Chemical reactions
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Chemical Reactions. Chemical Reactions. New Substances produced by changing the way atoms are arranged Physical Changes ≠ Chemical Reaction Evidence Change in Color (rust) Temperature Change (endo/exo-thermic) Formation of a Gas Formation of a Solid (Precipitate).

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Chemical Reactions

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Chemical Reactions


Chemical Reactions

  • New Substances produced by changing the way atoms are arranged

  • Physical Changes ≠ Chemical Reaction

  • Evidence

    • Change in Color (rust)

    • Temperature Change (endo/exo-thermic)

    • Formation of a Gas

    • Formation of a Solid (Precipitate)


  • Reactants: Substances Present @ Beginning

  • Products: Substances Formed by the Reaction

  • Yields: An “equal sign” in a chemical reaction meaning “produces”, “creates”, or “forms”…

    Na + Cl2 NaCl

    Reactants Yields Products


Reaction Classifications


Synthesis

…Combining Elements…

A + B  AB

Mg + O2  MgO


Decomposition

…Separating Elements…

CD  C + D

H2O  H2 + O2

(+Electricity)


Combustion

…FIRE! (Needs Oxygen and produces CO2 )…

EF + O2 H2O + CO2

CH4 + O2 H2O + CO2


Single Replacement

…Switch out ONE element with another!...

GH + I  GI + H

CuCl2 + Zn  ZnCl2 + Cu


Double Replacement

…Switch Out Two Elements with Two Others!...

JK + LM  JM + KL

AgNO3 + HCl  AgCl + HNO3

(Stop Here)


Rate of Reaction

  • Concentration

    • High Concentration = faster reaction

  • Surface Area

    • More surfaces available to react = faster reaction

  • Temperature

    • Higher Temperatures = faster reaction

      • Particles speed up or slow down…speeding up or slowing down the reaction…


Rate of Reaction (Cont’d)

  • Catalyst

    • Something that speeds up the rate of reaction without being affected itself.

  • Inhibitor

    • Something that slows down the rate of reaction without being affected itself.

      (Stop Here)


The Law of Conservation of Mass

  • Matter Can Neither Be Created Nor Destroyed

  • Reactants and Products MUST be EQUAL!

    So…

    We Balance Chemical Equations!


Balancing Equations

  • Adding Coefficients to Reactants and Products in order to make both sides of the arrow EQUAL!

    Na + Cl2 NaCl

    Reactants Yields Products

    This Chemical Equation is WRONG! (Why??)

    Na: 1Na: 1

    Cl: 2Cl: 1

    The Numbers of Atoms are not BALANCED!


Balancing Equations (cont’d)

So….We add Coefficients to Make the Equation Balanced! We can NEVER EVER Add or Take Away Subscripts! EVER!!

Na + Cl2 NaCl

Na: 1Na: 1

Cl: 2Cl: 1

It is BALANCED!! WOO HOO!


Balancing Equations (Cont’d)

So…My Balanced, Correct Chemical Reaction Between Sodium and Chlorine is…

2Na + Cl2 2NaCl

This says that TWO atoms of sodium react with ONE diatomic molecule of chlorine and produces TWO molecules of sodium chloride!


Balancing: Your Turn

H2 + O2 H2O

H:H:

O:O:

Start By Setting it Up Like This 


Answer!

H2 + O2 H2O

H: 2H: 2

O: 2O: 1

¿¿¿ ¿¿¿Questions ??? ???


Balancing Practice

  • Try to balance the following reactions! You may check with a partner as you work!

  • Mg + O2 MgO

  • N2 + H2  NH3

  • Cl2 + KI  KCl + I2

  • Na + HCl H2 + NaCl


Balancing Practice – Answers!

  • 2Mg + O2 2MgO

  • N2 + 3H2  2NH3

  • Cl2 + 2KI  2KCl + I2

  • 2Na + 2HCl  H2 + 2NaCl


INB 93

  • Copy and complete the following flow map using your notes. Be sure to COLORCODE to match your notes! Add extra reminder “bubbles” as you go!

    How to Balance Chemical Equations

1) Count the number of ATOMS on each side of the chemical equation

H2 + O2 H2O

H: 2 H: 2

O: 2 O: 1

2. Add Coefficients on each side of the equation so that…

3. …Continue…


Videos!

  • Classifications 1 (1:30)

  • Classifications 2 (1:30)

  • Alkali Metals in Water(3 min)

  • Sodium in Water (1 min)

  • Dry Ice Eruptions (11 min)

  • Francium Bomb in Ocean (30 sec)

  • Chemistry Explosions (13 min)


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