Presentation on theme: "Chapter 8.1: Describing Chemical reactions"— Presentation transcript:
1Chapter 8.1: Describing Chemical reactions What I know about chemical reactions and conservation of matter?
2WaterHow 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?
3Sec 8-1: Chemical reaction evidenceHeatLightSoundElectricaltemperature changeenergyGasPrecipitateColorOdorforms
4Also there are Physical change Melting pointsDensityCondensationEvaporationFreezing
5Example: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
6How 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
7Equation Reactants (on the left) Products (on the right) separated by arrowincluded physical statesExamples:Iron + Oxygen Iron (III) oxideMethane + oxygen Carbon dioxide + water
8Practice 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.
9To 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