October 29, 2015 Objective: Explain the driving forces behind chemical reactions. Homework: Wksht p. 49 (Girls-even, Boys-odd) Do Now: Solve the following and include correct Sig Figs. a)How many moles are in 1.5g of iron? b)What mass of aluminium in grams is in 15.1 moles of aluminium?

November 3, 2015 Objective: Explain the driving forces behind chemical reactions. Do Now: Find the following: a)The gram formula mass of Cu(SO 4 ) x 5H 2 O b)The number of moles in 35g of Al 2 (SO 4 ) 3 c)The mass, in grams, of 2.5 moles of Mg 3 (PO 4 ) 2

Nature of Chemical Reactions 5.1

Chemical Reactions When substances undergo chemical changes, they form new substances. Atoms are rearranged, because bonds are broken and reformed

Chemical Reactions Signs are: 1.evolution of heat and light 2.color change 3.gases emitted 4.a precipitate (solid) forms

Chemical Equations Reactants substances that will undergo a chemical change. (Left side )

Chemical Equations Products substances that are formed as a result of a chemical change. (Right side)

Examples water + mix + eggs → cake 6CO 2 + 6H 2 O → C 6 H 12 O 6 + 6O 2 Reactants Products

Energy and Reactions Every reaction needs energy to get things started. This energy is needed to break the chemical bonds of the reactants.

Energy and Reactions Usually comes in the form of heat, electricity, sound or light.

Chemical Energy Energy stored within an atom and is released when a substance reacts. Stored energy is known as Potential Activation Energy

Reaction takes place No reaction takes place

Endothermic reaction Reaction where heat energy is absorbed. Surroundings get colder chemical energy of products greater than reactants

Examples Ice pack placed on your skin Photosynthesis NH 4 NO 3 reacting with water becomes very cold

Exothermic Reaction Reaction where heat energy is released surrounding get hotter Chemical energy of reactants greater than products reactants

Examples Match being lit Firecracker exploding NaOH reacting with water will get hotter.

Reaction Types 5.2

Synthesis Reaction A reaction when two substances form at least one new, more complex compound.

Synthesis Reaction two or more reactants = one product

Synthesis Reaction EXAMPLE: A + B  A B 2Fe + O 2  2FeO

Decomposition Reaction A reaction in which one compound breaks into at least two products. Reactant decomposes into parts

Decomposition Reaction one reactant = two or more products

Decomposition Reaction EXAMPLE: AB  A + B 2 NI 3  N 2 + 3I 2

Combustion reaction Reaction in which a compound and oxygen burn. Oxygen (O 2 ) always is a reactant

Combustion reaction CO or CO 2 will always be a product H 2 O will always be a product

Combustion reaction C 2 H 5 0H + 3O 2  2CO 2 + 3H 2 O

Single displacement Reaction one element another compound.A reaction in which atoms of one element take the place of atoms of another compound.

Single displacement Reaction Example X A + B  B A + X 3CuCl 2 + 2Al  2AlCl 3 + 3Cu

Double Replacement Reaction twoA reaction in which the apparent exchange of ions between two compounds.

Double replacement reaction AX + BY  AY + BX Pb(NO 3 ) 2 +K 2 (CrO 4 ) → Pb(CrO 4 ) + 2K(NO 3 )

Nov 9, 2015 Objective: Demonstrate the law of conservation of mass through balancing equations. Do Now: 1) Classify the following equations: Zn + 2HCl  ZnCl 2 + H 2 2NaHCO 3  Na 2 CO 3 + H 2 O + CO 2 2) Then, tell me the # (amount) of each element on the reactant side and product side. Are both equations balanced? Homework: Worksheet p58 #1-8

Balancing Chemical Equations 5.3

Balancing All equations must have the same type and number of atoms on each side of the equation. Law of Conservation of Mass Tells you the amounts

Rule to Balancing Can only change coefficients and never subscripts. Always balance O and H last if water is in the equation. Balance the polyatomic ions first if present

Mole Ratios Coefficients show the amount of moles of each substance. Mole ratio is the smallest relative number of moles of the substance involved in a reaction. 2H 2 + O 2 → 2H 2 O = 2:1:2

Practice Phet Game ancing-chemical-equations ancing-chemical-equations P 165

November 10, 2015 Objective: Demonstrate the law of conservation of mass through balancing equations. Do Now: 1) Balance the following equation and tell me the type of chemical reaction it is: Fe + O 2  Fe 2 O 3 2) Turn on your tablets and open up Google Chrome Homework: Study Quizlet Ch 5. 2 strategies and 1 test (90%). Test Thursday.

Rates of Change 5.4

What is a Rate? The speed at which it takes something to occur. It is not a time!!!!! m/s, mi/hr, potato/min

Factors Affecting RXN Rates Temperature Surface Area Concentration Catalysts

Temperature Higher the temperature the faster the reaction. Higher temperature causes particles to move faster.

Surface Area The amount of particles that are exposed. The greater the surface area the faster the reaction. Breaking things into pieces increases the surface area.

Concentration The more concentrated the solution the faster the reaction will be. More concentrated = less diluted.

Which has a higher concentration of reactants? More concentrated

Catalyst A substance that changes the rate of chemical reactions without being consumed.

Catalyst Catalysts speed up reactions. (enzymes) Inhibitors slow down reactions (preservatives)

Rate of Reaction Graph

Review Balance this: C 2 H 5 0H + O 2  CO 2 + H 2 O Fe + O 2  FeO CuCl 2 + Al  AlCl 3 + Cu

Convert What is the gram formula mass of NaOH? What is the mass in grams of moles of H 2 S? How many moles are in moles of H 2 S?