 Name two signs of a chemical reaction.  Here are the signs of a chemical reaction that we saw in yesterday’s lab.  Color Change  Release of Gas  Formation of a precipitate  Change in temperature

 A synthesis reaction is one in which two or more substances react to produce a single product.  The generic equation for a synthesis reaction is listed below: A + B  AB

 When two elements react to form a product the reaction is always considered a synthesis reaction. 2Na (s) + Cl 2 (g)  2NaCl (s)

 Synthesis reactions can also apply to compounds. Example: CaO (s) + H 2 O  Ca(OH) 2(s)

 This type of reaction can also apply to a reaction with an element and a compound. Example: 2SO 2 (g) + O 2 (g)  2SO 3 (g)

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 In a combustion reaction oxygen combines with a substance and releases energy in the form of heat and light.  Combustion reactions are quite common because Oxygen may combine with many different substances.

 In this example, the reaction between hydrogen and oxygen. When hydrogen is heated, water is formed and a large amount of energy is released. 2H 2 (g) + O 2 (g)  2H 2 O (g)

 Coal when burned is another example of a combustion reaction.  A large amount of energy is released when coal is burned.  Questions:  Can you think of some examples of coal being used for energy?  What is coal classified as? (hint it’s part of a product that we use every day to get to school)

 Some combustion reactions may be considered synthesis reactions as well.

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 A decomposition reactions is one in which a single compound breaks down into two or more elements or new compounds. The generic Example: AB  A + B

 Decomposition reactions often require an energy source.  What kinds of energy do you think it this reaction would typically require?

 A decomposition reaction is one in which a single compound breaks down into one more products. Examples: NH 4 NO 3(s)  N 2 O (g) + 2H 2 O (g) 2NaN 3(s)  2Na (s) + 3N 2(g)

 Can you think of any real world examples of a decomposition reaction?

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 A single replacement reaction is one in which the atoms of one element replace the atoms of another element in a compound. The generic example: A + BX  AX + B

Example: Cu (s) + 2AgNO 3(aq)  2Ag (s) + Cu(NO 3 ) 2(aq)

Example: 2Li (s) + 2H 2 O (l)  2LiOH (aq) + H 2(g) I/AAAAAAAAAo8/_mbFcN0yO7o/s1600/Lithium+and+water.jpg

 A metal will not always replace another metal in a compound dissolved in water.  It depends on the reactivity of the metal. A metal’s reactivity is its ability to react with another substance.  Go to figure 10-10, p. 288 in your textbook to see the activity series.

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 Another type of single replacement reaction involves the replacement of a nonmetal in a compound by another nonmetal.  Halogens are typically involved in these kinds of reactions.  Halogens, like metals, have different levels of activity.

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 A double replacement reaction is a chemical reaction that involves the exchange of positive ions between two compounds and produces either a precipitate, a gas, or water.

Generic Equation: AX + BY  AY + BX  A and B represent the positively charged ions. X and Y represent the negatively charged ions.  In a double replacement reaction X will replace Y.  The ions switch sides with the ion most like it. So in other words each ion will either switch with the other positive ion if it’s positive or vise versa.

Examples: Ca(OH) 2(aq) +2HCl (aq)  CaCl 2(aq) + 2H 2 O (l) 2NaOH (aq) +CuCl 2(aq)  2NaCl (aq) + Cu(OH) 2(aq)  Looking at these two chemical reaction, identify the positively charged ions and the negatively charged ions. Write it down in your chemistry journals.

 A key characteristic of a double replacement reaction is the formation of a certain type of product. Either a,  Precipitate Which is a solid produced in solution during a chemical reaction.  Gas  Water

 Table 10-2 from your textbook can be helpful Guidelines for Double-Replacement Reactions StepExample 1. Write the components of the reactants in a skeleton equation. Al(NO 3 ) 3 + H 2 SO 4 2. Identify the cations and anions in each compound. Al(NO 3 ) 3 has Al 3+ and NO 3 - H 2 SO 4 has H + and SO Pair up each cation with the anion from the other compound. Al 3+ pairs with SO 4 2- H + pairs with NO Write the formulas for the products using the pairs from step 3. Al 2 (SO 4 ) 3 HNO 3 5. Write the complete equation for the double-replacement reaction Al(NO 3 ) 3 + H 2 SO 4  Al 2 (SO 4 ) 3 +HNO 3 6. Balance the equation.2Al(NO 3 ) 3 + 3H 2 SO 4  Al 2 (SO 4 ) 3 + 6HNO 3

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Predicating Products of Chemical Reactions Class of ReactionReactantsProbable Products Synthesis Two or more substances One compound Combustion A metal and oxygen A nonmetal and oxygen A compound and oxygen The oxide of the metal The oxide of the nonmetal Two or more oxides Decomposition One Compound Two or more elements and/or compounds Single-Replacement A metal and a compound A nonmetal and a compound A new compound and the replaced metal A new compound and the replaced nonmetal Double-Replacement Two compounds Two different compounds, one of which is often a solid, liquid or a gas

 Exit Ticket  Name one thing that you learned about chemical reactions today.

 Textbook:  Chemistry : Matter and Change. Copyright McGraw-Hill Companies, Inc.  Youtube  All demonstration videos were taken from Youtube. Links are on the PowerPoint  Google Images  All of the images were taken from Google images (the websites are credited under the pictures).  All other images were taken from Microsoft PowerPoint ClipArt.