STM 006 General Chemistry 2 PDF

**INTERMOLECULAR FORCES OF ATTRACTION** Module 2 **INTRAMOLECULAR FORCES** Forces exist between two **atoms.** Example: Water (H2O) - the bond between Hydrogen and Oxygen. **2 TYPES OF INTRAMOLECULAR FORCES** 1\. Ionic Bond-metal and non-metals 2\. Covalent Bond-non-metals **2 types of Cova...

**INTERMOLECULAR FORCES OF ATTRACTION** Module 2 **INTRAMOLECULAR FORCES** Forces exist between two **atoms.** Example: Water (H2O) - the bond between Hydrogen and Oxygen. **2 TYPES OF INTRAMOLECULAR FORCES** 1\. Ionic Bond-metal and non-metals 2\. Covalent Bond-non-metals **2 types of Covalent Bonds** 1\. Polar Bond 2\. Non-Polar Bond **INTERMOLECULAR FORCES** \- forces exist between **molecules** -much more weaker than intramolecular forces. - determines the physical properties (boiling point, enthalpies, vaporization, and density)  **KINETIC MODEL OF MOLECULES** Module 3 **KINETIC PARTICLE THEORY** - The kinetic particle theory is a scientific idea that helps us understand how particles behave in different states of matter. - According to the kinetic particle theory, particles are always moving. The speed of their movement depends on the state of matter they are in. **PROPERTIES OF SOLIDS** **Definite Shape** - Solids have a definite shape, meaning that they maintain their shape and size unless acted upon by an external force. **Definite Volume** - Solids have a definite volume, which means that they occupy a fixed amount of space. This property is related to their density, which is the mass per units, **High Density** - Solids are usually denser than liquids and gases. This is because the particles that make up solids are closely packed together, and they have little room to move around. **Rigidity** - Solids are rigid and maintain their shape even when subjected to external forces. This property is due to the strong forces of attraction between the particles in a solid. **PARTICLES OF SOLID** Tightly Packed - The particles in a solid are tightly packed together and have little space between them. Regular Pattern - The particles in a solid are arranged in a regular pattern, forming a fixed shape. Strong Attraction - The particles in a solid have strong attractive forces between them, which keep them in their fixed positions and maintain its shape and volume. **PROPERTIES OF LIQUID** **Indefinite Shape** - Liquids do not have a fixed shape and take the shape of their container, allowing them to be poured or transferred. **Definite Volume** - Liquids have a fixed volume, meaning they cannot be easily compressed or expanded, and take up space. **High Density** - Liquids have a relatively high density compared to gases, meaning they are more massive per unit of volume. **Flowability** - Liquids are able to flow and be poured due to the mobility of their particles, which can slide and move past each other. **PARTICLES OF LIQUID** **Closely Packed** - The particles of liquids are closely packed, but not arranged in a regular pattern like in solids. **Attraction** - The attractive forces between liquid particles are weaker than in solids, but stronger than in gases. Kinetic Energy - The particles have more kinetic energy than solid particles, allowing them to move and slide past each other while remaining relatively close together. **PROPERTIES OF GASES** **Indefinite Shape** - Gases have no fixed shape because their particles are free to move and take on the shape of their container. **Indefinite Volume** - Gases have no fixed volume because their particles are free to move and fill the space available to them, regardless of the size of the container. **Low Density** - Gases have a low density because their particles are widely spaced, and there is a lot of empty space between **particles.** **High Diffusivity** - Gas particles can quickly diffuse throughout a container because of their high mobility and the lack of strong attractive forces between particles. **Widely Spaced** - Gas particles are widely spaced and have no definite shape or volume. **Fills Space** - Gas particles fill the space they occupy, regardless of the size or shape of the container. **Kinetic Energy** - Gas particles move rapidly in all directions with high kinetic energy. **Attraction** - Gas particles have little attraction to one another and can bounce off each other and the walls of their container**.** **Understanding** **Molecular Movement** Kinetic Theory Explained **Translation Motion** - The movement of particles or molecules from one point to another within the same axis is known as translation motion.  **Rotational Motion** - It is the movement of particles around the axis. - one of the best examples of this type of motion is seen in solid-state. **PHYSICAL CHANGES AND PARTICLE MOTION** **PHASE CHANGES IN MATTER** - Phase changes in matter is the process by which matter changes from one physical state or phase to another. The three most common phases of matter are **solid, liquid, and gas.** **LET\'S TALK ABOUT LATENT HEAT** - Latent heat is the amount of heat energy that is absorbed or released by a substance during a phase change, such as when a solid melts into a liquid or a liquid vaporizes into a gas. - Melting is a process in which a solid substance changes into a liquid state due to an increase in temperature. - When a solid is heated, the kinetic energy of its molecules increases, causing the molecules to vibrate and move more rapidly. - Once these bonds are broken, the molecules become less tightly packed, and they are able to move around more freely, which causes the solid to turn into a liquid. **BOILING** - Boiling is a process in which a liquid substance changes into a gas state due to an increase in temperature and pressure. - When a liquid substance is heated, the energy that is added to it causes the molecules to move around more rapidly and collide with each other more frequently. - As the temperature and pressure increase, this process continues until all of the liquid has been converted into gas. **EVAPORATION** - Evaporation is a process in which a liquid substance changes into a gas state at a temperature below its boiling point, due to the energy supplied to the surface molecules of the liquid. - When a liquid is exposed to air, the -- more energetic molecules near the surface of - the liquid can escape into the air as gas molecules. This process continues until all of the liquid has been converted into gas. **SUBLIMATION** - Sublimation is a process in which a solid substance changes directly into a gas state without first becoming a liquid. - This can occur either through the addition of heat, or the reduction of pressure, or both. - Sublimation process of dry ice - Sublimation occurs when the temperature and pressure are such that the solid can\'t undergo melting and instead goes directly into the gas phase. **FREEZING** - Freezing is a phase change in which a liquid substance changes into a solid state. - This occurs when the temperature of a liquid is lowered below its freezing point, at which point the molecules become strong enough to hold them in a fixed position relative to each other. - The freezing point of a substance depends on factors such as pressure and the presence of impurities. **CONDENSATION** - Condensation is a phase change in which a gas substance changes into a liquid state. - This occurs when the temperature of a gas is lowered below its dew point, at which point the molecules become strong enough to cause them to come closer together and form a liquid. - Condensation is a common occurrence in nature and can be seen in different phenomena. **DEPOSITION** - Deposition is a phase change in which a gas substance changes into a solid state without first passing through the liquid state. - This occurs when the temperature of a gas is lowered below its sublimation point, at which point the molecules become strong enough to cause them to come closer together and form a solid. - This can result in the formation of frost, snowflakes, or other types of ice crystals. **Liquids and the Intermolecular Forces of Attraction** - Liquids are fluids. Many of the liquid's properties can be associated with the intermolecular forces that exist between the molecules. These properties vary noticeably among various liquids. **A.) Viscosity**- The tendency of a liquid to resist flow. In general, the stronger the intermolecular forces of attraction, the more viscous the liquid is. **B.) Surface Tension**- It is a measure of the inward forces that must be overcome to expand the surface area of a liquid. **C.) Capillary Action**- All forces holding a liquid together are called cohesive forces. The forces of attraction between a liquid and another surface are adhesive forces. **D.) Vapor Pressure**- The partial pressure of vapor molecules above the surface of a liquid at equilibrium at a given temperature is the vapor pressure (vp) of the liquid at that temperature. **Solids and the Kinetic Molecular Theory of Matter** - Solids may be classified as to either amorphous solids or crystalline solids. Crystalline solids such as ice and sodium chloride have well-defined, sharp melting temperatures. The shattering of a crystalline solid can produce fragments having the same (or related) interfacial angles and structural characteristics as the original sample. - Some non-crystalline solids, called amorphous solids, have no well-defined, ordered structure. Particles in amorphous solids are irregularly arranged, so intermolecular forces among their particles vary in strength within a sample. **COMPARISON OF CONCENTRATION UNITS** STM 006 \| MODULE 5 **CONCENTRATIONS OF SOLUTIONS** - In a solution, the solute is distributed evenly throughout the solvent. This means that any part of a solution has the same ratio of solute to solvent as any other part of the solution. **a). Percent by mass (% m/m)** **b). Percent by Volume (% v/v)** **c. )Mole Fraction (X)** **d). Molarity (M)** **e). Molality (m)** **f). Parts Per Million (ppm)** A. PERCENT BY MASS  SAMPLE: What is the percent by mass of 5.00 g of iron (II) sulfate dissolved in 75.0 g of water? **Step 1: Identify the given** **mass of solute** = 5.00 g FeSO4 **mass of solvent** = 75.0 g H2O **mass of solution** is equal to mass of **solute+ mass of solvent** = 80.0 g **Find: % by mass** **Step 2: Use the formula to answer the problem** B. **PERCENT BY VOLUME**  - A solution is made by adding 25.0 mL of benzene to 80.0 mL of toluene. What is the percent by volume of benzene? **Step 1: Identify the given** **volume of solute** = 25.0 mL benzene **volume of solvent** = 80.0 mL toluene **volume of solution** is equal to volume of **solute+ volume of solvent** = 105 mL Find: % by volume **Step 2: Use the formula to answer the problem** C. **MOLE FRACTION** - Mole Fraction is computed by dividing the number of moles of one component (either the solute or solvent) with the total number of moles of the solution. Remember that mole fraction is dimensionless, meaning, it has no units!  **EXAMPLE:** A solution is prepared by mixing 100.0 g of water, H2O, and 100.0 g of ethanol, C2H5OH. Determine the mole fractions of each substance. **Step 1: Identify the given** **mass of H2O**= 100.0 g **mass of C2H5OH** = 100.0 g **Find**: mole ratios of water and ethanol **Hint**: Use the molar masses of the given to convert the masses to moles **Step 2: Use the formula to answer the problem** **Moles of the solution= 5.549 mol + 2.171 mol =7.720**  TIP: The sum of the mole ratios of the components should be equal to 1! D. **MOLARITY (M)** - Molarity is the number of moles of solute dissolved in the volume of solution in Liters---that is:  **EXAMPLE:** What is the molarity of a potassium chloride solution that has a volume of 400.0 mL and contains 85.0 g KCl? **Step 1: Identify the given** volume of solution = 400.0 mL mass of solute = 85.0 g KCl Find: molarity of KCl solution = ? **Step 2: Use the formula to answer the problem** E. **MOLALITY (e)** - Molality is the number of moles of solute dissolved in mass of solvent in kilograms that is:  **EXAMPLE:** Calculate the molality of a sulfuric acid solution containing 24.4 g of sulfuric acid in 198 g of water. The molar mass of sulfuric acid is 98.09 g. **Step 1: Identify the given** **Mass of solute**: 24.4 g H2SO4 **Mass of solvent**: 198 g H2O **Mass of solution**: 24.4 g + 198 g : 222.4 **Molar mass of H2SO4** : 98.98g/mol **Find**: molality **Step 2: Use the formula to answer the problem** F. **PARTS PER MILLION (PPM)** - Parts per million is computed by dividing the mass of solute in grams with the mass of the solution in grams and multiplying it with 106 or 1 000 000. It is oftentimes are used for solutions where the concentration of solutes are extremely small. EXAMPLE: - Find the concentration in ppm of a solution in which 0.55 g of NaCl has been dissolved making a solution with a mass of 750 g. **Step 1: Identify the given** Mass of solute: 0.55 g NaCl Mass of the solution: 750 g NaCl solution Find: ppm of the solution **Step 2: Use the formula to answer the problem**