPHOUS SILICON is a photovoltaic material into new positions without breaking responsible in converting sunlight into electrical metallic bond) energy - EXAMPLES: gold, aluminum, iron metals, and metallic alloys They do not have sharp melting points 3. MOLECULAR CRYSTALS Weaker IMF Lattice points are occupied by molecules Different amount of thermal energy are needed Attractive force present is London to overcome interactions Dispersion Force or Hydrogen Bond Tend to soften slowly over wide temperature Molecules are packed closely as their shape range and size allow EXAMPLE: Ice and dry ice - Has low melting point at temperatures LESSON 5: Phase Diagram of Water and Carbon below 100 degree C Dioxide - Soft and brittle PHASE CHANGES When energy is ADDED or REMOVED, “TRANSFORMATIONS” from one phase to another will occur EXAMPLE: Water  When heat is ADDED up, it makes the water molecules move FASTER until it reaches its boiling point  EVAPORATION (Liquid to gas)  When heat is REMOVED, water molecules stick together and form solid- ice  FREEZING (liquid to solid) When energy is ADDED or REMOVED, CRITICAL POINT corresponds to specific “TRANSFORMATIONS” from one phase to pressure and temperature above which fluid another will occur has both properties of liquid and vapor EXAMPLE: Water SUPERCRITICAL FLUID is everything beyond the critical point  ICE will MELT if heat energy (melting point) from warmer air is ABSORBED and enough CRITICAL TEMPERATURE is where substance to break apart the particles of ice water is impossible to liquify no matter how you increase or compress the substance  MELTING (solid to liquid) It help us easily identify and tell the state of  WATER VAPOR will CONDENSE if molecules substance at given temperature and in gas COOL DOWN, losing heat energy pressure  CONDENSATION (gas to liquid) EXAMPLE: intersection between 1.0 atm PHASE DIAGRAM (standard atmospheric pressure) and 0 degree Celsius (temperature) Graph that relates PRESSURE and TEMPERATURE to the state of matter PHASE DIAGRAM OF WATER Three sections (solid, liquid, and gas) TRIPLE POINT where all three phases of water can exist at equilibrium in 0.006 atm LINES (boundaries signifying the dynamic and 0.01°CAt 1 ATM, CARBON DIOXIDE equilibrium between two or three phases) “SUBLIMES” directly to GAS TRIPLE POINT is the point where at a certain FREEZING POINT and MELTING POINT (at a pressure and temperature at equilibrium, all point of 1.00 atm and 0°C three phases of substance co- exist Water will be in its BOILING POINT if TEMPERATURE is INCREASED up to 100°C at constant pressure 1 atm (ready to become a GAS)  SLOPE in the boundary between of solid and liquid states is on POSITIVE SLOPE SOLID CARBON DIOXIDE is DENSER than LIQUID CARBON DIOXIDE If TEMPERATURE is INCREASED, it will create LIQUID CARBON DIOXIDE LESSON 6: Heating and Cooling Curve of a Substance HEATING CURVE OF WATER SLOPE in the boundary between solid and liquid becomes NEGATIVE WATER exists in different phases: LIQUID, SOLID, and GAS FREEZING POINT and MELTING POINT (at a point of 1.00 atm and 0°C WATER is HEATED UP at constant rate, the TEMPERATURE changes which is shown in the Water will be in its BOILING POINT if heating curve of water TEMPERATURE is INCREASED up to 100°C at constant pressure 1 atm (ready to become a GAS) PHASE DIAGRAM OF CARBON DIOXIDE X- axis (heat) Y- axis (temperature) TWO MAIN OBSERVATIONS ON THE MEASURED CURVE: 1. Region where the temperature increases as heat At 1 ATM, CARBON DIOXIDE “SUBLIMES” is added directly to GAS 2. Plateaus where temperature stay constant At a constant pressure of 1 ATM as TEMPERATURE “increases” from - 78°C, we can see SOLID and GAS states not in LIQUID PHASES TRIPLE POINT could be seen at 1 ATM and temperature of - 57°C  FIVE IMPORTANT PARTS OF HEATING CURVE: TEMPERATURE is constant PLATEAU is seen LIQUID- VAPOR EQUILIBRIUM (as the number of vapor increases, these vapor got strikes once again in water surface, captured, and turned into LIQUID PHASE) Water at POINT D shows all water has become GASEOUS WATER at 1 atm, 100 DEGREE CELSIUS HEAT OF VAPORIZATION (to calculate how much 1. The SOLID ICE is HEATED until the TEMPERATURE heat is absorbed) reached ZERO DEGREE CELSUIS where a FREEZING POINT or MELTING POINT is reached at POINT A TEMPERATURE continue to INCREASE 2. The MELTING PERIOD happens in segment A → B where the temperature is held constant COOLING CURVE OF WATER 3. The temperature of liquid RISES in segment B → C 4. The temperature will become constant again in segment C → D 5. At point D, all liquid water has become GASEOUS WATER at 1 atm and 100 degree Celsius Solid ice is heated until the temperature reaches Starts with GASEOUS PHASE and cools off until it hit zero degree Celsius where a FREEZING POINT or the POINT OF CONDENSATION MELTING POINT is reached at POINT A As it hits the POINT OF CONDENSATION, it The AMOUNT OF HEAT (q) can be computed using RELEASES the HEAT ENERGY, lowering the MOLAR HEAT OF FUSION (energy required to melt 1 TEMPERATURE mole of solid) As it reaches the POINT A, the VAPOR starts to MELTING POINT happens for second distinct part LIQUID WATER which is the CONDENSATION at 100 (A → B) in the heating curve of water degree Celsius The HEAT is being ABSORBED by the system The PLATEAU mean that the TEMPERATURE did TEMPERATURE is CONSTANT not drop wherein the HEAT OF VAPORIZATION take place The temperature of liquid begins to INCREASE as heat is absorbed by the system From point A → B, the mixture of vapor and liquid water is present Solid water has MELTED completely at segment B At point B, all the vapor is now CONDENSED into Temperature of liquid rises (B → C) water LIQUID begin to BOIL and reaches the Liquid water begins to drop and continue to temperature of BOILING POINT of water which is decrease as it releases more energy (EXOTHERMIC) 100 DEGREE CELSIUS until it reaches FREEZING POINT at point C  At Point C, liquid water begin to FREEZE and there is no temperature decrease occur HEAT OF FUSION take place between mixture of water liquid and ice water from point C → D Energy is released because water turned into ice In point D, all liquid water is converted into ICE