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Learn about chemical change, equations, properties, and types of reactions. Explore indicators like color change, gas production, and more. Watch videos for visual examples.
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Chemical Equations Part I
Chemical Change One or more substances are converted into different substances. HFinks '07
Chemical Reaction One or more substances are converted into different substances. represented with chemical equations HFinks '07
Indicators of a Chemical Reaction • Evolution of heat and light HFinks '07
Indicators of a Chemical Reaction • Production of a gas HFinks '07
Indicators of a Chemical Reaction • Formation of a precipitate HFinks '07
Indicators of a Chemical Reaction Color Change HFinks '07
Halogen Displacement KBr added KI added KI added Bromine water KCl added Chlorine water Iodine water KBr added KCl added HFinks '07 Colour change Yes Yes No Yes No No
Chemical Property Ability of a substance to undergo a change that transforms it into a different substance. HFinks '07
Chemical Equations Use symbols and formulas to represent the identities and relative amounts of the reactants and products in a chemical reaction. HFinks '07
Chemical Equations: Symbols • → = yields (results of reaction) • (s) = solid • (ℓ) = liquid • (g) = gas • (aq) = aqueous (dissolved in water) HFinks '07
Symbols ↓ = precipitate = can be used in place of (s) ↑ = gaseous state can be used in place of (g) • A precipitate is a solid that is produced as a result of a chemical reaction in solution and that separates from the solution. HFinks '07
Symbols ↔ or →← = reaction is reversible products re-form the original reactants HFinks '07
Chemical Equations: Idenities Word Equation: reactants and products in a chemical reaction are represented by words. carbon + oxygen yields carbon dioxide HFinks '07
Chemical Equation: Identities Formula Equation: reactants and products in a chemical reaction are represented by symbols or formulas C + O2 → CO2 HFinks '07
Two Main Parts • Reactants – substance(s) that combine chemically in a chemical reaction. • Products – substance(s) formed by a chemical change. • Example: Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) Reactants Products HFinks '07
Reactants & Products Mg(s) + 2HCl(aq) → MgCl2(aq) + H2 (g) Reactants Products Reactants: magnesium metal hydrochloric acid Products: magnesium chloride hydrogen gas HFinks '07
Simple Chemical Reactions • Synthesis • Decomposition • Single Replacement • Double Replacement • Combustion HFinks '07
Synthesis Two or more substances combine to form a new compound. Example: 2C(s) + O2 (g) → 2CO(g) Carbon + oxygen gas produces carbon monoxide HFinks '07
Decomposition A single compound produces two or more simpler substances. Example ∆ 2HgO(s) → 2Hg(ℓ) + O2(g) heated mercury (II) oxide produces liquid mercury and oxygen gas HFinks '07
Single Replacement One element replaces a similar element in a compound. Example Mg(s) + 2HCl(aq) → MgCl2(aq) + H2 (g) Magnesium metal plus hydrochloric acid produces magnesium chloride in solution and hydrogen gas HFinks '07
Double Replacement Ions of two compounds exchange places in an aqueous solution to form two new compounds. Example FeS(s) + 2HCl(aq) → H2S(g) + FeCl2(aq) Solid iron (II) sulfide plus hydrochloric acid yields hydrogen sulfide gas plus iron (II) chloride HFinks '07
Combustion A substance combines with oxygen, releasing a large amount of energy in the form of light and heat. Example 2H2(g) + O2(g) → 2H2O(g) Hydrogen gas burned in the oxygen produces water HFinks '07
Classifying Chemical Reactions Classify the equations on the next five slides as either • Synthesis • Decomposition • Single Replacement • Double Replacement • Combustion HFinks '07
Equation 1 2NaI + F2(g) → 2NaF + I2(g) HFinks '07
Equation 2 N2(g) + 3H2(g) → 2NH3(g) HFinks '07
Equation 3 C2H6 + 5O2(g) → 3H2O(g) + 2CO2(g) HFinks '07
Equation 4 2AgCl(aq)+BaBr2(aq) → 2AgBr(aq)+ BaCl2(aq) HFinks '07
Equation 5 2H2O(ℓ) → 2H2(g) + O2(g) HFinks '07
Classifying Reactions Answers HFinks '07
Single Replacement Equation Equation 1 2NaI + F2(g) → 2NaF + I2(g) One ion, fluorine (F), exchanged places with iodine (I) in NaI. HFinks '07
Synthesis Reaction Equation 2 N2(g) + 3H2(g) → 2NH3(g) Nitrogen, N2, combined with hydrogen, H2, to form ammonia Nitrogen and hydrogen are diatomic when written ALONE. HFinks '07
Combustion Reaction Equation 3 C2H6 + 5O2(g) → 3H2O(g) + 2CO2(g) C2H6, ethane, burned in oxygen produced water and carbon dioxide HFinks '07
Double Replacement Reaction Equation 4 2AgCl(aq) + BaBr2(aq) → 2AgBr(aq)+ BaCl2(aq) Two ions, chloride (Cl-) and bromide (Br-) exchanged partners. HFinks '07
Decomposition Reaction Equation 5 2H2O(ℓ) → 2H2(g) + O2(g) Water, H2O broke up into hydrogen gas, H2, and oxygen gas, O2. HFinks '07
Videos of Chemical Reactions Copy and paste the urls below to see examples of reactions. 1. Synthesis http://www.cci.ethz.ch/mainmov.html?expnum=26&ismovie=0&picnum=-1&control=0&language=1&exchap=2+-1&exlist=-1 2. Single Replacement : http://www.cci.ethz.ch/mainmov.html?expnum=113&ismovie=0&picnum=-1&control=0&language=1&exchap=3+-1&exlist=-1 3. Double Replacement: http://www.cci.ethz.ch/mainmov.html?expnum=143&ismovie=0&picnum=-1&control=0&language=1&exchap=3+-1&exlist=-1 4. Decomposition: http://www.cci.ethz.ch/mainmov.html?expnum=178&ismovie=0&picnum=-1&control=0&language=1&exchap=12+-1&exlist=-1 5. Combustion: http://www.cci.ethz.ch/experiments/Zigarre/en/stat.html HFinks '07