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 I can read and understand the information contained within a chemical reaction.

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Presentation on theme: " I can read and understand the information contained within a chemical reaction."— Presentation transcript:

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2  I can read and understand the information contained within a chemical reaction

3 Chemical reactions involve changes in matter, the making of new materials with new properties, and energy changes. In a given reaction …. Symbols represent elements (H) Chemical formulas describe compounds (Al 2 O 3 )

4 reactantsproducts ◦ Chemical equations show the conversion of reactants (on the left of the arrow) into products (on the right of the arrow).  “+” sign separates molecules on the same side  The arrow is read as “yields”  Example C + O 2  CO 2  This reads “carbon plus oxygen yields carbon dioxide”

5 The charcoal used in a grill is basically carbon. The carbon reacts with oxygen to yield carbon dioxide. The chemical equation for this reaction, C + O 2  CO 2, contains the same information as the English sentence but has quantitative (numerical) meaning as well.

6 Chemical reactions depict the kind of reactants and products in a given chemical reaction and their relative amounts. Reactants are “what goes in” and Products are “what comes out!” 4 Al + 3 O 2 → 2 Al 2 O 3 The numbers in the front are called coefficients.

7  The coefficient in front of a given element in an equation can stand for a representative particle (one piece) of the substance OR a mole of the substance 4 Al + 3 O 2 ---> 2 Al 2 O 3 4 atoms of aluminum plus 3 molecules of oxygen gas yield two molecules of aluminum oxide OR 4 moles of aluminum plus 3 moles of oxygen gas yield two moles of aluminum oxide

8  (l) “liquid”; this indicates that a chemical is in liquid form. EX: H 2 O (l)  (aq) “aqueous”; this indicates that a chemical is dissolved. EX: NaCl (aq)  (g) “gaseous”; this indicates that a chemical is in gaseous form. EX: CO 2(g)  (s) “solid”; this indicates that a chemical is in solid form. EX: Mg(OH) 2(s)   “precipitate”; this indicates that a product is a solid precipitate. EX: CaCO 3   “delta” or “heat”; this symbol over the yields sign indicates that heat is added to move the reaction along.. EX:   ↑ “gas”; this indicates that a product is formed which is a gas, and forms bubbles. EX: H 2 ↑

9  I can differentiate between the different types of chemical reactions.

10 〉 How does learning about reaction types help in understanding chemical reactions? 〉 You can use patterns to identify kinds of chemical reactions and to predict the products of the chemical reactions.

11 There are five types of chemical reactions we will talk about: 1.Synthesis reactions 2.Decomposition reactions 3.Single replacement reactions 4.Double replacement reactions 5.Combustion You need to be able to identify the type of reaction

12 Synthesis reactions occur when two substances (generally elements but sometimes compounds) combine and form a compound reactant + reactant  1 product A + B  AB Example: 2H 2 + O 2  2H 2 O Example: C + O 2  CO 2

13 Here is another example of a synthesis reaction

14 Decomposition reactions occur when a compound breaks up into the elements or into a few simpler compounds 1 Reactant  Product + Product In general: AB  A + B Example: 2 H 2 O  2H 2 + O 2 Example: 2 HgO  2Hg + O 2

15 Another view of a decomposition reaction:

16 Single Displacement Reactions occur when one element replaces another in a compound. A metal can replace a metal OR a nonmetal can replace a nonmetal. element + compound  product + product A + BC  AC + B (if A is a metal) OR A + BC  BA + C (if A is a nonmetal)

17 Sodium chloride solid reacts with fluorine gas NaCl (s) + F 2(g)  NaF (s) + Cl 2(g) Note that fluorine replaces chlorine in the compound Aluminum metal reacts with aqueous copper (II) nitrate Al (s) + Cu(NO 3 ) 2(aq)  Cu (s) + Al(NO 3 ) 3(aq)

18 Another view:

19 Double Replacement Reactions occur when a metal replaces a metal in a compound and a nonmetal replaces a nonmetal in a compound Compound + compound  product + product AB + CD  AD + CB

20 Think about it like “foil”ing in algebra, first and last ions go together + inside ions go together Example: AgNO 3(aq) + NaCl (s)  AgCl (s) + NaNO 3(aq) Another example: K 2 SO 4(aq) + Ba(NO 3 ) 2(aq)  KNO 3(aq) + BaSO 4(s)

21 Combustion reactions occur when a hydrocarbon reacts with oxygen gas. These always produce CO 2 and H 2 O as products. In order to burn something you need the 3 things in the “fire triangle”: 1) A Fuel (hydrocarbon) 2) Oxygen to burn it with 3) Something to ignite the reaction (spark)

22 Examples C 5 H 12 + O 2  CO 2 + H 2 O and 5 6 8


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