Bellringer:4/9/2018 In your bellringer notebook count how many atoms are in the following compounds: H2SO4 b) KClO3 c) NH3 d) O2 STOTD **QUIZ on Thursday: Balancing Equations & Types of Chemical Reactions **Lab on FRIDAY

Chemical Reactions Chapter 7

Chemical Reactions Chemical Reaction Evidence of a Chemical Reaction Process that rearranges atoms into different substances Evidence of a Chemical Reaction Temperature change Production of light Color change Production of gas Creation of a precipitate (solid) end

Chemical Equations Chemical Equations There are 2 parts in a chemical equation: Reactants To the Left of the arrow Products To the Right of the arrow The state of matter is shown with an: (s), (l), (g), (aq) aq- aqueous (dissolved in water) 2 H2(g) + O2(g)  2 H2O(l) Yields/Forms/Produces end

Chemical Equations Put a box around the reactants, and underline the products 2 H2 + O2  2 H2O Zn + H2SO4  ZnSO4 + H2 2 HgO  2 Hg + O2 end

Chemical Equations The Law of Conservation of Matter Matter cannot be created or destroyed! Every atom at the start of a reaction, must be at the end! To account for every atom you must balance the equation end

Chemical Equations NEVER Change the Subscripts Steps to balancing chemical equations: Write the chemical equation List the elements on each side of the equation Place coefficients in front of each formula Distribute (multiply) the element by the coefficient Balance 1 element at a time! If you need part of an atom, multiply everything by 2 Double check your work!!! NEVER Change the Subscripts end

Chemical Equations Lets practice: ___ N2 + ___ H2  ___ NH3 ___ KClO3  ___ KCl + ___ O2 ___ NaCl + ___ F2  ___ NaF + ___ Cl2 ___ CH4 + ___ O2  ___ CO2 + ___ H2O ___ P + ___ O2  ___ P2O5 end

Chemical Equations Practice! Balance the following ___ Na + ___ I2  ___ NaI ___ N2 + ___ O2  ___ N2O ___ KI + ___ Cl2  ___ KCl + ___I2 ___ N2 + ___ H2  ___ NH3

Chemical Equations Word Equations Names are written out instead of the formulas. To solve: Box the Reactants and Underline the Products Write the formula of each reactant and product Don’t forget to separate: Each formula with a “+” The reactants and products with an “” end

Chemical Equations Write and balance the following equations: Potassium oxide combines with water to make potassium hydroxide Aluminum plus oxygen gas forms aluminum oxide Nitrogen gas plus oxygen gas react and form dinitrogen pentoxide end

Chemical Equations Practice: Hydrogen plus oxygen yield water Nitrogen plus hydrogen yield ammonium Aluminum bromide plus chlorine yield aluminum chloride and bromine

Bellringer: 4/10/2018 Balance the following chemical equations: ___ NaBr + ___ Ca(OH)2  ___ CaBr2 + ___NaOH ___ Na + ___ I2  ___ NaI Safety Tip of the Day

Chemical Reactions There are 5 basic chemical reactions: Synthesis Decomposition Single Replacement Double Replacement Combustion end

Chemical Reactions Synthesis A + B  AB 2 Ca + O2  2 CaO 2 or more reactants combine to form 1 product A + B  AB 2 Ca + O2  2 CaO end

Chemical Reactions Decomposition AB  A + B NH4NO3  N2O + 2 H2O 1 reactants breaks down into 2 or more products AB  A + B NH4NO3  N2O + 2 H2O CuCl2  Cu + Cl2 end

Chemical Reactions Single Replacement A + BC  AC + B 1 element replaces another element in a compound A + BC  AC + B Cu + 2 AgNO3  2 Ag + Cu(NO3)2 3 Mg + 2 AlCl3  2 Al + 3 MgCl2 end

Chemical Reactions Double Replacement AB + CD  AD + CB The reactants switch partners AB + CD  AD + CB These reactions often produce water, a gas , or a solid NaOH + HCl  NaCl + H2O LiI + AgNO3  AgI + LiNO3 end

Chemical Reactions Combustion CH4 + 2 O2  CO2 + 2 H2O Oxygen combines with a compound to give off heat and light Forms CO2(g) and H2O(l) CH4 + 2 O2  CO2 + 2 H2O end

Chemical Reaction Classify the following: 2 H2 + O2  2 H2O Zn + H2SO4  ZnSO4 + H2 2 HgO  2 Hg + O2 AgNO3 + NaCl  AgCl + NaNO3 2 C2H6 + 7 O2  4 CO2 + 6 H2O end

Bellringer: 4/11/2018 What are the 5 basic chemical reactions and their general equations? Classify the following: SO3 + H2O  H2SO4 CaCl2 + F2  CaF2 + Cl2 2 NaCl  2 Na + Cl2 3. Safety Tip of the Day

Bellringer: How do you know if a reaction is endothermic? How do you know if a reaction is exothermic? Provide an example of an exothermic chemical reaction. STOTD

Energy Changes Chemical Energy Energy stored in chemical bonds 2 Types: Exothermic Endothermic end

Energy Changes Exothermic Reaction AB + CD  AD + CB + energy gives off energy produces heat and/or light ex) burning paper, Instant heating pad, glow sticks energy given off will be written as a product AB + CD  AD + CB + energy Na + Cl2  NaCl + 411kJ Energy measured in kilojoules end

Energy Changes In an exothermic reaction: Reactants have more energy than the products end

Energy Changes Endothermic Reaction AB + CD + energy  AD + CB Absorbs energy Surroundings get colder Ex) Instant icepacks energy taken in will be written as a reactant AB + CD + energy  AD + CB 15000 kJ + 6 CO2 + H2O  C6H12O6 + 6 O2 Energy measured in kilojoules end

Energy Changes In an endothermic reaction: Reactants are lower in energy than products end

Activity With a partner: In your notes write the question, “How can you make a chemical reaction go faster?” With your partner brainstorm answers to the question and write them down. Be prepared to share your answers

Reaction Rates Reaction Rate How fast the reactants change to products There are 5 ways to make a reaction go faster: Temperature Surface Area Stirring Concentration Catalysts end

Reaction Rates 1. Temperature Adding heat makes molecules move faster Move Faster = Faster Reaction 2. Surface Area Grind up a substance into a powder More Surface Area = Faster Reaction 3. Stirring Stirring makes things move around More Movement = Faster Reaction 4. Concentration Adding more reactants makes it easier for them to combine More Reactants = Faster Reaction end

Reaction Rates Catalyst Speeds up a reaction without being used in the reaction Lowers the amount of energy needed to get the reaction started (the size of the hill) Less Energy Needed = Faster Reaction end

Energy Changes end