6.2 CHEMICAL REACTIONS WHAT YOU WILL LEARN -the parts of a chemical reaction -how energy changes relate to chemical reactions -the importance of enzymes in organisms MAIN IDEA: Chemical reactions allow living things to grow, develop, reproduce, and adapt

REACTANTS/PRODUCTS CHEMICAL REACTION--process in which atoms are reorganized to make new substances: CH4 + 2O2 → CO2 + 2H2O REACTANTS → PRODUCTS -subscript: # of atoms -coefficient: # of molecules -: direction of reaction EXPLAIN: What is the relationship between a chemical bond and a chemical reaction? -chemical BONDS created/broken by chemical REACTIONS

REACTANTS/PRODUCTS CONSERVATION of MASS MATTER cannot be created or destroyed -atoms are NOT __________ or __________ # atoms in REACTANTS = # atoms in PRODUCTS VIDEO CLIP created destroyed

BALANCE EQUATIONS ____Mg + ____HCl  ____MgCl2 + ____ H2 Mg= Mg= 1- DETERMINE # atoms for each element –track w/tallies 2- PICK an element that is NOT equal on both sides of the equation 3- ADJUST your # atoms on each side of equation so both are equal 4- USE coefficients to show the # of atoms of each element on each side ____Mg + ____HCl  ____MgCl2 + ____ H2 Mg= Mg= H= H= Cl= Cl= ____H2O2  ____H2O + ____O2 H= H= O= O= EXPLAIN why chemical equations must be balanced: -matter neither created or destroyed

BALANCE EQUATIONS ____N2 + ____H2 → ____NH3 ____HCl + ____NaOH → ____NaCl + ____H20 ____C6H12O6 +____O2 → ____CO2 + ____H20

ENERGY of REACTIONS ENDOTHERMIC REACTIONS: -absorbs energyCOLD -need MORE energy to form new bonds in products Ex: photosynthesis EXOTHERMIC REACTIONS: -releases energyHOT -need MORE energy to break bonds in reactants Ex: sodium + chlorine  table salt DEMO

ENERGY of REACTIONS ENDOthermic EXOthermic

ENERGY of REACTIONS EXOthermic -EXOthermic reaction: EXPLAIN why energy of product might be LOWER than the energy of reactants- -EXOthermic reaction: energy in form of heat/light is released during reaction

-absorbs energy (HEAT) ENERGY of REACTIONS endo or exo? -barium hydroxide (s) + octahydrate (s) + ammonium thiocyanate (s) -barium thicyanate + ammonia (g) + water (l) Ba(OH)2 + 8H2O + 2NH4SCN  Ba(SCN)2 + 10H2O +2NH3 DEMO ENDOTHERMIC -absorbs energy (HEAT)

-release energy (HEAT) ENERGY of REACTIONS endo or exo? -hydrogen peroxide (l) + iodine (l) iodine (l) + water (l) + oxygen (g) aka- elephant toothpaste DEMO EXOTHERMIC -release energy (HEAT)

ENZYMES activation energy: -least amount energy needed to start a reaction --------------------------------------------------------------------------- CATALYST -substances that __________activation energy needed -anything that ________________ a chemical reaction ----------------------------------------------------------------------------- LOWERS speeds up

Each ENZYME usually “participates” in ONE type of reaction ENZYMES Enzyme ANIMATION -special proteins -biological catalysts -COMPOSED OF: -protein -PURPOSE: -speeds up rate of chemical reactions in biological process -REUSABLE: -YES--not used up in reaction -ACTIVITY LEVEL AFFECTED/INFLUENCED BY: -pH, temperature, other substances NATURALLY PRESENT in FRUIT / RAW FOOD -lower activation energy needed -speeds up reactions in living things Each ENZYME usually “participates” in ONE type of reaction

ENZYMES LABEL 3 parts of process with brief description substrates—REACTANT  substrate binds to active site in enzyme enzyme changes shape enzyme releases product ANALOGY: PUZZLE--right pieces fit--bend puzzle to change shape--pieces will pop out

ENZYMES/ BIOLOGICAL ENZYMES NAME some biological processes that require enzymatic activity- -muscle contraction -cell division -digestion

ENZYMES/ BIOLOGICAL ENZYMES: (EX/uses) PROTEASE -secreted in pancreas / activated in small intestine -break down proteins -amino acids needed for body AMYLASE -produced by pancreas /present in saliva -breaks down starch to sugar LIPASE -produced by the pancreas -break down fats -used in digestion

REVIEW/PRACTICE 1- What principle can be applied to all chemical reactions? conservation of mass reactants formed from products coefficient principle   2- The minimum amount of energy needed for a chemical reaction is called: principle mass absorbent energy activation energy 3- What is the function of the enzyme-substrate? destroy the enzyme break and form chemical bonds stop chemical reactions 4- In which of the following are bonds broken and new bonds formed? polar molecules chemical reactions isotopes 5- Which statement is true of chemical reactions? bonds break in reactants  bonds break in products products have fewer atoms than reactants

REVIEW/PRACTICE 6-DESCRIBE the importance of enzymes to living organisms -speeds up biological chemical reactions 7- IDENTIFY/DESCRIBE 2 factors that can influence enzyme activity. -temp, pH, substrate concentration

REVIEW/PRACTICE 10- DESCRIBE the effect temperature has on the rate of the reactions.  -temp increases the rate of both reaction within specific ranges 9- INFER which enzyme is more active in a human cell Enzyme A Enzyme B EXPLAIN why- -maximal activity around 37ºC

6.2 CHEMICAL REACTIONS AFTER YOU READ Explain the role of chemical reactions in living things All processes in living things are controlled by chemical reactions

REACTANTS/PRODUCTS reactants → products BONDS in REACTANTS molecules/compounds break  ATOMS rearrange new bonds form in PRODUCTS CH4 + 2O2 → CO2 + 2H2O reactants → products subscript: # atoms in molecule coefficient: # of molecules

REACTANTS/PRODUCTS CALCULATE the number of atoms of each element in the chemical equation: CH4 + 2O2 → CO2 + 2H2O ANAYLYZE—is equation balanced? STATE principle that explains why # atoms in reactants = # atoms in products Element symbol Element name # atoms in REACTANT # atoms in PROCUCT C carbon H hydrogen O oxygen

ENZYMES MATCHING -____________min energy required for reactants to form products -____________substance lowers energy needed to start reaction -____________protein that is biological catalyst -____________molecule binds to an enzyme act energy catalyst enzyme substrate

Energy of PRODUCT is HIGHER than energy of REACTANTS ENERGY of REACTIONS EXOTHERMIC REACTION  Energy of PRODUCT is LOWER than energy of REACTANTS ENDOTHERMIC REACTION  Energy of PRODUCT is HIGHER than energy of REACTANTS energy is released gets HOT energy is absorbed gets COLD DEMO

ENERGY of REACTIONS EXOTHERMIC—release energy HOT ENDOTHERMIC—absorb energy COLD

ENZYMES SUMMARIZE: Reusable? Composed of: yes proteins ENZYMES Activity level affected by: temp/pH Purpose: speed up reactions PARTICIPATES IN HOW MANY DIFFERENT TYPES OF REACTIONS? 1-Specific to each enzyme

ENZYMES INTERPRET: pathway of reaction with an enzyme present

ENZYMES ILLUSTRATE enzyme-substrate complex in cartoon form

ENZYMES ANALYZE the role of catalysts in chemical reactions -speed up the reaction DESCRIBE the importance of enzymes in living organisms -allow all biological functions to occur