Balancing Chemical Equations

1. Count the number of atoms on each side.

____H2 + ____O2 ____H2O1

Reactants Products

H= 2 H=2

O= 2 O=1

2. See that there are more O’s on the left than the right. Both sides need to have the same number of atoms.

3. Whatever number you put in front of a compound effects all element in the compound.

4. You cannot change the subscript in an equation.

5. If there are ( ) with a subscript the subscript effects all elements in the compound. (PO4)2 so P=2 O=8

6. If there is no subscript ex. O it is always a 1for ex O1.

____H2 + ____O2 ____H2O

Reactants Products

H= 2 H=2

O= 2 O=1

____H2 + ____O2 __2__H2O1

Reactants Products

H= 2 H=2

O= 2 O=1

BALANCED!

__2__H2 + ____O2 __2__H2O1

Product Reactants

H= 4 H=4

O= 2 O=2

Give the number of atoms present for each of the following compounds.

CompoundCompound Number of AtomsNumber of Atoms

Pb(NO3)2 Pb=_____ N=_____ O=______

H2SO4 H=_____ S=_____ O=______

Fe2(SO4)2 Fe=_____ S=_____ O=______

1 2 6

2 1 4

2 2 8

Fill in the missing part. 2_______ + Cl2 2 NaCl

____ + F2 2HF

2_____ + O2 Ag2 O2

Zn + 2H2O Zn + 2H2 + 2___

SnO2 + 2C 2CO + _____

2 NO + _______ 2NO2

Na

H2

Ag

O

Sn

O2

Na= Na=

O= O=

1. ______ Na + ______ O2 ______ Na2O

2. ______ H2 + ______ O2 _________H2O

3. _____ Na2SO4 + _____ CaCl2 _____CaSO4 + ____ NaCl

H= H=

O= O=

O= O=

Ca= Ca=

Cl= Cl=

Na= Na=

S= S=

Al= Al=

O= O=

4. ______ Al2O3 ______Al + ______O2

5. ______ N2 + ______ H2 _________H2N

6. _____ Fe + _____ H2O _____Fe3O4 + ____ H2

N= N=

H= H=

Fe= Fe=

H= H=

O= O=

P= P=

O= O=

7. ______ P2 + ______ O2 _________P4O10

8. ______ C2 H6 + ______ O2 ______ CO + _______H2O

9. _____SiCl4 ______Si + ______Cl2

C= C=

H= H=

O= O=

Si= Si=

Cl= Cl=

C= C=

H= H=

10. ______ C + ______ H2 _________CH4

2. ______ H3PO4 + ______ KOH ______K3PO4 + ______ H2O

H= H=

P= P=

O= O=

K= K=

3. ______K + ______ B2O3 ______K2O + ______B

K= K=

B= B=

O= O=

4. ______HCl + ______NaOH ______NaCl + ______H2O

H= H=

Cl= Cl=

Na= Na=

O= O=

5. ______Na + ______NaNO3 ______Na2O + ______N2

Na= Na=

N= N=

O= O=6. ______ C + ______S8 ______CS2

C= C=

S= S=7. ______Na + ______O2 ______Na2O2

Na= Na=

O= O=

8. ______N2 + ______O2 ______N2O2

N= N=

O= O=

9. _____ H3PO4 + _____Mg(OH)2 _____Mg3(PO4)2 + _____H2O

H= H=

P= P=

O= O=

Mg= Mg=10. ______NaOH + ______H2CO3 ______Na2CO3 + ______H2O

Na= Na=

O= O=

H= H=

C= C=

11. SKIP

K= K=

O= O=

H= H=

Br= Br=

12. ______H2 + ______O2 ______H2O2

H= H=

O= O=

13. ______Na + ______O2 ______Na2O

Na= Na=

O= O=14. ______Al(OH)3 + ______H2CO3 ______Al(CO3)3 + ______H2O

Al= Al=

O= O=

H= H=

C= C=

15. ______Al + ______S8 ______Al2S3

Al= Al=

S= S=

16. ______Cs + ______N2 ______Cs3 N

Cs= Cs=

N= N=

17. ______Mg + ______Cl2 ______Mg Cl2

Mg= Mg=

Cl= Cl=18. ______Rb + ______RbNO3 ______Rb2O + ______N2

Rb= Rb=

N= N=

O= O=19. ______ C6H6 + ______O2 ______CO2 + H2O

C= C=

H= H=

O= O=

20. ______N2 + ______H2 ______NH3

N= N=

H= H=

21. ______ C10H22 + ______O2 ______CO2 + H2O

C= C=

H= H=

O= O=

22.______Al(OH)3 + ______H2Br ______AlBr3 + ______H2O

Al= Al=

O= O=

H= H=

C= C=

23.____CH3+____CH2+____CH2+____CH3+____O2____CO2+ ____H2O

C= C=

H= H=

O= O=

24. ____C + ____O2 ____CO2

C= C=

O= O=

25. ____C3H8 + ____O2 ____CO2 + ____H2O

C= C=

H= H=

O= O=

26. ______ Li + ______AlCl3 ______LiCl + ______Al

Li= Li=

Al= Al=

Cl= Cl=

27. ____C2H6 + ____O2 ____CO2 + ____H2OC= C=

H= H=

O= O=

28. ____NH4OH + ____ H3PO4 ____(NH4)3PO4 + ____H2O

N= N=

H= H=

O= O=

P= P=

29. ______ Rb + ______P ______Rb3P

Rb= Rb=

P= P=

30. ______ CH4 + ______O2 ______ CO2 + ______H2O

C= C=

H= H=

O= O=

31.______Al(OH)3 + ______H2SO4 ______ Al(S)4)3 + ______H2O

Al= Al=

O= O=

H= H=

S= S=32. ______Na + ______Cl2 ______NaCl

Na= Na=

Cl= Cl=33. ______ Rb + ______S8 ______Rb2S

Rb= Rb=

S= S=34. _____ H3PO4 + _____Ca(OH)2 _____MCa3(PO4)2 + _____H2O

H= H=

P= P=

O= O=

Ca= Ca=

35. ______NH3 + ______HCl ______NH4Cl

N= N=

H= H=

Cl= Cl=36. ____Li + ____H2O ____LiOH + ____H2

C= C=

H= H=

O= O=

37.____ Ca3(PO4)2+ ____SiO2+ ____C _____CaSiO3+_____CO+_____P

Ca= Ca=

P= P=

O= O=

Si= Si=

C= C=

38. ______ NH3 + ______O2 ______N2 + ______H2O

N= N=

H= H=

O= O=

39. ______FeS2 + ______O2 ______Fe2O3 + ______SO2

Fe= Fe=

S= S=

O= O=40. ______C + ______SO2 _______CS2 + ______CO

C= C=

S= S=

O= O=

6 Types of Chemical Reactions

1) SYNTHESIS REACTIONIn a synthesis reaction two or more simple substances combine to form a more complex substance. Two or more reactants yielding one product is another way to identify a synthesis reaction. For example, simple hydrogen gas combined with simple oxygen gas can produce a more complex substance-----water!The chemical equation for this synthesis reaction looks like:

reactant + reactant -------> productA + B AB8 Fe + S8 8 FeS

To visualize a synthesis reaction look at the following cartoon:

  2) DECOMPOSITION REACTIONIn a decomposition reaction a more complex substance breaks down into its more simple parts. One reactant yields 2 or more products. Basically, synthesis and decomposition reactions are opposites.For example, water can be broken down into hydrogen gas and oxygen gas. The chemical equation for this decomposition reaction looks like:

reactant -------> product + productTo visualize a decomposition reaction look at the following cartoon:

The egg (the reactant), which contained the turtle at one time, now has opened and the turtle (product) and egg shell (product) are now two separate substances.

AB A + B2 H2O 2 H2 + O2

3) SINGLE REPLACEMENT (DISPLACEMENT) REACTIONIn a single replacement reaction a single uncombined element replaces another in a compound. Two reactants yield two products. For example when zinc combines with hydrochloric acid, the zinc replaces hydrogen. The chemical equation for this single replacement reaction looks like:

reactant + reactant ---------> product + productTo visualize a single replacement reaction look at the following cartoon:

Notice, the guy in the orange shirt steals the date of the other guy. So, a part of one of the reactants trades places and is in a different place among the products.

A + BC AC + BMg + 2 H2O Mg(OH)2 + H2

4) DOUBLE REPLACEMENT (DISPLACEMENT) REACTIONIn a double replacement reaction parts of two compounds switch places to form two new compounds. Two reactants yield two products. For example when silver nitrate combines with sodium chloride, two new compounds--silver chloride and sodium nitrate are formed because the sodium and silver switched places. The chemical equation for this double replacement reaction looks like:

reactant + reactant ---------> product + productTo visualize a double replacement reaction look at the following cartoon:

AB + CD ---> AD + CBPb(NO3)2 + 2 KI ---> PbI2 + 2 KNO3

Both of these reactions are special DOUBLE REPLACEMENT (DISPLACEMENT) REACTION.

5) Acid-base: This is a special kind of double displacement reaction that takes place when an acid and base react with each other. Generally, the product of this reaction is some ionic salt and water:

HBr + NaOH ---> NaBr + H2O

6) Combustion: A combustion reaction is when oxygen combines with another compound to form water and carbon dioxide. These reactions are exothermic, meaning they produce heat.

C10H8 + 12 O2 ---> 10 CO2 + 4 H2O

Six Types of Chemical Reaction Worksheet

Balance the following reactions and indicate which of the six

types of chemical reaction are being represented:

1) ____ NaBr + ____ Ca(OH)2 ___ CaBr2 + ____ NaOH

Type of reaction: _____________________________

Na= Na=

Br= Br=

Ca= Ca=

O= O=

H= H=

2) ____ NH3+ ____ H2SO4 ____ (NH4)2SO4

Type of reaction: _____________________________

N= N=

H= H=

S= S=

O= O=

3) ____ C5H9O + ____ O2 ____ CO2 + ____ H2O

Type of reaction: _____________________________

C= C=

H= H=

O= O=

4) ____ Pb + ____ H3PO4 ____ H2 + ____ Pb3(PO4)2

Type of reaction: _____________________________

Pb= Pb=

H= H=

P= P=

O= O=

5) ____ Li3N + ____ NH4NO3 ___ LiNO3 + ___ (NH4)3N

Type of reaction: _____________________________

Li= Li=

N= N=

H= H=

O= O=

6) ____ HBr + ___ Al(OH)3 ___ H 2O + ___ AlBr3

Type of reaction: _____________________________

H= H=

Br= Br=

Al= Al=

O= O=

7) What’s the main difference between a double displacement reaction and an acid-base reaction?

Acid-base reactions form water.

8) Combustion reactions always result in the formation of water. What other types of chemical reaction may result in the formation of water? Write examples of these reactions on the opposite side of this paper.

Acid-base: HCl + NaOH H2O + NaClSynthesis: 2 H2 + O2 2 H2ODecomposition: NH4OH NH3 + H2OSingle displacement: H2 + 2 NaOH 2 Na + 2 H2O (not common)