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Chapter 11: Chemical Reacitons 11.1 Describing Chemical Reactions.

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Presentation on theme: "Chapter 11: Chemical Reacitons 11.1 Describing Chemical Reactions."— Presentation transcript:

1 Chapter 11: Chemical Reacitons 11.1 Describing Chemical Reactions

2 Signs of a Chemical Reaction Color change Solid forms (precipitate) Bubbles (gas) produced Change in temperature

3 Writing Chemical Equations Word Equations To 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 11.1

4 Writing Chemical Equations Chemical Equations A 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). 11.1

5 Writing Chemical Equations A 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 + O 2  Fe 2 O

6 Writing Chemical Equations A catalyst is a substance that speeds up the reaction but is not used up in the reaction. Without Catalyst With Catalyst 11.1

7 Writing Chemical Equations 11.1

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9 for Conceptual Problem 11.1

10 Balancing Chemical Equations To 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. 11.1

11 Balancing Chemical Equations This 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. 11.1

12 Balancing Chemical Equations A 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. 11.1

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 SO 4 ” instead of “1 S” and “4 O”

14

15 for Conceptual Problem 11.2

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18 Example Solid calcium metal reacts with water to form aqueous calcium hydroxide and hydrogen gas.

19 Example Hydrogen peroxide in an aqueous solution decomposes to produce oxygen and water

20 Example Solid copper metal reacts with aqueous silver nitrate to produce solid silver metal and aqueous copper (II) nitrate

21 Practice 1) Solid mercury (II) oxide decomposes to produce liquid mercury metal and gaseous oxygen 2) Solid carbon reacts with gaseous oxygen to form gaseous carbon dioxide

22 Practice 3) Gaseous ammonia reacts with gaseous hydrogen chloride to form solid ammonium chloride 4) Iron metal reacts with oxygen gas to form solid iron (II) oxide

23 Practice 5) Solid magnesium reacts with liquid water to form solid magnesium hydroxide and hydrogen gas 6) Gaseous ammonia reacts with gaseous oxygen to form gaseous nitrogen monoxide and gaseous water

24 Practice 7) Nitrogen monoxide gas reacts with hydrogen gas to form nitrogen gas and water 8) 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 + oxygen b) propane + oxygen + water  carbon dioxide c) propane + oxygen + water + carbon dioxide d) propane + oxygen  water + carbon dioxide

26 2.Which of the following is a skeleton equation? a) H 2 + CO  CH 3 OH b) 2H 2 + CO  CH 3 OH c) 2H 2 + CO 2  CH 3 OH d) hydrogen + carbon monoxide  methanol 11.1 Section Quiz.

27 3.What coefficient for H 2 SO 4 is required to balance the following equation? Ca 3 (PO 4 ) 2 + ____ H 2 SO 4  3CaSO 4 + 2H 3 PO 4 a) 1 b) 2 c) 3 d) Section Quiz.

28 11.2 Types of Chemical Reactions

29 Classifying Reactions The five general types of reaction are combination, decomposition, single- replacement, double- replacement, and combustion. 11.2

30 Classifying Reactions A combination (synthesis) reaction is a chemical change in which two or more substances react to form a single new substance. 11.2

31 Combination only one product A + B  AB

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33 for Conceptual Problem 11.4

34 Classifying Reactions A decomposition reaction is a chemical change in which a single compound breaks down into two or more simpler products. 11.2

35 Decomposition only one reactant AB  A + B

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37 for Conceptual Problem 11.5

38 Classifying Reactions A single-replacement reaction is a chemical change in which one element replaces a second element in a compound. 11.2

39 Single Replacement metal replaces metal nonmetal replaces nonmetal A + BC  B + AC

40 Classifying Reactions The activity series of metals lists metals in order of decreasing reactivity. 11.2

41

42 for Conceptual Problem 11.6

43 Classifying Reactions A double-replacement reaction is a chemical change involving an exchange of positive ions between two compounds. 11.2

44 AB + CD  AD + CB Double Replacement

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46 for Conceptual Problem 11.7

47 Classifying Reactions A 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. 11.2

48

49 for Conceptual Problem 11.8

50 Classify 1) 2K + Cl 2 → 2KCl 2) Fe 2 O 3 + 2Al → Al 2 O 3 + 2Fe 3) 2Mg + O 2 → 2MgO 4) HNO 3 + NaOH → H 2 O + NaNO 3 5) KBr + AgNO 3 → AgBr + KNO 3

51 Classify 6) PbO 2 → Pb + O 2 7) 2C 2 H 2 + 5O 2 → 4CO 2 + 2H 2 O 8) 2Ni + 4O 2 → 2NiO 9) 4NH 3 + 5O 2 → 4NO + 6H 2 O 10) S 8 + 8O 2 → 8SO 2

52 Classify 11) 2Al + Cl 2 → 2AlCl 3 12) 2AlN → 2Al + N 2 13) BaCl 2 + Na 2 SO 4 → BaSO 4 + 2NaCl 14) 2Cs + Br 2 → 2CsBr 15) KOH + HCl → H 2 O + KCl

53 1. What type of reaction is described by the following equation? 6Li + N 2  2Li 3 N a) combination reaction b) decomposition reaction c) single-replacement reaction d) combustion reaction 11.2 Section Quiz.

54 2. Balance and indicate reaction type. H 2 SO 4  H 2 O 2 + SO 2 a) H 2 SO 4  H 2 O 2 + SO 2, combination reaction b) H 2 SO 4  H 2 O 2 + SO 2, decomposition reaction c) H 2 SO 4  2H 2 O 2 + SO 2, combination reaction d) H 2 SO 4  2H 2 O 2 + SO 2, decomposition reaction

55 11.2 Section Quiz. 3. Predict the missing product in the following unbalanced equation. Pb(NO 3 ) 2 + KOH  KNO 3 + ____ a) PbOH 2 b) Pb(OH) 4 c) Pb(OH) 2 d) PbOH


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