Balancing, Molar Mass, % Composition, Scientific Notation Unit 4 – Part 1

What is a Chemical reaction Chemical Reactions Substances change into new substances   How Do You Know A Chemical Reaction Has Occurred? Gives off heat (feels hot) or absorbs heat (feels cold) Give off light Produces a gas (it bubbles) Forms a precipitate (2 liquids mix and a solid forms) Changes color

What is a Chemical reaction General Stuff about Chemical Reactions Can be written in words or symbols Always obeys Law of Conservation of Mass – matter cannot be created or destroyed Reactants – ingredients – left side o f arrow Products – cookies – right side of arrow

How to Balance a Chemical Reaction Always start with good formulas Must have equal numbers of each atoms on left and right side of arrow Can NEVER CHANGE the subscripts You can only change COEFFICIENTS

How to Balance a Chemical Reaction _____P + _____H2 → _____P4H10 _____PbO2 → _____PbO + _____ O2 ___Zn(OH)2 + ___H3PO4 → ___Zn3(PO4)2 + ___H2O

How to Balance a Chemical Reaction ____NaCl + ____H2SO4 → ____Na2SO4 + ____HCl ____H2 + ____ Fe3O4 → ____ Fe + ____ H20