Chemical Equations Physical Change: -physical change is a change that merely changes the shape, volume, or phase of the substance (ie. gas, liquid, solid, plasma) ex: H2O (s), H2O (l), H2O (g) Nuclear Change: -nuclear change is a change in the nucleus which completely changes the elements involved -involves lots of energy Chemical Change: -chemical change is a change that fundamentally alters the composition of the substance ex: H2O2 can turn into H2 and O2

Chemical Equations -reactants: things to be combined together real life example: bread, meat, cheese -arrow: indicates what the reactants become or produces when they are put together -products: things that are made when the reaction is finished real life example: bread + meat + cheese  sandwich

Describe-An-Equation CH3COOH (aq) + NaHCO3 (s)  CO2 (g) + H2O (l) + NaCH3COO (aq) Using a descriptive paragraph, write down what is happening in the reaction above using the following words: gas liquid aqueous solid acetic acid (CH3COOH) sodium bicarbonate (NaHCO3) carbon dioxide (CO2) water (H2O) reacts produces sodium acetate (NaCH3COO)

Types of Reactions

Chemical Equations Types of Reactions -Decomposition reaction: one reactant is broken apart into two or more substances Ex: AB  A + B H2O2 (l)  H2O(g) + O2 (g) -Combination/Synthesis reaction: two or more substances combine to form a single product Ex: A + B  AB H2O (g) + O2 (g)  H2O2 (l)

Chemical Equations Types of Reactions -Single Exchange: starts with an element and a compound. The compound breaks apart and one piece combines with element while other piece is left in elemental form. Ex: AB + C  AC + B Cl2 + CaI2  CaCl2 + I2 Mg + 2HCl  MgCl2 + H2

Chemical Equations Types of Reactions -Double Exchange: starts with two compounds that break apart. The parts recombine into two new products. Ex: AB + CD  AD + CB CsF + NaOH  NaF + CsOH PbI2 + K2S  PbS + 2KI