Chemistry 100                                                                                     Dunnivant

Exam 2                                                                                                Spring, 2005

 

Name (printed)  _____________________

 

Closed notes, closed book, closed Internet, closed neighbor!

 

I have neither given nor received aid on this exam.  __________________________

                                                                                                Signature

 

**NO SPARE PAPER IS ALLOWED OUT DURING THE EXAM.  YOU MAY NOT LEAVE THE ROOM OTHER THAN TO GO TO THE RESTROOM OR A SCHEDULED CLASS.

 

**POINTS WILL BE TAKEN OFF FOR SLOPPY WORK WHEN I CANNOT FIND YOUR ANSWER OR FIGURE OUT WHAT YOUÕRE DOING.

 

AvogadroÕs number = 6.022 x 1023 particles per mol

 

 

  1. (10 pts) Draw the diagram showing how the trajectories of the three basic radioactive particles were separated using electrical potentials.  Explain why each trajectory occurs it does.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. (a; 3 pts)  What is the average annual dose of radiation that each of us receive?

                 

                  ___________________ in mrem

 

 

 

      (b; 3 pts)  How much of the dose from part a is due to radon?

 

                  ___________________ in mrem

 

 

      (c; 3 pts)  Approximately how much of the dose from part a is natural and artificial (human caused)?

 

natural       ___________________ in mrem

 

 

 

artificial     ___________________ in mrem

 

 

      (d; 1 pt)  What dose of radiation  causes death?

 

     

                  ___________________ in rems

 

 

 

  1. (15 pts)  A waste site contains 1000. grams of a radioactive element with a half-life of 10.4 years.  How much radioactivity will remain after 155.8 years?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. (5 pts) Which compound has the fastest reaction rate constant, one with a half-life of 12 hours or one with a half-life of 12 days?

 

Answer:  ________________

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. (5 pts)  Two numbers were developed by scientists to give us the concept and actual numbers for the mole.  Name these two numbers and tell me what each does for us.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. (5 pts)  What is the mole and why do we need it?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. (25 pts) We studied combustion reactions.  Say that you burn 8.97 g of C8H18 (octane; what is in gasoline) in the presence of O2.  Complete a neat and orderly flow chart for reaction, clearly showing the mass (in grams) and moles of each reactant and product.  Use the back side of the previous page if you need more space.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. (5 pts)  If you have 139.5 grams of lead (Pb), how many moles and molecules do you have?

 

Moles: _________________

 

Molecules: ____________________

 

If you place the mass of Pb in 5.00 L of water, what is the molar concentration?

 

Molar concentration:  __________________

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. (0.5 pts each) Name

 

three strong acids:       _____________________

                                    _____________________

                                    _____________________

 

three strong bases:       _____________________

                                    _____________________

                                    _____________________

 

two weak acids:           _____________________

                                    _____________________

 

two weak bases:          _____________________

                                    _____________________

 

 

  1. (5 pts) Atmospheric gases as normal temperatures are stable and do not react.  However, all high temperature processes in the atmosphere create a strong acid from natural gases in the atmosphere.  Show all of the reactions leading to this formation.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. (5 pts)  Nitric and sulfuric acid react with gibbsite (Al(OH)3) in the soil to produce a toxic environment.  Show all of the reactions starting with the strong acids that lead to this. (You do not need to show how the strong acids are formed in the atmosphere, only show the reactions once they are present in water.)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. (0.62 pts each)  For the following reaction, the formation of rust from iron metal,

 

Fe  +  O2  ==>  Fe2O3

 

What is the oxidation state of the reactant Fe? __________

 

What is the oxidation state of the reactant O2?  ___________

 

What is the oxidation state of Fe in the product?  __________

 

What is the oxidation state of O in the product?  ___________

 

What is the oxidizing agent?  ______________

 

What is the reducing agent?  ______________

 

Is the reactant Fe being oxidized or reduced?  ___________

 

Is the reactant O2 being oxidized or reduced?  ____________