Chemistry 112
First Hour Exam
Name:____________
Please show all work for partial credit
1A . (10 points) Express the answer to 130000/17=
130000/17=7,647.06
In 2 significant figures _7600_
In 4 significant figures _7647_
In 6 significant figures _7647.06
How many significant figures should you use to express the answer to the following
calculations:
130000/17.00 __2 (130000 has 2 sig fig)
13000-17.00 ___2_
13000
17.00
12983, but round to 13000 to match digits
2. (10 points) Perform the following unit conversions:
24,835 nm to km
1 cup to mls
(1 cup = 8 fluid ounces)
38 miles/gal to km/liter
A 56 acre farm in Whitewood is selling for $280,000.
Express this price in cents/sq ft.
(1 acre = 160 rod2, 5 ½ yards = 1 rod)
2
3. (10 points) In class I talked about the way a chemist classifies matter. Classify the
following materials using this system
sand Heterogeneous mixture
Kool-Aid Homogeneous mixture
Water Pure substance - compound
Mercury Pure substance - element
The elementary particle that has mass but no charge
Neutron
4. (10 points) Dalton’s Atomic Theory contained for major thoughts or premises. What
were these four ideas.
All matter is composed of tiny particles called atoms
All atoms for a given element are identical; atoms from different elements are
different
A compound comes from the combination of a set of atoms
Chemical reaction involve the reorganization of atoms
5. (10 points) Identify the following elements, ions, or family:
An alkali metal in the 5th period ___Rb_____
A Noble gas in the 1st period __He______
An element with a mass number of 14, and an atomic number of 7___N______
An ion with a mass number of 39, an atomic number of 37 that contains
36 electrons
___Rb+____
A family of elements whose ions always have one more electron than they have
protons
Halides or halogens
3
6. (10 points) Give the names of the following compounds
Mg3N2 __Magnesium nitride
CaSO3 Calcium sulfite
Cr2O3 Chromium(III) oxide
ClF5 Chlorine pentafluoride
HCl(aq) Hydrochloric acid_
7. (10 points) Give the molecular formula of the following compounds
Magnesium chloride _MgCl2__________
Copper(IV) sulfide _CuS2_________
Copper(II) sulfate __CuSO4_________
Sulfur hexachloride __SF6______________
Nitrous acid __HNO2____________
8. (4 points) How many moles of carbon are there in 35.6 g of carbon?
9. (4 Points) As of 09/01/06 the world population is 6,541,161,782. How many moles of
people is this?
4
10A. (4 points) What is the molar mass of Cholesterol (C27H46O)?
Do this calculation to 5 significant figures
27(12.01) + 46(1.008) + 16.00 = 386.64 grams cholesterol / mole
10B. (4 points) If I have 1 gram of cholesterol, how many moles of cholesterol is this?
10C. (4 points) If I have 1 gram of cholesterol, how many molecules of cholesterol do I
have?
10D. (4 points) If I have 1 gram of cholesterol, how many atoms of C does this sample
contain?