Presentation on theme: "Chapter 8.1: Describing Chemical reactions"— Presentation transcript:
1 Chapter 8.1: Describing Chemical reactions What I know about chemical reactions and conservation of matter?
2 WaterHow many different ways can you alter the water “physically” and still end up with water?List the ways you could alter the water “chemically” to create a new substance that is no longer the same as the original substance?
3 Sec 8-1: Chemical reaction evidenceHeatLightSoundElectricaltemperature changeenergyGasPrecipitateColorOdorforms
4 Also there are Physical change Melting pointsDensityCondensationEvaporationFreezing
5 Example:determine whether each of the following is a chemical or physical change. bending a toothpickburning a matchburning sugarmaking a cake from scratchsmashing a canmelting ice to water
6 How to represent Ch. R. Describe Equations chemical reactions Word equationhydrogen (a gas) + sulfur yields hydrogen sulfideFormula equationSymbols (C, Na, and Fe) elementsFormulas (NaOH) compoundsEquations chemical reactions
7 Equation Reactants (on the left) Products (on the right) separated by arrowincluded physical statesExamples:Iron + Oxygen Iron (III) oxideMethane + oxygen Carbon dioxide + water
8 Practice ProblemWhen solid aluminum oxide and hydrogen gas are heated, molten aluminum and water vapor form.a. Write a word equation for the above reaction.Aluminum oxide + hydrogen aluminum + waterb. Write an unbalanced formula equation using all appropriate symbols.
9 To write an unbalanced equation You mustWrite the correct formulas of the reactants and the products.Indicate physical state by putting a symbol after each formula.Indicate catalyst by writing its formula above arrow.Indicate heat and any change above arrow.Practice Problem: Write an unbalanced equation below word equation.Methane + oxygen Carbon dioxide + water