Presentation on theme: "Chapter 11: Chemical Reacitons"— Presentation transcript:
1 Chapter 11: Chemical Reacitons 11.1 Describing Chemical Reactions
2 Signs of a Chemical Reaction Color changeSolid forms (precipitate)Bubbles (gas) producedChange in temperature
3 Writing Chemical Equations 11.1Writing Chemical EquationsWord EquationsTo write a word equation, write the names of the reactants to the left of the arrow separated by plus signs; write the names of the products to the right of the arrow, also separated by plus signs.Reactant + Reactant Product + Product
4 Writing Chemical Equations 11.1Writing Chemical EquationsChemical EquationsA chemical equation is a representation of a chemical reaction; the formulas of the reactants (on the left) are connected by an arrow with the formulas of the products (on the right).
5 Writing Chemical Equations 11.1Writing Chemical EquationsA skeleton equation is a chemical equation that does not indicate the relative amounts of the reactants and products.Here is the equation for rusting:Fe + O2 Fe2O3
6 Writing Chemical Equations 11.1Writing Chemical EquationsA catalyst is a substance that speeds up the reaction but is not used up in the reaction.Without Catalyst With CatalystHydrogen peroxide decomposes to form water and oxygen gas. a) Bubbles of oxygen appear slowly as decomposition proceeds. b) With the addition of the catalyst manganese(IV) oxide (MnO2), decomposition speeds up. The white “smoke” is condensed water vapor.
7 Writing Chemical Equations 11.1Writing Chemical Equations
10 Balancing Chemical Equations 11.1Balancing Chemical EquationsTo write a balanced chemical equation, first write the skeleton equation. Then use coefficients to balance the equation so that it obeys the law of conservation of mass.
11 Balancing Chemical Equations 11.1Balancing Chemical EquationsThis is a balanced equation for making a bicycle. The numbers are called coefficients—small whole numbers that are placed in front of the formulas in an equation in order to balance it.
12 Balancing Chemical Equations 11.1Balancing Chemical EquationsA chemical reaction is also described by a balanced equation in which each side of the equation has the same number of atoms of each element and mass is conserved.
13 Helpful Tips Balance one element at a time. Update ALL atom counts after adding a coefficient.If an element appears more than once per side, balance it last.Balance polyatomic ions as single units.“1 SO4” instead of “1 S” and “4 O”
18 ExampleSolid calcium metal reacts with water to form aqueous calcium hydroxide and hydrogen gas.
19 ExampleHydrogen peroxide in an aqueous solution decomposes to produce oxygen and water
20 ExampleSolid copper metal reacts with aqueous silver nitrate to produce solid silver metal and aqueous copper (II) nitrate
21 Practice1) Solid mercury (II) oxide decomposes to produce liquid mercury metal and gaseous oxygen2) Solid carbon reacts with gaseous oxygen to form gaseous carbon dioxide
22 Practice3) Gaseous ammonia reacts with gaseous hydrogen chloride to form solid ammonium chloride4) Iron metal reacts with oxygen gas to form solid iron (II) oxide
23 Practice5) Solid magnesium reacts with liquid water to form solid magnesium hydroxide and hydrogen gas6) Gaseous ammonia reacts with gaseous oxygen to form gaseous nitrogen monoxide and gaseous water
24 Practice7) Nitrogen monoxide gas reacts with hydrogen gas to form nitrogen gas and water8) Lithium metal reacts with chlorine gas to form solid lithium chloride
25 11.1 Section Quiz.1.Propane gas reacts with oxygen to produce water vapor and carbon dioxide. Choose the correct word equation for this reaction.a) propane + carbon dioxide water + oxygenb) propane + oxygen + water carbon dioxidec) propane + oxygen + water + carbon dioxided) propane + oxygen water + carbon dioxide
26 11.1 Section Quiz. 2. Which of the following is a skeleton equation? a) H2 + CO CH3OHb) 2H2 + CO CH3OHc) 2H2 + CO2 CH3OHd) hydrogen + carbon monoxide methanol
27 11.1 Section Quiz.3. What coefficient for H2SO4 is required to balance the following equation?Ca3(PO4)2 + ____ H2SO4 3CaSO4 + 2H3PO4a) 1b) 2c) 3d) 4
29 Classifying Reactions 11.2Classifying ReactionsThe five general types of reaction are combination, decomposition, single-replacement, double-replacement, and combustion.
30 Classifying Reactions 11.2Classifying ReactionsA combination (synthesis) reaction is a chemical change in which two or more substances react to form a single new substance.When ignited, magnesium ribbon reacts with oxygen in the surrounding air to form magnesium oxide, a white solid. This is a combination reaction. Observing Why do you think this reaction was once used in flashbulbs for photography?
34 Classifying Reactions 11.2Classifying ReactionsA decomposition reaction is a chemical change in which a single compound breaks down into two or more simpler products.When orange-colored mercury(II) oxide is heated, it decomposes into its constituent elements: liquid mercury and gaseous oxygen. Comparing and Contrasting How are the two reactions pictured so far similar? How are they different?
38 Classifying Reactions 11.2Classifying ReactionsA single-replacement reaction is a chemical change in which one element replaces a second element in a compound.The alkali metal potassium displaces hydrogen from water and forms a solution of potassium hydroxide in a single-replacement reaction. The heat of the reaction is often sufficient to ignite the hydrogen. Inferring Why are alkali metals stored under mineral oil or kerosene?
39 A + BC B + AC Single Replacement metal replaces metal nonmetal replaces nonmetalA + BC B + AC
40 Classifying Reactions 11.2Classifying ReactionsThe activity series of metals lists metals in order of decreasing reactivity.
43 Classifying Reactions 11.2Classifying ReactionsA double-replacement reaction is a chemical change involving an exchange of positive ions between two compounds.Aqueous solutions of potassium carbonate and barium chloride react in a double-replacement reaction to form the white precipitate barium carbonate. Potassium chloride, the other product of the reaction, remains in solution.
47 Classifying Reactions 11.2Classifying ReactionsA combustion reaction is a chemical change in which an element or a compound reacts with oxygen, often producing energy in the form of heat and light.Methane gas reacts with oxygen from the surrounding air in a combustion reaction to produce carbon dioxide and water. Inferring What else is produced in this reaction?
53 11.2 Section Quiz.1. What type of reaction is described by the following equation?6Li + N2 2Li3Na) combination reactionb) decomposition reactionc) single-replacement reactiond) combustion reaction