Units 2 - 3 Matter, Energy, and Changes

Matter & Changes

Matter Is anything that has mass and volume

Matter States: Gas – no definite shape or volume, particles randomly scattered (high entropy), particles moving quickly in constant motion, highly compressible, low density, rapid diffusion, high expansion on heating

Matter States: Liquid – no set shape, definite volume, particles somewhat organized, particles free to move, slightly compressible, high density, slow diffusion, low expansion on heating

Properties of Liquids Viscosity – friction or resistance to motion, increases as temperature decreases Surface tension – molecules at the surface experience imbalanced attractive forces

Matter States: Solid – has particular shape, definite volume, particles very organized and close together (low entropy), particles move only very slightly, low compressibility, high density, slow diffusion, low expansion on heating

Basic Types of Solids Crystalline solids – are made of atoms arranged in highly ordered, repeated patterns called unit cells Amorphous solids - appear solid, but are more of a super-cooled liquid, have high viscosity, gradually soften as temperature increases

Properties of Solids Some solids are good conductors due to particles being in contact with each other and passing the energy from one to another

Matter State of matter at room temperature depends on strength of intermolecular forces For example, a substance with strong IM forces will be a solid while a substance with very weak IM forces will be a gas

Matter Intermolecular Forces Are the forces between neighboring molecules

Matter Intermolecular Forces: Dispersion forces Attraction between 2 induced dipoles

Matter Intermolecular Forces: Dipole-dipole forces Attraction between 2 permanent dipoles

Matter Intermolecular Forces: Hydrogen “bond”: Attraction between a partially positive H on one molecule and a partially negative atom on another molecule

Matter Properties: Physical – density, color, melting point (can be observed w/o altering substance) Chemical – flammability, reactivity (must alter to observe)

Matter Changes: Physical – matter is not altered, particles stay in same arrangement (includes change of state) Chemical – identity of substance is altered, particles are rearranged

Matter Law of Conservation of matter: matter is neither created nor destroyed in any process

Elements, compounds & mixtures Element – substance that cannot be separated into simpler substances by chemical change, organized in Periodic Table

Elements, compounds & mixtures Element – substance that cannot be separated into simpler substances by chemical change, organized in Periodic Table Compound – 2 or more elements combined by chemical change

Elements, compounds & mixtures Pure Substance or Mixture Pure Substance – has unique set of chemical & physical properties (includes all elements and compounds)

Elements, compounds & mixtures Pure Substance or Mixture Pure Substance – has unique set of chem & phys properties (includes all elements and compounds) Mixture – blend of 2 or more substances (not combined chemically)

Elements, compounds & mixtures Pure Substance or Mixture Pure Substance – has unique set of chem & phys properties (includes all elements and compounds) Mixture – blend of 2 or more substances (not combined chemically) Types: Heterogeneous – visibly different parts Homogeneous – no visibly different parts

Elements, compounds & mixtures Mixture Separation Filtration – often used for heterogeneous mixes

Elements, compounds & mixtures Mixture Separation Filtration – often used for heterogeneous mixes (not homogeneous) Distillation – heat liquid & drive it off, leaving solid (or liquid w/ higher boiling point)

Elements, compounds & mixtures Mixture Separation Filtration – often used for heterogeneous mixes Distillation – heat liquid & drive it off, leaving solid (or liquid w/ higher boiling point) Crystallization – evaporate liquid, leaving solid

Elements, compounds & mixtures Mixture Separation Filtration – often used for heterogeneous mixes Distillation – heat liquid & drive it off, leaving solid (or liquid w/ higher boiling point) Crystallization – evaporate liquid, leaving solid Chromatography – flow solution along stationary source

Energy & Temperature

Energy Energy is the capacity to do work or produce heat.

Energy Forms: Radiant ex. sunlight

Energy Forms: Radiant – ex. sunlight Kinetic energy carried by objects in motion (includes mechanical & thermal)

Energy Forms: Potential Radiant – ex. sunlight Kinetic – energy carried by objects in motion (includes mechanical & thermal) Potential due to position/stored energy (includes electrical & chemical)

Energy Measuring: calories (cal) – amount of heat needed to raise temperature of 1 g H2O by 1 C 1 cal = 1 g × 1 C Food energy is in Calories, 1 Cal = 1 kcal

Energy Measuring: SI unit is Joule (J) calories (cal) – amount of heat needed to raise temperature of 1 g H2O by 1 C 1 cal = 1 g * 1 C Food energy is in Calories, 1 Cal = 1 kcal SI unit is Joule (J)

Energy Measuring: SI unit is Joule (J), 1 J is about the energy to lift a medium-sized apple 1 meter from ground 1 cal = 4.184 J

Energy Law of Conservation of Energy: in any process, energy is neither created nor destroyed

Temperature What is temperature? comparison of how hot or cold an object is with some standard measure of the average kinetic energy of the particles in a sample of matter

Temperature Units for Temperature Fahrenheit Celsius Kelvin (SI units)

Temperature Units for Temperature Kelvin (SI units) Fahrenheit Celsius Kelvin (SI units) Why don’t we use a degree mark with Kelvin temperatures? What is the lowest Kelvin temperature? Why do we call it absolute zero?

Temperature Units for Temperature A quick look at the three scales. 0 C = 273 K = 32 F 100 C = 373 K = 212 F

Temperature Converting Fahrenheit/Celsius C = 5/9 × (F – 32)

Temperature Convert 98.6 F to C Convert 25 C to F

Temperature Converting Kelvin/Celsius C = K – 273

Temperature Convert 399 K to C Convert 25 C to K.

Changes of State

Changes of State Energy and change of state… To change states, particles must overcome the attractive forces holding them together (the number of particles does not change)

Changes of State Vaporization Liquid changes to a gas, also called evaporation, requires energy input

Changes of State Vaporization Liquid changes to a gas, also called evaporation, requires energy input Rapidly moving particle near surface of liquid gains enough energy to escape attractive forces of other particles

Volatile liquid – one that readily evaporates Changes of State Vaporization Liquid changes to a gas, also called evaporation, requires energy input Rapidly moving particle near surface of liquid gains enough energy to escape attractive forces of other particles Volatile liquid – one that readily evaporates

Changes of State Boiling point Temperature at which vapor pressure becomes equal to the atmospheric pressure

Changes of State Heat of vaporization Amount of heat necessary to vaporize a given amount of liquid

Changes of State Heat of vaporization You have 18.2 moles of water. How much energy is needed to vaporize the sample? (Molar heat of vaporization for water = 40.7 kJ/mole)

Changes of State Condensation Gas changes to a liquid, releases energy

Changes of State Freezing (Solidification) Particles get closer together and more organized than in the liquid state, releases energy

Changes of State Melting (Liquefying) Particles become less organized and farther apart, requires energy input

Changes of State Melting Melting point - temperature at which solid and liquid form of substance exist in equilibrium, also called freezing point

Changes of State Melting Heat of fusion - amount of heat needed to convert a given amount of solid into a liquid

Changes of State Melting You have a 278 mole block of ice. How much energy is needed to melt it? (Molar heat of fusion for water = 6.00 kJ/mole)

Changes of State Sublimation Solid changes directly to a gas, requires energy input

Changes of State Deposition Gas changes directly to a solid, releases energy

Changes of State Heating curves Describe changes of state of matter, plot of sample temperature as a function of time

Changes of State

Changes of State Phase diagrams Relates states of matter to temperature and pressure

Changes of State