CHEM125C                                                                                                    Fall, 2003

Hourly Exam # 1                                                                                             Dunnivant

 

Name (PRINTED) ____________________________________

 

There are 95 points.  The exam will be graded on a percentage basis.

 

The honor statement must be signed in order for your exam to be graded.

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

I have neither given nor received aid on this exam.  

                                                            Signature ________________________

 

AvogadroÕs number = 6.022 x 1023 items/mol           

amu = 1.6605 x 10-24 g/amu

electron charge = 1.602 x 10-19 C

mass of neutron = 1.6749 x 10-24 g

mass of electron = 9.1094 x 10-28 g

mass of proton = 1.6726 x 10-24 g

2.540 cenitmeters/ inch

453.6 grams/pound

1.057 quarts/L

 

This exam will be graded on a 100% basis.

 

NOTES:

Show all work for partial credit.   Significant figures and units will be graded throughout the exam.

 

 

  1. (5 pts) What is the difference between a molecule and a compound?

 

  1. (5 pts) Using the meter (m) as the base unit, what (how much) do the following units represent?

 

Example:         milli     10-3

 

Giga               

 

Centi               

 

Nano              

 

Kilo                

 

Pico                

 

 

  1. (10 pts) Today the temperature is supposed to reach 85oF.  What is this temperature in degrees C and degrees K?

 

  1. (5 pts) Convert 0.5000 pounds of water (at 4oC) to centiliters.

 

  1. (10 pts) Discuss the evolution of our ŅpictureÓ or concept of an individual atom.  You should also mention (not discuss, just give the name of the research or experiment) any key experiment that lead to the new version of the atom.

 

  1. (5 pts) Where did Mendeleev go wrong with the design of the periodic table?

 

  1. (20 pts) Name of give the chemical symbol of the following:

 

BH4                                  

 

Copper (II) oxide             

 

Sodium chlorate               

 

Lead dichromate   

 

Potassium permanganate

 

NaH2PO4                         

 

Ni3(PO4)2                         

 

Co(NO3)2                         

 

CaCO3                              

 

CdS                                  

 

 

  1. (10 pts) Calculate the gram atomic weight (amu version in the periodic table) for iron-52.  Use the data on page 1 to complete this problem.

 

Why does the mass not equal 52.00?

 

  1. (10 pts) Complete and balance the following reactions:

 

Na(s) + H2O ¸

 

Ca(s) + H2O ¸

 

Na(s) +  Cl2  ¸

 

CaO + H2O  ¸

 

Al(s)  +  HCl  ¸

 

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

 

  1. (10 pts) Lithium and nitrogen react to produce lithium nitride, a product that can be sold.  Nitrogen is cheap; our atmosphere is 80% N2. On the other hand, lithium cost money.  If you start with 50.0 g of each reactant:

 

1)determine the limiting reactant

 

2)create a complete flow chart for the  reaction below

 

3)determine how much (in grams) will be left over of the other reactant.

 

Li(s)  +  N2(g)  ¸  Li3N(s)

 

 

12.  (5 pts) (true or false)  For reactions that have a 1 to 1 stoichiometry with respect to the reactants, the limiting reactant will always be the reactant with the highest molecular weight.