Presentation on theme: "DESCRIBE PHYSICAL & CHEMICAL CHANGES IN TERMS OF ENDOTHERMIC & EXOTHERMIC PROCESSES COS 5.0."— Presentation transcript:
DESCRIBE PHYSICAL & CHEMICAL CHANGES IN TERMS OF ENDOTHERMIC & EXOTHERMIC PROCESSES COS 5.0
WHAT YOULL LEARN Explain the relationship between, matter atoms & elements Categorize materials as pure substances or mixtures Identify elements & compounds Perform calculations involving density Compare & Contrast physical & chemical properties Determine how the law of conservation of mass applies to chemical changes Compare & Contrast physical & chemical changes Describe how to detect whether a chemical change has taken place. Describe the four common states of matter. List the different changes of state & describe how particles behave in each state Describe differences between endothermic & exothermic reactions
COMPOSITION MATTER anything that has mass and takes up space (volume) ATOMS smallest particle of an element that has same properties of element MOLECULES smallest unit of a substance that keeps all of physical and chemical properties of that substance. Two or more atoms that are chemically bonded
PURE SUBSTANCE sample of matter, either a single element or a single compound, that has definite chemical and physical propertiessample of matter, either a single element or a single compound, that has definite chemical and physical properties
ELEMENTS substance that cannot be separated or broken down into simpler substances by chemical means Can be found as solids, liquids, or gases Found on periodic table Made of identical atoms Pure substances Represented by abbreviations/symbols consisting of one or two letters Examples: H, N, S, O, P, Au, Hg, Na
COMPOUNDS substance made of atoms of two or more different elements that are chemically combined they always combine in same proportions. Can be broken down through chemical means Pure substances Every compound is different from the elements it contains.
CHEMICAL FORMULAS combo of chemical symbols and numbers to represent a substance. Subscript represents number of atoms located lower right of chemical symbol Examples: NO 2, NH 3, NaCl, C 6 H 6 O 6
MIXTURES two or more substances that are NOT chemically combined. Variable composition Each components retains their characteristic properties May be separated into pure substances by physical methods classified by how thoroughly the substances mix. Two types
HOMOGENEOUS may be pure substances or solutions Pure substances may be compounds or elements substances are evenly distributed well mixed Look/have the same composition throughout Particles are small and not easily recognized can be separated by physical means (dissolution, centrifuge, gravimetric filtering, etc.). Examples: milk, yogurt
HETEROGENEOUS made of more than one kind of substance. substances arent mixed uniformly least mixed different particles in mixtures are large enough to be seen easily separated by physical means (ie. density, polarity, metallic properties).
Matter Flowchart MATTER Can it be separated by physical means? Homogeneous Mixture (solution) Heterogeneous MixtureCompoundElement MIXTUREPURE SUBSTANCE yesno Can it be decomposed by chemical means? noyes Is the composition uniform? noyes
PROPERTIES OF MATTER
PHYSICAL PROPERTIES characteristic of matter that can be directly observed without changing identity of substancecharacteristic of matter that can be directly observed without changing identity of substance you can see, such as color, shape, hardness, and textureyou can see, such as color, shape, hardness, and texture easily measuredeasily measured
MASS amount of matter in an object SI Unit: G r a m s (g)
WEIGHT measure of pull of gravity on an object SI Unit: N e w t o n s (N) Formula: W = m g
VOLUME amount of space taken up by an object. SI Unit: L i t e r s (L).
DENSITY mass per unit of volume Formula: Density = mass/volume
D = MVMV D M V
Density 1.An object has a volume of 825 cm 3 and a density of 13.6 g/cm 3. Find its mass. GIVEN: V = 825 cm 3 D = 13.6 g/cm 3 M = ? WORK : M = DV M = (13.6 g/cm 3 )(825cm 3 ) M = 11,220 g D M V
Density 2. A liquid has a density of 0.87 g/mL. What volume is occupied by 25 g of the liquid? GIVEN: D = 0.87 g/mL V = ? M = 25 g D M V WORK : V = M D V = 25 g 0.87 g/mL V = 28.7 mL
Density 3. You have a sample with a mass of 620 g & a volume of 753 cm 3. Find density. GIVEN: M = 620 g V = 753 cm 3 D = ? D M V WORK : D = M V D = 620 g 753 cm 3 D = 0.82 g/cm 3
Lets Try Some More Density Problems
Density 1. If the mass of a rock is 500 g and its volume is 25 cm 3, what is its density? GIVEN: M = 500 g V = 25 cm 3 D = ? D M V WORK : D = M V D = 500 g 25 cm 3 D = 20 g/cm 3
Density 2. If the density of a liquid is 1.2 g/ml and its volume is 10 ml, what is its mass? GIVEN: V = 10 ml D = 1.2 g/ml M = ? WORK : M = DV M = (1.2 g/ml)(10 ml) M = 12 g D M V
Density 3. If Bobs mass is 80 kg and his density is 1.6 kg/l, what is his volume? GIVEN: D = 1.6 kg/l V = ? M = 80 kg D M V WORK : V = M D V = 80 kg 1.6 kg/l V = 50 mL
BOILING POINT temperature and pressure at which a liquid becomes a gas liquid is still the same substance
MELTING POINT temperature and pressure at which a solid becomes a liquid
VISCOSITY resistance (difficulty) of a liquid to flow easily How thick or thin a liquid is high viscosity: Honey, motor oil, corn syrup low viscosity: water, milk, soda
CONDUCTIVITY ability to conduct heat or an electric current High conductivity: metals (copper, aluminum…) Low conductivity: wood, rubber, plastic
MALLEABILE Ability to be hammered into a thin sheet. Ability to be hammered into a thin sheet.
DUCTILE Ability to be drawn into a thin wireAbility to be drawn into a thin wire
CHEMICAL PROPERTIES describes how a substance can change or react to form new substances.describes how a substance can change or react to form new substances.
FLAMMABILITY ability of a substance to react in presence of oxygen and burn when exposed to a flame
REACTIVITY how easily a chemical reacts with other substances.
CHANGES OF MATTER
LAW OF CONSERVATION OF MATTER matter cannot be created nor destroyed. It is just converted from one form to another
STATES OF MATTER
SOLIDS Have a definite shape Have a definite shape Have a definite volume Have a definite volume Least amount of movement of particles. Least amount of movement of particles. Particles arranged in a regular pattern and tightly packed. Particles arranged in a regular pattern and tightly packed.
LIQUIDS Have an indefinite shape Have a definite volume will assume the shape of its container. Particles are close together but move about freely.
GASES Have an indefinite shape Have an indefinite volume Can fill any container
PLASMA most common form of matter. makes up over 99% of the visible universe dangerous, very high energy (found in stars)
ENDOTHERMIC/EXOTHERMIC REACTIONS Endothermic = heat energy is absorbed, cools surroundings Exothermic = heat energy is released, warms surroundings
PHYSICAL CHANGES substance changes state but does not change its chemical composition. Type of matter remains the same example: water freezing into ice, cutting a piece of wood into smaller pieces
DISSOLVING to disintegrate, break up, or disperse When a substance dissolves, the molecules of the substance do not change. Ways of Dissolving: solid in a liquid, gas in a liquid liquid in a liquid
MELTING to become altered from a solid to a liquid state usually by heat endothermic ice cubes melting
BOILING Change of a substance from a liquid to a gas. endothermic two types: –Boiling: rapid gas bubbles are produced throughout –Evaporation slow occurs at the surface is a cooling process ocean water evaporates to form clouds & rain droplets
CONDENSATION Change of a gas to a liquid. exothermic water vapor turns into dew
SUBLIMATION Changing directly from solid to gas or gas to solid skipping the liquid state. endothermic formation of frost/snow & dry ice
FREEZING Changing from a liquid to a solid. Particles lose kinetic energy and slow down. exothermic water turns to ice
CHEMICAL CHANGES change of a substance into a new and different substance aka chemical reaction cannot be reversed by physical changes. impossible to unbake a cake.
CHEMICAL REACTIONS Reactants: are the substances that enter a chemical reaction Products: are the substances formed by a chemical reaction
CHARACTERISTICS & EXAMPLES OF CHEMICAL CHANGES Reaction with acids Digestion, fizzing Reaction with oxygen (combustion) Explosions, Burning Ability to act as oxidizing agent Rusting Reaction with other elements production of heat, sound, light Decomposition into simpler substances change of smell, Decomposing Corrosion ---- water lines becoming thin Change in color -----Baking food Production of a gas Fermentation