CHEM125-C                                                                                                  Fall, 2004

Hourly Exam # 1                                                                                             Dunnivant

 

Name (PRINTED) ____________________________________

 

There are 100 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 ________________________

 

Avogadros 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

 

NOTES:

-Show all work for partial credit.  

-Significant figures and units will be graded throughout the exam.

 

  1.  (5 pts) Using the meter (m) as the base unit, give the symbol and what (how much) each of the following units represent?

Example:                                                                     symbol            scientific

                                                                                                            notation

milli                                                                             m                     10-3

 

deci (used to order drinks in Europe)                          _______          _______

 

centi (a common measure in science and Europe)       _______          _______

 

micro (used for very low concentrations)                    _______          _______         

 

Kilo (used for large weights, human body weights)   _______          _______                     

Mega (used in radio station frequencies)                     _______          _______         

 

  1. (5 pts) Today the temperature is supposed to reach 80.0oF.  What is this temperature in degrees C and degrees K?

 

(5 pts) A gallon of water weighs 7.44 pounds.  What is the weight of 1.00 gallon of water in milligrams?  Express your answer in scientific notation.

 

(5 pts)  Using the same 1.00 gallon of water what is the volume in milliliters (at 4oC)?  Express your answer in scientific notation.

 

  1. (10 pts) Name of give the chemical symbol of the following:

 

Na2SO3                

 

Copper (II) oxide             

 

Sodium carbonate             

 

Lead(II) chromate 

 

Potassium perchlorate

 

SrHPO4                            

 

CH3COOH                      

 

Co(NO3)2                         

 

Ca(HCO3)2

 

HgS                                  

 

 

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

 

K(s) + H2O

 

C2H6 + O2

 

Na(s) +  Cl2 

 

CaO + H2O 

 

Ni(II)(s)  +  HCl 

 

 

 

  1. (10 pts)  We discussed the mole and the amu.  Explain what each are from a conceptual standpoint, why we need them, and how they affect the structure of the Periodic table.  You MUST TYPE your answer, use a font size NO SMALLER THEN 12, and single space the text.  Limit your answer to 1/2 page.  In grading your answer I will fold the paper in half and only grade what is on the first half of the page. 

 

 

  1. (15 pts) You place 100.0 g of a hydrocarbon (C5H12) and 100.0 of O2 in a flask and allow them to react to completion.  How much of each product will be formed?

 

1)determine the limiting reactant:  answer:  _____________________

 

2)create a complete flow chart for the  reaction below in the space below

 

3)determine how much (in grams) of the reactant that is present in abundance will be left.

 

6.  (10 pts)  Calculate the weight percent of each element in KH2PO4.

 

 

  1. (10 pts)  Ascorbic acid (vitamin C) contains 40.92% C, 4.58% H, and 54.50% O by mass.  What is the empirical formula of ascorbic acid?  A separate experiment found that the molecular weight of vitamin C is 176.1.  What is its molecular formula?

 

Empirical formula:             __________________

 

Molecular formula:            __________________

 

  1. (15 pts) Answer ONE of the following questions.  Which ever question you choose, You MUST TYPE the answer using a 12 point font and LIMIT your answer (including figures) to ONE single spaced page.  Use every piece of data/evident that we discussed to defend your answer.

 

Contrast the experiments of Thompson and Rutherford.  Include in discussion that what the purpose of each experiment was, how the experiment was conducted (a drawing), and how the results of each experiment changed our concept of atomic structure.

 

Discussion the experiments that led to the determination of the mass of the electron.  Include drawing to explain your answer.

 

Explain why Daltons postulate atoms of an element are not changed into difference atoms in reactions; atoms are neither created nor destroyed is now proven wrong when we consider nuclear reactions.  Use drawing to explain your answer.