Notes (Day 4) Matter and Change

Chemistry is… …the study of the composition, structure, and properties of matter and the changes it undergoes C 2 H 5 OH + 3 O 2  2 CO H 2 O + Energy Reactants  Products Chemical changes result in the formation of new substances. This ethanol burner produces new substances and heat.

Matter Can it be separated by physical means? Yes No MixturePure Substance Is the composition the same throughout? Homogeneous Mixture Solutions (soda) Stainless steel Sugar in water Heterogeneous Mixture Granite Wood Blood YesNo Can it be broken down by ordinary chemical means? Compound H 2 O (water) NaCl (Salt) CO 2 (carbon dioxide) Element Gold, Au Silver, Ag Copper, Cu Carbon, C YesNo

Atom The smallest unit of an element that maintains the properties of that element Element A pure substance made of only one kind of atom. The simplest form of matter that keeps its properties.

Compound A substance that is made from the atoms of two or more elements that are chemically bonded. Sucrose – C 12 H 22 O 11 Sucrose is also known as table sugar.

Representing states of matter in a chemical equation Solid LiquidGasAqueous (dissolved in water) Ice H 2 O (s) Liquid water H 2 O (l) Steam H 2 O (g) Salt water NaCl (aq)

3 H 2 SO 4 (aq) Coefficient Chemical Symbols SubscriptsPhase notation

Properties of Matter Physical properties: Physical state (solid, liquid, gaseous) Solubility (Ability to dissolve in water) Properties that DO NOT change the identity of the substance. Color (The banana is yellow) Odor (The substance smells rotten) Phase change (Melting point & boiling point) Other examples:

Properties of Matter Chemical properties Ability to form a NEW SUBSTANCE. Combustible or Flammable (Starts on FIRE) Explosive Corrosive (Weaken and destroy) Toxic (Poisonous) Color changes (The yellow banana turned brown)

Properties of Matter Physical properties: Chemical properties Properties that DO NOT change the identity of the substance. Ability to form a NEW SUBSTANCE.

Mixtures Physical combination of two or more substances that does NOT result in a chemical reaction. Homogeneous Mixture Soda Ink  Uniform composition.  This means the mixture is the “Same” throughout.  Example: Mountain dew.

Mixtures Physical combination of two or more substances that does NOT result in a chemical reaction. Heterogeneous Mixture Vegetable soup Concrete  Non uniform composition.  “Different” throughout.  Example: Muddy water.

Acid Rain Gases like CO 2 can react with water vapor in the air to make acid rain. Word Equation Carbon dioxide + Water  Carbonic acid Chemical Equation CO 2 (g) +  H 2 CO 3 (aq) H 2 O (g) (a weak acid) George Washington: BEFORE George Washington: AFTER Effects of Acid Rain on Marble (calcium carbonate)

Basic definition: Acids:Produce hydrogen ions, H +, when dissolved in water. Bases:Produce hydroxide ions, OH -, when dissolved in water.

Acid-Base Neutralization Acid+ Base  Water+Salt HCl+ NaOH  +NaClH2OH2O H+H+ OH -

Acids Have a pH less than 7 Rain water is acidic

Acid Rain Gases like CO 2 can react with water vapor in the air to make acid rain. Carbon dioxide + Water  Carbonic acid CO 2 (g) +  H 2 CO 3 (aq) H 2 O (g) Additional gases that make acid rain: (strong acids) SO 2 (g) NO 2 (g) +  H 2 SO 4 (aq) H 2 O (g) +  HNO 3 (aq) H 2 O (g) (a weak acid) Note: these equations are not balanced From burning coal From vehicle emissions Sulfuric acid (used in car batteries) Nitric acid