Chemistry 100                                                                                     Dunnivant

Exam 2                                                                                                Spring, 2004

 

Name (printed)  _____________________

 

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

 

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

                                                                                                Signature


 

 

 

 


  1. (7.5 pts) Thorium 90 has a mass number of 234 and decays by emission of an alpha particle.  What is the element and mass number of the element created?  Write a balanced equation for the reaction.

 

 

 

 

 

 

 

 

  1. (7.5 pts) Phosphorus 15 has a mass number of 30 and decays by positron emission.  What is the mass number and element created?

 

 

 

 

 

 

 

 

  1. (3 pts) What is the radioactive dose of a typical American?

 

 

 

 

 

  1. (2 pts) Where does most of the dose in question number three come from?

 

 

 

 

 

 

 

  1. (10 pts) The half-life of barium-131 is 12.0 days.  How many grams of barium-131 will be left after 50 days, if you start with 100. grams?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. (10 pts) Using the following reactions (you should know the products), how many moles of HNO3 will be formed if you start with 1.5 moles of N2.  assume all reactions go to completion.

 

N2  +  O2 

 

NO  +  O2 

 

NO2  +  OH*  

 

 

 

 

 

 

 

 

 

  1. (15 pts) A combustion reaction starts with 20.5 grams of C8H16 and burns to completion in the presence of O2.  Fill in a complete flow chart showing how much of each product will be formed.

 

 

 

 

 

 

 

Sheet for question 7.

 

 

 

 

 

 


  1. (5 pts) a)Sulfur is a common component in coal.  With balanced reactions, show how a strong acid can be formed from burning coal in the presence of oxygen.

 

 

 

 

 

 

 

 

 

 

 

 

 

    (5 pts) b)Show, with reactions and words, how this can overcome the capacity of

    carbonic acid and calcium carbonate in natural water and soil.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   (5 pts)  c)How is acid rain toxic?

 

 

 

 

 

 

 

 

9.  (5 pts) What is the molecular weight of C5H4O?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  (5 pts)  What is the molar concentration when 25.4 g of Na2CO3 is dissolved in 0.560L of water?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(5 pts)  What is the concentration (in ppm) when 14.0 grams of Hg2+ is present in 100. liters of water?

 

 

 

 

 

 

 

 

 

 

  1.  (10 pts) What is the oxidation state (valence charge) on each atom in the following reaction?

 

 

Zn(s)    +  MnO2    +    NH4Cl        ZnCl2      +     Mn2O3     +     NH3     +     H2O

 

 

 

 

 

 

 

 

 

What is being oxidized?

 

 

 

What is being reduced?

 

 

 

 

 

 

11.  (5 pts) Why do we need the amu and Avogadros number?  Specifically explain what each does for us.