HONORS CHEMISTRY UNIT TWO MATTER : States, Changes, Mixtures & Solutions Matter Matter – anything that has a mass and takes up space. Law of Conservation of Mass/Matter - Matter cannot be created or destroyed in a chemical reaction but only rearranged to form different substances PROPERTIES CHEMICAL PHYSICAL INTENSIVE EXTENSIVE Part A: Characteristics of Matter Physical Properties - characteristics that can be observed without the production of a new substance. Examples: color, smell, taste, hardness, density, texture, melting/boiling/freezing points, magnetic attraction, solubility, electrical conductivity, temperature, state or phase Types of physical properties: Extensive: depends on how much there is Examples: volume, mass, weight, etc Intensive: depends on the type of matter (not the amount) Examples: density, melting/boiling pts, color (sometimes) Part A: Characteristics of Matter Chemical Properties - describes how a substance reacts or fails to react with other substances to produce new substances Examples: oxidation, corrosion, hydrolysis, combustion, flammability, reaction to acid or base. Part B: Kinetic Theory & Energy Kinetic Theory - all matter is made of tiny particles (atoms and molecules) that are in constant motion Potential Energy (PE) - energy due to position or condition At the atomic level it refers to the distance between particles Closer = lower PE Farther = higher PE Kinetic Energy (KE) – energy of motion Faster = higher KE Slower = lower KE Part C: States of Matter State or Phase Particle level picture Particles Description Keep Volume? Solid Arranged in orderly pattern Yes Liquid Touching, but not tightly packed No Far apart and rarely touching No No Gas Yes Keep Shape? Yes Part C: States of Matter State or Phase Particle Movement Solid Vibrational only Low Low Ice Liquid Vibrational & translational Moderate Moderate Water Gas Move freely High Vapor Amount PE Amount KE High Example Plasma - 4th state of matter (extraordinary), consists of electrically charged, high energy particles Examples: fluorescent lights, stars, lightning, lasers PART C: CHANGE IN MATTER Types of Changes Physical Change – an alteration of a substance that only changes the physical properties of a substance * Does not change the chemical composition! Chemical Change – an alteration of the chemical composition of a substance that results in the formation of a new substance. Always forms a new substance with new physical and chemical properties Also known as a chemical reaction Temperature change, color change, formation of a precipitate, formation of a gas, and odor change Matter Pure Substances Elements Compounds Mixtures Homogeneous Heterogeneous Part D: Classification of Matter Pure Substance - made of only one type of matter Element - made of only one type of atom cannot be changed into simpler substances under normal ordinary conditions Compound - atoms of two or more elements, chemically combined in a definite ratio. Mixture – a physical combination of two or more substances no definite ratio of particles Homogeneous mixture - atoms of two or more elements, physically combined in no definite ratio. - The same throughout. - Must be a SOLUTION Heterogeneous mixture - two or more types of atoms, physically combined in no definite ratio. -Different throughout Part D: Classification of Matter - Types of mixtures: 1. 2. 3. Solution – Particles are Very tiny, will not separate by filtering, will not settle out when allowed to stand, particles too small to scatter light, (-) Tyndall effect. Ex. Kool Aid, brine Colloid – Particles are tiny, will not separate by filtering, will not settle out when allowed to stand, particles will scatter light, (+) Tyndall effect. Ex. Milk, whipped cream, aerosols Suspension – Particles visible with unaided eye, will separate when filtered, will settle out if allowed to stand, particles will scatter light, (+) Tyndall effect. Ex. Muddy water, snow globe - Homogeneous mixture Solution a solute dissolved in a solvent The solvent is the part in greater quantity (usually water) solute solvent - Homogeneous mixture Solution Example: salt water - Homogeneous mixture Solution Electrolyte – a solution that conducts electricity in water Example: salt water Non-example: sugar water - Homogeneous mixture Solution Soluble – able to dissolve Salt dissolves in water (opposites attract) Water is a polar molecule and a universal solvent Dipole – dipole forces: attraction between oppositely charged regions of polar molecules “Like dissolves like” – polar dissolves polar (salt & water), non-polar dissolves non-polar (oil in gasoline) - Homogeneous mixture Solution 1) The solution is well stirred during formation. 2) Particles will not settle out 3) It is clear and transparent 4) Considered to be in one phase and will not filter unless extremely fine filter paper is used Types of solutions 1) Gas-Gas - Carbon dioxide, Nitrogen, Oxygen (air) 2) Liquid-Gas - Water Vapor in Air (moist air) 3) Gas-Liquid - Carbon dioxide in Water (soda water) 4) Liquid-Liquid - Acetic acid in Water (vinegar) 5) Solid-Liquid - Sodium chloride in Water (brine or salt water) 6) Solid-Solid - Copper in Silver (Sterling Silver) Part E: The Mole Atomic Mass A single atom has a very small mass (on the order of 10-23 grams per atom) Because this mass is so small, we use a unit called amu to describe the mass of a single atom (for example, 1 atom of carbon has a mass of 12.011 amu) Average atomic mass - the weighted average of the masses of all isotopes of an element atomic mass units are not practical for use in the lab (too small a quantity) grams are the preferred unit of mass Therefore, scientists needed a way to determine the number of atoms in a given mass of an element The Mole Carbon-12 was selected as the standard. The number of atoms in 12.0 g of C-12 was determined experimentally using sophisticated equipment The number came out to be 6.022 x 1023 this number is called a mole (mol) The amount of a pure substance that contains 6.022 x 1023 particles of that substance Try it this way… There are 6.022 x 1023 carbon atoms in 12 grams of carbon There are 6.022 x 1023 hydrogen atoms in 1.0 grams of hydrogen There are 6.022 x 1023 oxygen atoms in 16.0 grams of oxygen There are 6.022 x 1023 gold atoms in 197 grams of gold The Mole (cont.) The mole establishes a relationship between the atomic mass unit and the gram. The mole is used to describe a huge amount of any extremely small particle. A mole of gold, a mole of salt and a mole of water each contain 6.022 x 1023 individual units. How would you feel about inheriting a mole of pennies??? $6.02 x 1021 or $6,020,000,000,000,000,000,000 If you gave $1million a day to every person on Earth, it would take you > 3000 yrs to run out of money Calculating Molar Mass The mass in grams of 1 mole of a substance. Example: H2O H 2 x 1.01 = 2.02 g O 1 x 16.00 = 16.00 g 18.02 g The molar mass of H2O = 18.02 g/mol Keep two digits after the decimal for molar mass! Converting Moles Grams How many grams are in 3.6 moles of NaCl? 3.6 moles NaCl x = Converting from Grams Moles How many moles are in 1.75 g of BeF2? 1.75 g BeF2 x = Part F: Concentration of Solutions Molarity (M) – The number of moles of solute dissolved in each liter of solution Molarity = moles of solute liters of solution Problems: What is the molarity when 0.75 mol is dissolved in 2.50 L of solution? If you had 75.0 g of NaCl and you dissolved it in exactly 2.00 L of solution. What would be the molarity of the solution? Part F: Concentration of Solutions Problems: If you wanted to make a 3.0 L of 4.0 M HCl solution. How much HCl would you need in grams? Part G: Solution Solubility Solution Solubility - the amount of solute that dissolves in a given quantity of solvent at a given temperature to produce a saturated solution Expressed in g/100 g solvent Solution concentrations: Saturated solution – Contains the maximum amount of solute for a given amount of solvent at a constant temperature. Unsaturated solution - Contains less solute than a saturated solution. Supersaturated solution – Contains more solute than is should be able to hold at a given temperature. (Unstable) Factors that affect solubility: Nature, temperature and pressure, amount of solute already dissolved - Homogeneous mixture Solution Increase solubility by… Stir the solution – increase of collisions and the breaking of solute attraction Decrease the particles size of the solute – increases surface area, smaller particles – more area for contact with the solvent Increase temperature – in crease the temperature of the solvent increases kinetic energy and the number of collisions between particles - Homogeneous mixture o Solubility curve - Homogeneous mixture Solubility curve questions 1) Generally, what happens to the solubility of a substance as its temperature rises? 2) A solution is made by dissolving 40 g in 100 g of water at 80°C. What is the substance? 3) How many grams of this substance would be required to make a 100 g solution at 20°C? 4) A solution is made with 120 g of NaNO3 at 70°C. Is this solution saturated, unsaturated or supersaturated? 5) What happens to a solution of NaNO3 when it is cooled from 80°C to 60°C? 6) What mass of NaNO3 is needed to make a saturated solution at 20°C with 250 g of water?