Answers to Second Worksheet



1. In chemical reactions, the total weight of the products equals
  the total weight of the reactants.
                                                                         
2. State the Law of Definite Proportions.
   In all samples of a given compound the elements in the
   compound are present in the same proportions.

3. Write symbols for the following elements.

   lithium    Li    carbon      C     oxygen    O
   neon       Ne    magnesium   Mg    silicon   Si
   sulfur     S     argon       Ar    calcium   Ca
   titanium   Ti    chromium    Cr    iron      Fe
   nickel     Ni    zinc        Zn    arsenic   As
   bromine    Br    strontium   Sr    radium    Ra
   silver     Ag    tin         Sn    iodine    I
   lanthinum  La    platinum    Pt    mercury   Hg

4. Name the elements having the following symbols:

     B  boron      N  nitrogen   F  fluoride   Na sodium
     Al aluminum   P  phosphorus Cl chloride   K  potassium
     V  vanadium   Mn manganese  Co cobalt     Cu copper
     Ge germanium  Cd cadmium    Ba barium     W  tungsten
     Au gold       Pb lead       Th thorium    U  uranium

5. Write the formulae for the following substances:

   water          H2O           carbon dioxide      CO2
   ammonia        NH3           sulfuric acid       H2SO4
   hydrogen gas   H2            oxygen gas          O2
   ozone          O3            nitrogen gas        N2
   sucrose        C12H22O11     glucose             C6H12O6

6. Indicate whether each of the following substances is
  molecular or ionic:

             H2O     M         NaCl      I

             CaO     I         NO        M

             Cl2     M         CCl4      M

             CO2     M         Al2O3     I

             HNO3    M         P4        M


7. Balance the following chemical equations:

   2H2    +   O2       -->       2H2O

   2Ca    +   O2       -->       2CaO

   4Al    +   3O2      -->       2Al2O3

   2Al    +   3F2      -->       2AlF3

   2Na    +   Br2      -->       2NaBr

   2NaOH  +   H2SO4    -->       Na2SO4    +     2H2O

   2C2H2  +   5O2      -->       4CO2      +     2H2O