630 likes | 647 Views
CONCLUSION to the BLUE LAB!. H ow do we know chemical reaction happened yesterday?. H ow do we know chemical reaction happened yesterday?. major, unexplained, color change major, unexplained temperature change major, unexplained bubbles gas created precipitate forms.
E N D
How do we know chemical reaction happened yesterday? • major, unexplained, color change • major, unexplained temperature change • major, unexplained bubbles gas created • precipitate forms.
We have already learned about 3 general types of chemical reactions:
Which two below need oxygen? • OXIDATION reactions NEED O2as REACTANT
Which two below need oxygen? • OXIDATION reactions NEED O2as REACTANT • combustion • corrosion
What are the two ways heat &/or other energy can flow in & out of a reaction? • OXIDATION reactions NEED O2as REACTANT • combustion/fire • corrosion/rusting • E • E
We have already learned about 3 general types of chemical reactions: • OXIDATION reactions NEED O2as REACTANT • combustion/fire • corrosion/rusting • EXOTHERMIC reactions RELEASE HEAT (or other energy)! • ENDOTHERMIC reactions ABSORB HEAT!
Can you recognize which type of reaction it is just by its chemical reaction formula? HEATBa(OH)2+ 8 H2O + 2 NH4Cl → 2 NH3 + 10 H2O +BaCl2
ENDOTHERMIC! This is the chemcial reaction for that cold pack. HEATBa(OH)2+ 8 H2O + 2 NH4Cl → 2 NH3 + 10 H2O +BaCl2
ENDOTHERMIC! This is the chemcial reaction for that cold pack. HEAT+ Ba(OH)2 + 8 H2O + 2 NH4Cl → 2 NH3 + 10 H2O +BaCl2
General types of chemical reactions: • OXIDATION reactions NEED O2as REACTANT • combustion/fire • corrosion/rusting • EXOTHERMIC reactions RELEASE HEAT (&/or other energy)! • ENDOTHERMIC reactions ABSORB HEAT (&/or other energy)!
Can you recognize which type(s) of reaction it is just by its chemical reaction formula? 2 Cu + O2 2 CuO
OXIDATION! See how oxygen is the reactant in how copper corrodes. 2 Cu + O2 2 CuO
OXIDATION! See how oxygen is the reactant in how copper corrodes. 2 Cu + O2 2 CuO OXIDATION reactions are also EXOTHERMIC
Chemical reactions can fit more than one category… • OXIDATION reactions NEED O2as reactant • combustion/fire • corrosion/rusting/tarnishing • EXOTHERMIC reactions RELEASE HEAT! • ENDOTHERMIC reactions ABSORB HEAT!
Can you recognize which type of reaction it is just by its chemical reaction formula?
BOTH EXOTHERMIC & OXIDATION! THIS IS AN EXOTHERMIC COMBUSTION REACTION OF OCTANE IN YOUR CAR ENGINE!
ALL OXIDATION reactions are all EXOTHERMIC! • OXIDATION reactions NEED O2as reactant • combustion/fire • corrosion/rusting/tarnishing • EXOTHERMIC reactions RELEASE HEAT! • ENDOTHERMIC reactions ABSORB HEAT!
What was yesterday’s reaction? 2 Cu + 4 HC2H3O2 Cu2(C2H3O2)4+ 2 H2
It was EXOTHERMIC for SURE, but not with OXYGEN GAS as a reactant • OXIDATION reactions NEED O2as reactant • combustion/fire • corrosion/rusting/tarnishing • EXOTHERMIC reactions RELEASE HEAT! • ENDOTHERMIC reactions ABSORB HEAT!
THAT WAS THE OL’ SWITCHEROO! 2 Cu + 4 HC2H3O2 Cu2(C2H3O2)4+ 2 H2
THERE’S A FEW MORE GENERAL TYPES OF CHEMICAL REACTIONS we should know. • OXIDATION reactions NEED O2as reactant • combustion • corrosion • EXOTHERMIC reactions RELEASE HEAT! • ENDOTHERMIC reactions ABSORB HEAT! • REPLACMENT reactions
THERE’S A COUPLE MORE GENERAL TYPES OF CHEMICAL REACTIONS we should know. • OXIDATION reactions NEED O2as reactant • combustion • corrosion • EXOTHERMIC reactions RELEASE HEAT! • ENDOTHERMIC reactions ABSORB HEAT! • REPLACEMENT reactions-switcheroo!!
Can you see why it’s called photoSYNTHESIS!?? 12 small molecules here 1 BIGGER molecule
Can you see why it’s called photoSYNTHESIS! phytoplankton & plants take 6 small molecules of carbon dioxide & water and turn it into 1 BIG glucose!
THERE’S A FEW MORE GENERAL TYPES OF CHEMICAL REACTIONS we should know. • OXIDATION reactions NEED O2as reactant • combustion • corrosion • EXOTHERMIC reactions RELEASE HEAT! • ENDOTHERMIC reactions ABSORB HEAT! • REPLACEMENT reactions—switcheroo!! • SYNTHESIS reactions BUILDS things UP
THERE’S A FEW MORE GENERAL TYPES OF CHEMICAL REACTIONS we should know. • OXIDATION reactions NEED O2as reactant • combustion • corrosion • EXOTHERMIC reactions RELEASE HEAT! • ENDOTHERMIC reactions ABSORB HEAT! • REPLACEMENT reactions—switcheroo!! • SYNTHESIS reactions BUILDS things UP! • DECOMPOSITION reactions BREAKS DOWN
LET’S DO A DECOMPOSITION REACTION!! • LET’S BREAK DOWN HYDROGEN PEROXIDE!
How can we SPEED a reaction up? • This can take months…most decomposition reactions do.
How can we SPEED areaction up? • ADD A CATALYST (substance that speeds up a reaction WITHOUT getting involved) • chlorophyll in photosynthesis • salt for water electrolysis • sulfuric acid for oxidizing sugar
Catalysts are substances that speed reactions up without changing themselves… • Like a baby walker helps a newborn walk… • …BUT is unchanged.
Catalysts are substances that speed reactions up without changing themselves… • Like slippery OIL helps the engine run faster… • …BUT is unchanged.
How can we SPEED the reaction up? • ADD A CATALYST (substance that SPEEDS up a reaction WITHOUT getting involved) • chlorophyll in photosynthesis • salt for water electrolysis • sulfuric acid for oxidizing sugar • H2O2 for speeding up our blue lab
WHAT’S HAPPENING HERE? IRON (Fe) RUSTS (CORRODES) IN WATER BUT THE RUST REACTION IS: 4 Fe + 3 O2 2 Fe2O3
WHAT’S HAPPENING HERE? IRON (Fe) RUSTS (CORRODES) IN WATER BUT THE REACTION IS AN OXIDATION REACTION AND HAS NO WATER IN IT: 4 Fe + 3 O2 2 Fe2O3 WHY DO WE CONNECT (ASSOCIATE) WATER (H2O) WITH RUSTING WHEN IT ISN’T EVEN A REACTANT?
REMEMBER OUR WATER QUALITY INDICATORS? N,T or P then DO
DISSOLVED OXYGEN (DO) DEFINITION: • the amount oxygen GAS (O2) bubbles dissolved in the water
GOOD DO CAUSES: MORE DISSOLVED OXYGEN LESS DISSOLVED OXYGEN • turbulence (waves, rapids), • REGULAR phytoplankton algae & plant growth (photosynthesis releases O2 in water) GOOD for the water!!!
LOW DO CAUSES: LESS DISSOLVED OXYGEN • higher temperatures(More O2 escapes, possibly from high turbidity or power plants!) • High nitrate levels/when algae blooms die & decomposers poop! BAD for water!!
Dissolved Oxygen RESULTS: • When dissolved oxygen drops too low, FISH CAN’T BREATHE what little oxygen is there! • Look for contributing causes! • thermal pollution (T to high) • too much nitrates • high turbidity
WATER IS A CATALYST IN RUSTING! IRON (Fe) RUSTS (CORRODES) IN WATER BUT THE REACTION IS AN OXIDATION REACTION AND HAS NO WATER IN IT: H2O 4 Fe + 3 O2 2 Fe2O3 WATER (H2O) SPEEDS UP RUSTING/CORROSION BY HOLDING OXYGEN GAS ONTO THE STEEL.
How can we SPEED the reaction up? • ADD A CATALYST (substance that speeds up a reaction but IT DOESN’T CHANGE) • chlorophyll in photosynthesis • water holds O2 onto steel to speed up oxidation
Molecules move faster when heated. The hotter it is, the quicker it COOKS.
How can we SPEED the reaction up? • ADD A CATALYST (substance that speeds up a reaction without getting involved) • chlorophyll in photosynthesis • water holds O2 onto steel to speed up oxidation • INCREASE TEMPERATURE (speeds up the molecules to react faster) • warming up our potassium permanganate & glycerin reaction