Name:  _____________________                              date:  __________________               period: _______

Ch.7  chemical equations                     test                               35 points (2 ec)                                    chemistry

1.Write the chemical equation, including a notation if it’s a solid, gas, liquid, or dissolved in water, as appropriate.  Do not need to balance the chemical equation, but need to use the correct chemical formula.  [20 points]

a. In the combustion of methane gas, CH4, in the presence of oxygen gas, carbon dioxide gas and water vapor are formed.

b.  Mixing aqueous solutions of barium nitrate and potassium phosphate form a precipitate (i.e. a solid) of barium phosphate and an aqueous solution of potassium nitrate

c. The principal natural ore of lead is galena, which is primarily lead(II) sulfide.  Lead(II) sulfide can be converted to lead(II) oxide and sulfur dioxide gas by heating strongly in air.  Lead(II) oxide can then be heated with elemental carbon (coke), producing pure lead metal and carbon dioxide gas.  Write the chemical equations for the reaction of (i) lead(II) oxide and carbon, and (ii) lead(II) sulfide and oxygen gas.  [based on HW problem 27]

2. Fill-in the below blank using the lowest ratio of integers; if the coefficient is 1, then write “1”.  [17 points; weekly quiz problems]

a. ____  C2H6   +   ___  O2  -->  ____ CO2   +   ___ H2O

b.  ____  CaCl2  +  ___ Na3PO4  -->   ____  NaCl  +   ____  Ca3(PO4)2

c.  ___ C2H5OH   +  ____  O2  -->  ___  CO2   +  ___ H2O

d. ____  sodium carbonate  + ___  hydrogen chloride -->  ___ sodium chloride +  ____ water +  ____ carbon dioxide