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

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 MASSMATTER cannot be created or destroyed

-atoms are NOT __________ or __________

# atoms in REACTANTS = # atoms in PRODUCTS

VIDEO CLIP

REACTANTS/PRODUCTS

created destroyed

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

ENDOTHERMIC REACTIONS: -absorbs energyCOLD -need MORE energy to form new bonds in

productsEx: photosynthesisEXOTHERMIC REACTIONS: -releases energyHOT -need MORE energy to break bonds in reactantsEx: sodium + chlorine table salt

DEMO

ENERGY of REACTIONS

activation energy:-least amount energy needed to start a reaction---------------------------------------------------------------------------CATALYST-substances that __________activation energy

needed-anything that ________________ a chemical

reaction--------------------------------------------------------------------

---------

ENZYMES

LOWERS

speeds up

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 substancesNATURALLY PRESENT in FRUIT / RAW FOOD

ENZYMES

-lower activation energy needed-speeds up reactions in living things

Each ENZYME usually “participates” in ONE type of reaction

substrates—REACTANT

substrate binds to active site in enzyme

enzyme changes shape

enzyme releases product

ENZYMESLABEL 3 parts of process with brief description

ANALOGY: PUZZLE--right pieces fit--bend puzzle to change shape--pieces will pop out

NAME some biological processes that require enzymatic activity-

-muscle contraction

-cell division

-digestion

ENZYMES/ BIOLOGICAL ENZYMES

ENZYMES/ BIOLOGICAL ENZYMES: (EX/uses)

PROTEASE-secreted in pancreas / activated in small intestine-break down proteins-amino acids needed for body

LIPASE-produced by the pancreas-break down fats-used in digestion

AMYLASE-produced by pancreas /present in saliva-breaks down starch to sugar

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

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 cellEnzyme A Enzyme B

EXPLAIN why--maximal activity around 37ºC

6.2 CHEMICAL REACTIONS

AFTER YOU READExplain the role of chemical reactions in living things

All processes in living things are controlled by chemical reactions

BONDS in REACTANTS molecules/compounds

break

ATOMS rearrange

new bonds form in PRODUCTSCH4 + 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

REACTANTS/PRODUCTS

Element symbol

Element name # atoms in REACTANT

# atoms in PROCUCT

C carbonH hydrogenO oxygen

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

ENZYMES

enzyme

substrate

catalyst

act energy

EXOTHERMIC REACTION

Energy of PRODUCT is

LOWER than energy of REACTANTS

ENDOTHERMIC REACTION

Energy of PRODUCT is

HIGHER than energy of REACTANTS

energy is absorbed gets COLD

energy is releasedgets HOT

ENERGY of REACTIONS

DEMO

EXOTHERMIC—release energy

HOTENDOTHERMIC—absorb energy

COLD

ENERGY of REACTIONS

SUMMARIZE:

ENZYMES

Activity levelaffected by:temp/pH

Purpose:speed up reactions

Composed of:proteins

Reusable?yes

ENZYMES

PARTICIPATES IN HOW MANY DIFFERENT TYPES OF REACTIONS? 1-Specific to each enzyme

INTERPRET: pathway of reaction with an enzyme present

ENZYMES

ILLUSTRATE enzyme-substrate complex in cartoon form

ENZYMES

ENZYMESANALYZE the role of catalysts in chemical

reactions-speed up the reactionDESCRIBE the importance of enzymes in living

organisms-allow all biological functions to occur