What Happened in Activity 3? Solid Aluminum was added to a solution of Copper (II) chloride Al(s) + CuCl2(aq) → ? Name a physical change that occurred??? How do you know it was a physical change??? Name a chemical change that occurred???? How do you know it was a chemical change??? Activity Series of Metals Decreasing Activity Li K Ba Sr Ca Na Mg Al Mn Zn Al(s) + CuCl2(aq) → AlCl3(aq) + Cu(s) Fe Cd Co Ni Sn Pb H Cu Ag Hg Au What do you see? Law of Conservation of Matter Matter can not be created or destroyed! Matter can only change forms! Physical change The material itself is the same before and after the change. The change can usually be “undone.” Ice melting: an example of a physical change. Physical Change You still have bronze! Melting bronze into a liquid Physical Change Ripping Paper But this one can’t be undone so easily. Origami The form/shape may change, but you still have paper Cracking an Egg Another example of an irreversible physical change. Beating an Egg Hammering Metal Malleability is a physical property of metals. Malleable: the ability to be hammered, pressed or rolled into thin sheets without breaking is a physical change. Ghost Crystals (crosslinked polyacrylamide) + water Physical change!! Given time the water will evaporate away and leave the crystals Sodium Polyacrylate Theses crystals are If left to dry long found in the "super enough, it would absorbent layer" in return to its original most disposable state or appearance. diapers. It can absorb 200 to 300 times its weight in tap water Physical Change Review 1. Only the state of matter changes 2. All Phase changes are physical changes (Solid---Liquid---Gas)! 3. NO new substances are formed! 4. Not all physical changes are reversible (crushing a rock). Chemical Change The substances present at the beginning of the change are not present at the end; new substances are formed. The change cannot be “undone.” A nail rusting: an example of chemical change. Raw Egg Fried Egg COOKING Chemical Change! The proteins in the egg have changed! The cooked egg cannot change back to a raw egg. Chemical Reaction! Your body chemically reacts with the food you eat to make nutrients and energy! Burning Chemical Change! Rust is a new substance! (color change) Car with rust = PHOTOSYNTHESIS 6 CO2 + 6 H2O → 6(CH2O) + 6 O2 sugar Evidence of a Chemical Change • Color Change • Bubbling (formation of a gas) • Light given off • Temperature change • Precipitate formed. Chemical Reaction! Formation of a Precipitate lead iodide (PbI2), forms from the mixture of two clear liquids, potassium iodide (KI) and lead nitrate (Pb(NO3)2). Chemical Change Review 1. A chemical reaction occurs 2. New substance(s) are formed with NEW properties 3. It can not be reversed! Macroscopic Definition Microscopic Definition Physical Change The matter is the same. The original matter can be recovered. The particles of the substance are broken apart, and the atoms are rearranged. Chemical Change The matter is different. The old matter is no longer present. The original matter cannot be recovered. The particles of the substance are broken apart, and the atoms are rearranged into new particles, forming a new substance. Physical vs. Chemical • Examples: – melting point physical – flammable chemical – density physical – magnetic physical – tarnishes in air chemical Yellow & Blue Switcheroo Yellow & Blue Switcheroo Oscillating Reaction Chemical! Color Change indicates the chemical properties of the indicator were changed! New product formed! Can’t be reversed! Pour a Rainbow Acids to a Base Reactions Color change & Polymerization A Chemical Change Occurs!! We have now made our own slime! Old Foamy Old Foamy Chemical Change Old Foamy Hydrogen Peroxide & Sodium Iodide Solution With Dishwashing Detergent New product formed! Can’t be reversed! Whoosh Bottle Chemical Change Exothermic Reaction: O2 + Combustion CO2 & H2O Color & Heat released New product formed! Can’t be reversed!