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Exam 1
Chemistry 1210
Spring 2002
Prof. Steve Scheiner
Feb 11, 2002
Instructions:
You may begin the exam at 10:30 AM. You have until 11:20 AM.
This exam has 25 questions. Each question is worth 4 points for a total of 100 points. You may use a calculator and may refer to a single sheet of paper with notes and formulae.
Use only a #2 Pencil to mark the best answer on the Scantron sheet. You will turn in only the Scantron sheet. You may keep the rest of the exam.
On the Scantron sheet, fill in your last name, first and middle initials, identification number (this is your social security number). Also fill in the appropriate bubbles. Also write a 4 digit (number/letter) secret code on the upper right of your scantron. Your grades will be posted by this secret code.
Your score on the exam will be sent to your University email address. The answer key will be posted on the course web page at
Useful Information:
A periodic table is found on the next page.
moles = mass/molecular weightDensity = mass/volumeAvogadro’s number = 6.02 x 1023
F = (9/5)(C) + 32C = 5/9 (F – 32)K = C + 273
1. Which of the following would be classified as a homogeneous mixture?
a) a gold barb) pure distilled water
c) sugar dissolved in waterd) iodine crystals
c. a and d are elements, b a pure compound
2. Which of the following would be equivalent to 65 nm?
a) 65 x 109 mb) 65,000 pm
c) 65 Åd) 6.5 x 10-2 cm
b. there are 1000 pm in 1 nm
3. Which of the following numbers contains 4 significant figures?
a) 7.5 x 104b) 2.300 x 10-6
c) 4.00268d) 0.003
b. d contains only 1 sig fig since the three zeroes are just place-holders
4. An individual suffering from high cholesterol has 305 mg of cholesterol per 100 mL of blood. If the total blood volume of this person is 5.8 L, how much total blood cholesterol does the person contain?
a) 0.203 gb) 17.7 g
c) 17,700 gd) 3.05 g
305 mg x 5800 mL = 17,700 mg = 17.7 g
100 mL
5. The density of Ru metal is 12.4 g/mL. What will be the mass of a block of Ru metal that measures 0.25 m x 0.25 m x 0.50 m?
a) 0.031gb) 400 g
c) 388 kgd) 2520 kg
12.4 g/cm3 x 25 cm x 25 cm x 50 cm = 387,500 g = 388 kg
6. A recent very cold morning in Logan found temperatures of -25° F. Which of the following expresses this same temperature in another scale?
a) -32° Cb) -4° C
c) 248 Kd) -25 K
(-25-32) x 5/9 = -32 C
7. How many hydrogen atoms are present in a molecule of (NH4)2HPO4?
a) 4b) 8
c) 1*d) 9
8. What is the correct name of Mg(ClO2)2?
a) magnesium chlorateb) manganese hypochlorite
*c) magnesium chlorited) magnesium perchlorane
e) Mango Chloe
9. What is the most likely formula of a compound composed of Ca and I ions?
a) CaIb) Ca2I
*c) CaI2d) Ca2I2
Ca has a charge of +2, I has a charge of -1
10. Glucose has a molecular formula of C6H12O6. What is its correct empirical formula?
a) CHOb) C6H12O6
*c) CH2Od) CH6O
11. Consider an atom represented as 80Br. What is the correct number of particles contained in this atom?
a) 80 protons, 80 neutrons, 80 electrons
b) 35 protons, 80 neutrons, 35 electrons
c) 35 protons, 35 neutrons, 45 electrons
*d) 35 protons, 45 neutrons, 35 electrons
e) 80 fignewtons, 45 croutons, 80 enrons
12. An entity contains 37 protons, 48 neutrons, and 36 electrons. Which would be its correct designation?
*a) 85Rb+b) 48Cd-
c) 48Rbd) 37Cd+
the superscript is the combined number of protons and neutrons. charge is difference between protons and electrons
13. When the following equation is balanced, what subscript b will be written in front of H2O?
a La2O3 + b H2O --> c La(OH)3
a) 1*b) 3
c) 4d) 6
1 La2O3 + 3 H2O --> 2 La(OH)3
14. Two isotopes of copper occur naturally. They have masses 62.930 and 64.928. Given that the average atomic mass of copper is 63.546, what is the natural abundance of the two isotopes?
a) 62.9% mass=62.930, 37.1% mass=64.928
*b) 69.2% mass=62.930, 30.8% mass=64.928
c) 50.0% mass=62.930, 50.0% mass=64.928
d) 96.9% mass=62.930, 3.1% mass=64.928
x (62.930) + (1-x)( 64.928) = 63.546
x = 0.692
15. What is the correct formula weight of Al(OH)3?
a) 44b) 27
c) 46*d) 78
27 + 3(16+1) = 78
16. What is the percentage carbon by weight in C2H5OH?
a) 52%b) 26%
c) 22%d) 78%
12x2 = 0.52
46
17. How many Sc atoms are present in 90 g of this element?
a) 2b) 6.02 x 1023
c) 45d) 1.2 x 1024
90 g of Sc = 2 moles. each mole contains 6.02 x 1023 atoms
18. How many moles of benzene (C6H6) are present in 3.9 g?
a) 23.4 x 1023b) 78
*c) 0.05d) 3.9
MW of benzene = 78. 3.9/78 = 0.05
19. A material is analyzed and found to contain 63.4% Mn by weight, and 36.6% O. What is its empirical formula?
*a) MnO2b) Mn2O
c) Mn5O3d) MnO4
Mn: 63.4/55=1.15 O: 36.6/16=2.29 2.29/1.15 ~ 2
20. A substance has empirical formula CH2, and molar mass of 42. What is the correct molecular formula?
a) CH2b) C2H4
c) C4H8*d) C3H6
42/14 = 3
21. The complete combustion of octane proceeds by the equation
2 C8H18 + 25 O2 --> 16 CO2 + 18 H2O
How much O2 is needed to completely burn 57 g of C8H18?
a) 1425 gb) 114 g
*c) 200 gd) 57 g
e) an awful lot
(57g/114 g/mole) x 25/2 x 32 g/mole
22. Which of the following is most likely to be insoluble in water?
a) NaOH*b) CaCO3
c) AgNO3d) (NH4)2SO4
23. What is the oxidation number of the element C in Na2CO3?
a) +1b) +5
*c) +4d) +3
Na +1, O -2, so C must be +4 to make total sum to 0
24. Which element is oxidized in the following reaction?
Fe2O3 + 3 CO --> 2 Fe + 3 CO2
a) Fe*b) C
c) Od) nothing is oxidized
oxidation state of C changes from +2 in CO to +4 in CO2
25. How many moles of KMnO4 are present in 50 mL of a 0.12 M solution?
a) 0.6b) 0.006
c) 0.05d) 1.2
0.12 mole/L x 0.050 L = 0.006 moles