WELCOMEWELCOME

Introduction to Introduction to Chemical ReactionsChemical Reactions

SUBMITTED BY SUBMITTED BY V V

ISHNU.S.PILLAIISHNU.S.PILLAI PHYSICAL PHYSICAL

SCIENCESCIENCE

Main IdeasMain IdeasChemical Reactions are Chemical Reactions are represented by Chemical represented by Chemical Equations.Equations.Chemical Equations are Chemical Equations are balanced to show the same balanced to show the same number of atoms of each number of atoms of each element on each side.element on each side.

Chemical Chemical Reactions are Reactions are EverywhereEverywhereCookingCooking RespirationRespiration

Chemical Chemical Reactions are Reactions are EverywhereEverywhereHair DyeHair Dye Auto FuelAuto Fuel

Representing Representing Chemical Chemical ReactionsReactionsChemists observe chemical reactions and Chemists observe chemical reactions and

have come up with a way to represent or have come up with a way to represent or model what is happening.model what is happening.

Making NaCl

Solid Sodium combines with Chlorine gas Solid Sodium combines with Chlorine gas to make solid Sodium Chloride:to make solid Sodium Chloride:

2Na (s) + Cl2 (g) 2Na (s) + Cl2 (g) 2NaCl2NaCl

Chemical Equations are Chemical Equations are different from Numerical different from Numerical

EquationsEquationsNumerical Equation: 3x + 2y = 47Numerical Equation: 3x + 2y = 47

Chemical Equation 2Na + Cl2 Chemical Equation 2Na + Cl2 2NaCl 2NaCl

ReactantA + Reactant B ReactantA + Reactant B Product Product

The reactants are used up in forming The reactants are used up in forming the productthe product

The arrow The arrow shows the direction of the shows the direction of the reactionreaction

Symbols used in Symbols used in Chemical Chemical EquationsEquationsSymbol Purpose

+ Separates more than one reactant or product

Separates reactants from products. Indicates direction of

reaction(s) Identifies a solid state

(aq) Identifies that something is dissolved in water

(l) Identifies liquid state

(g) Identifies gaseous state

Balancing EquationsBalancing EquationsAfter you write a chemical equation you have to After you write a chemical equation you have to balance it to make sure that the same number balance it to make sure that the same number

of atoms of each element are on each side.of atoms of each element are on each side.How would you balance this equation?How would you balance this equation?

Li + H2O Li + H2O H2 + LiOH H2 + LiOH

Steps to Balancing a Chemical Steps to Balancing a Chemical EquationEquation

Example Example ContinuedContinued

Change the Coefficients to make the Change the Coefficients to make the number of atoms of each element equalnumber of atoms of each element equal

Balance the Hydrogens:Balance the Hydrogens:

CH4 + O2 CH4 + O2 CO2 + CO2 + 2 2 H2O H2O

Balance the Oxygens: Balance the Oxygens:

CH4 + CH4 + 2 2 O2 O2 CO2 CO2 + + 22 H2OH2O

THANK THANK YOUYOU