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Do Now for Wednesday, January 8 th !. Think! Think! Think!!!! Explain how a simple chemical reaction might save lives. Another Chemical Reaction Saves Lives !. Without Airbag With Airbag. The Chemistry Behind Airbags. Chemical Reactions Are Used to Generate the Gas Inside an Airbag.

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Do now for wednesday january 8 th
Do Now for Wednesday, January 8th!

  • Think! Think! Think!!!!

  • Explain how a simple chemical reaction might save lives.


Another chemical reaction saves lives
Another Chemical Reaction Saves Lives!

  • Without AirbagWith Airbag


The chemistry behind airbags
The Chemistry Behind Airbags

  • Chemical Reactions Are Used to Generate the Gas Inside an Airbag.

  • Airbags have been commonly available since the late 1980's; however, they were first invented (and a version was patented) in 1953. The automobile industry started in the late 1950's to research airbags and soon discovered that there were many more difficulties in the development of an airbag than anyone had expected. Crash tests showed that for an airbag to be useful as a protective device, the bag must deploy and inflate within 40 milliseconds.


The chemistry behind airbags1
The Chemistry Behind Airbags

  • The instant a collision happens, a pellet of sodium azide (NaN3) is ignited. A rapid chemical reaction occurs, generating nitrogen gas (N2). This gas fills a nylon bag at a velocity of 150 to 250 miles per hour. This process, from the initial impact of the crash to full inflation of the airbags, takes only about 40 milliseconds. Ideally, the body of the driver (or passenger) should not hit the airbag while it is still inflating.


Do now for friday january 10
“Do Now” for Friday, January 10

  • There are three basic types of chemical reactions. List and give an example of each.




Do now for wednesday january 8 th
A chemical equation is a shorter, easier way to show chemical reactions, using symbols instead of words.


Do now for wednesday january 8 th

5 Ways to know that a chemical reaction has occurred: chemical reactions, using symbols instead of words.1. Color Change2. Heat Produced-Gets Warm (exothermic)3. Heat Absorbed-Gets Cold (endothermic)4. Gas Produced (fizzzzz)5. Solid Produced (precipitate)These are indications of CHEMICAL CHANGES


Do now for wednesday january 8 th

Physical Changes do not tell you a chemical reaction has occurred!Physical change = phase changes from solidliquidgasChanges in shape










Chemical formulas
Chemical formulas… occurred!

  • Are the “words” in the language of chemistry

    In the last unit you learned how to name compounds and write their formulas. You learned some formula “words” like:

    Carbon Monoxide Carbon Dioxide Water Hydrogen Peroxide

    CO CO2 H2O H2O2


Do now for wednesday january 8 th

Chemical Equations are the “sentences” in the language of chemistry. Chemistry students put the “words” (formulas) together to make “sentences” (chemical equations)Every chemical equation has formulas as well as special symbols.


Do now for wednesday january 8 th

Basic rules for chemical equations of chemistry. Chemistry students put the “words” (formulas) together to make “sentences” (chemical equations)1. Chemical equations read from left to right.2. Each equation has two halves divided by an arrow. The half left of the arrow is the REACTANT side and the half rightof the arrow is the PRODUCT side.


So what do the numbers mean
So what do the numbers mean? of chemistry. Chemistry students put the “words” (formulas) together to make “sentences” (chemical equations)


We use subscripts to show the number of atoms of different elements in a formula
We use of chemistry. Chemistry students put the “words” (formulas) together to make “sentences” (chemical equations)SUBSCRIPTS to show the number of atoms of different elements in a formula.

We use COEFFICIENTS to balance an equation. Coefficients are numbers placed in front of a chemical formula in an equation and tell you how many atoms or molecules of each reactant and product are involved in the reaction.


Do now for wednesday january 8 th

RULES OF CHEMICAL EQUATIONS: of chemistry. Chemistry students put the “words” (formulas) together to make “sentences” (chemical equations)1. The Law of Conservation of Mass states that chemical equations must start and end with the same number of atoms of each substance on both sides of the arrow. We call this a BALANCEDchemical equation!


Do now for wednesday january 8 th

All chemical reactions must be balanced. This means that the number of atoms on the reactant side must be equal to the number of atoms on the product side.


Do now for wednesday january 8 th

2. To number of atoms on the reactant side must be equal to the number of atoms on the product side.balance the equation, you can ONLY change the coefficients, NOT the subscripts!(e.g., changing CO2to 3CO2is OK. Changing CO2to CO4is not.)


Do now for wednesday january 8 th

3. To number of atoms on the reactant side must be equal to the number of atoms on the product side.calculate the number of atoms for each atom, you MULTIPLY the coefficient times the subscripts (e.g., 3 CO2= 3 Carbons and 6 Oxygens)


Do now for wednesday january 8 th
4. You number of atoms on the reactant side must be equal to the number of atoms on the product side.MUST have only integer coefficients when you are finished, no decimals, no fractions! (e.g., 6.5 O2is not ok, 13 O2is ok)


5 you must have the lowest possible integer coefficients when you are finished
5. You number of atoms on the reactant side must be equal to the number of atoms on the product side.MUST have the lowest possible integer coefficients when you are finished.


Unbalanced
UNBALANCED number of atoms on the reactant side must be equal to the number of atoms on the product side.


Balanced
BALANCED! number of atoms on the reactant side must be equal to the number of atoms on the product side.


Three types of chemical reactions demonstrated by the flintstones
Three Types of Chemical Reactions number of atoms on the reactant side must be equal to the number of atoms on the product side.Demonstrated by the Flintstones!


Synthesis when two or more elements or compounds combine to make a more complex substance
Synthesis – When two or more elements or compounds combine to make a more complex substance.

2H2 + O2 2H2O

Synthesis of Water


Decomposition occurs when compounds break down into simpler products
Decomposition – Occurs when compounds break down into simpler products.

2H2O2 2H2O + O2

Decomposition of Hydrogen Peroxide


Replacement when one element replaces another in a compound
Replacement – When one element replaces another in a compound.

2Cu2O + C  4 Cu + CO2

Replacement of Oxygen in Copper Oxide


Practice
Practice! compound.