BALANCING EQUATIONS

CHEMICAL EQUATIONS Chemical Equation: Represents, with symbols and formulas, the identities and relative molecular or molar amounts of the reactants and products in a chemical reaction. Chemical Equation: Identities and relative amounts of the reactants and products

COMPONENTS OF CHEMICAL EQUATIONS Al (s) + O 2 (g)  Al 2 O 3 (s) Reactants  Products Reactants: “Ingredients”, what you start with, left Products: “final materials”, what you end up with, right

COMPONENTS OF CHEMICAL EQUATIONS

CHEMICAL EQUATIONS INTO WORDS C (s) + O 2 (g)  CO 2 (g) Solid carbon plus oxygen gas react to yield carbon dioxide gas

COEFFICIENTS AND SUBSCRIPTS 4 Al (s) + 3 O 2 (g)  2 Al 2 O 3 (s) Coefficient : Number in front, tells the number of molecules Subscript: Number below, tells the number of atoms of an element in each molecule

COEFFICIENTS AND SUBSCRIPTS

4 Al (s) + 3 O 2 (g)  2 Al 2 O 3 (s)

COEFFICIENTS AND SUBSCRIPTS Ca(OH) 2 Subscripts outside of parentheses apply to everything inside the parentheses How many oxygens are present in each of the following? 1.NaOH 2.Ca(OH) Ca(OH) 2

LAW OF CONSERVATION OF MATTER Matter cannot be created nor destroyed

LAW OF CONSERVATION OF MATTER Because of the law of conservation of matter, an equation must be balanced! Equations must have the same number of atoms of each element on both sides of the equation

BALANCING EQUATIONS Skeleton Equation: Unbalanced equation, an equation without coefficients Balanced Equation: The number of atoms of each element are equal on both sides

BALANCING EQUATIONS When balancing chemical reactions you may add coefficients in front of the compounds to be balanced, but you may not change the subscripts Changing subscripts changes the compound. Subscripts are determined by the valance electrons (charges for ionic or electrons shared for covalent)

BALANCING EQUATIONS Mg + O 2  MgO

BALANCING EQUATIONS ___ C 3 H 8 (g) + ___ O 2 (g)  ___ CO 2 (g) + ___ H 2 O (g)

BALANCING EQUATIONS a)___ Mg + ___ HCl  ___ MgCl 2 + ___ H 2 b)___ Ca + ___ N 2  ___ Ca 3 N 2 c) ___ NH 4 NO 3  ___ N 2 O + ___ H 2 O

BALANCING EQUATIONS d) BiCl 3 + H 2 S  Bi 2 S 3 + HCl e) C 4 H 10 + O 2  CO 2 + H 2 O f) O 2 + C 6 H 12 O 6  CO 2 + H 2 O g) NO 2 + H 2 O  HNO 3 + NO h) Cr 2 (SO 4 ) 3 + NaOH  Cr(OH) 3 + Na 2 SO 4 i) Al 4 C 3 + H 2 O  CH 4 + Al(OH) 3

BALANCING EQUATIONS d) 2 BiCl H 2 S  1 Bi 2 S HCl e) 2 C 4 H O 2  8 CO H 2 O f) 6 O C 6 H 12 O 6  6 CO H 2 O g) 3 NO H 2 O  2 HNO NO h) 1 Cr 2 (SO 4 ) NaOH  2 Cr(OH) Na 2 SO 4 i) 1 Al 4 C H 2 O  3 CH Al(OH) 3

BALANCING EQUATIONS Back side of the worksheet is your homework!

STEPS TO BALANCE EQUATIONS 1.Write the correct formula for the reactants and the products. (Do not change the formula in later steps) 2.Find the number of atoms for each element on both sides 3.Determine where to place coefficients in front of formulas so that each element has the same number of atoms on both sides 4.Check your answer to see if: Equation is balanced Coefficients are in the lowest possible whole number ratios (reduced)