Chemical Equations Part I

Chemical Change One or more substances are converted into different substances. 2/19/2019 HFinks '07

Chemical Reaction One or more substances are converted into different substances. represented with chemical equations 2/19/2019 HFinks '07

Indicators of a Chemical Reaction Evolution of heat and light 2/19/2019 HFinks '07

Indicators of a Chemical Reaction Production of a gas 2/19/2019 HFinks '07

Indicators of a Chemical Reaction Formation of a precipitate 2/19/2019 HFinks '07

Indicators of a Chemical Reaction Color Change 2/19/2019 HFinks '07

Halogen Displacement Colour change Yes Yes No Yes No No KBr added KI added KI added Bromine water KCl added Chlorine water Iodine water KBr added KCl added 2/19/2019 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. 2/19/2019 HFinks '07

Chemical Equations Use symbols and formulas to represent the identities and relative amounts of the reactants and products in a chemical reaction. 2/19/2019 HFinks '07

Chemical Equations: Symbols → = yields (results of reaction) (s) = solid (ℓ) = liquid (g) = gas (aq) = aqueous (dissolved in water) 2/19/2019 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. 2/19/2019 HFinks '07

Symbols ↔ or →← = reaction is reversible products re-form the original reactants 2/19/2019 HFinks '07

Chemical Equations: Idenities Word Equation: reactants and products in a chemical reaction are represented by words. carbon + oxygen yields carbon dioxide 2/19/2019 HFinks '07

Chemical Equation: Identities Formula Equation: reactants and products in a chemical reaction are represented by symbols or formulas C + O2 → CO2 2/19/2019 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 2/19/2019 HFinks '07

Reactants & Products Mg(s) + 2HCl(aq) → MgCl2(aq) + H2 (g) Reactants: magnesium metal hydrochloric acid Products: magnesium chloride hydrogen gas 2/19/2019 HFinks '07

Simple Chemical Reactions Synthesis Decomposition Single Replacement Double Replacement Combustion 2/19/2019 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 2/19/2019 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 2/19/2019 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 2/19/2019 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 2/19/2019 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 2/19/2019 HFinks '07

Classifying Chemical Reactions Classify the equations on the next five slides as either Synthesis Decomposition Single Replacement Double Replacement Combustion 2/19/2019 HFinks '07

Equation 1 2NaI + F2 (g) → 2NaF + I2(g) 2/19/2019 HFinks '07

Equation 2 N2(g) + 3H2(g) → 2NH3(g) 2/19/2019 HFinks '07

Equation 3 C2H6 + 5O2(g) → 3H2O(g) + 2CO2(g) 2/19/2019 HFinks '07

Equation 4 2AgCl(aq)+BaBr2(aq) → 2AgBr(aq)+ BaCl2(aq) 2/19/2019 HFinks '07

Equation 5 2H2O(ℓ) → 2H2(g) + O2(g) 2/19/2019 HFinks '07

Classifying Reactions Answers 2/19/2019 HFinks '07

Single Replacement Equation 2NaI + F2(g) → 2NaF + I2(g) One ion, fluorine (F), exchanged places with iodine (I) in NaI. 2/19/2019 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. 2/19/2019 HFinks '07

Combustion Reaction Equation 3 C2H6 + 5O2(g) → 3H2O(g) + 2CO2(g) C2H6, ethane, burned in oxygen produced water and carbon dioxide 2/19/2019 HFinks '07

Double Replacement Reaction Equation 4 2AgCl(aq) + BaBr2(aq) → 2AgBr(aq)+ BaCl2(aq) Two ions, chloride (Cl-) and bromide (Br-) exchanged partners. 2/19/2019 HFinks '07

Decomposition Reaction Equation 5 2H2O(ℓ) → 2H2(g) + O2(g) Water, H2O broke up into hydrogen gas, H2, and oxygen gas, O2. 2/19/2019 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 2/19/2019 HFinks '07