Chem 121: Midterm Practice Exam
Spring 2009
Name:______
Multiple Choice (1 pt each)
1)5.21 cm is the same distance as
A) 0.0521 m.
B) 52.1 dm.
C) 5.21 mm.
D) 0.00521 km.
E) 5210 m.
2)The amount of space occupied by a substance is its
A) mass.
B) density.
C) weight.
D) length.
E) volume.
3)The measurement 0.000 0043 m, expressed correctly using scientific notation, is
A) 4.3 x 10-7 m.
B) 4.3 x 10-6 m.
C) 4.3 x 106 m.
D) 0.43 x 10-5 m.
E) 4.3 m.
4)The mass number of an atom can be calculated from
A) the number of electrons.
B) the number of protons plus neutrons.
C) the number of protons.
D) the number of electrons plus protons.
E) the number of neutrons.
5)Consider a neutral atom with 30 protons and 34 neutrons. The number of electrons in this atom is
A) 30.
B) 32.
C) 34.
D) 64.
E) 94.
6)The elements lithium, sodium, and potassium
A) are isotopes of each other.
B) are in the same period of elements.
C) have the same number of neutrons.
D) are in the same group.
E) have the same mass number.
7)What is the electron configuration for aluminum?
A) 1s22s22p63s23p1
B) 1s22s22 p63s23p3
C) 1s22s22 p63s23p5
D) 1s22s22 p63s23p6
E) 1s22s22 p63s23p8
8)How many electrons will aluminum gain or lose when it forms an ion?
A) lose 1
B) gain 5
C) lose 2
D) lose 3
E) gain 1
9)The compound MgCl2 is named
A) magnesium chlorine.
B) magnesium dichloride.
C) magnesium (II) chloride.
D) magnesium chloride.
E) dimagnesium chloride.
10)The formula for a molecule formed from N and Cl would be
A) NCl.
B) NCl2.
C) NCl3.
D) N3Cl.
E) NCl5.
11)The correct name for the compound N2O3 is
A) nitrogen oxide.
B) nitrogen trioxide.
C) dinitride trioxide.
D) dinitrogen oxide.
E) dinitrogen trioxide.
12)The name of Al2(SO4)3 is
A) aluminum(III) sulfate.
B) dialuminum trisulfate.
C) dialuminum sulfate.
D) dialuminum trisulfide.
E) aluminum sulfate.
13) What coefficient is placed in front of O2 to complete the balancing of the following equation?
C5H8 + ? O2 → 5CO2 + 4H2O
A) 1
B) 3
C) 5
D) 7
14)In the following reaction, what is the correct coefficient for aluminum chloride?
Al(s) + Cl2 (g) → AlCl3 (s)
A) 1 (this is can also be correct)
B) 2 (this is how we did it in class)
C) 3
D) 4
15)0.100 mole of lithium weighs
A) 3.00 g.
B) 0.300 g.
C) 6.94 g.
D) 0.694 g.
Chapter 1:
Round each number to 3 significant figures: (1 pt each)
43.5672
43.6
0.00023387
0.000234
Write each number in scientific notation: (1 pt each)
456.3
4.563x102
0.00077
7.7x10-4
Ethanol has a density of 0.79 g/mL. How many pounds does 2.00 gallons of ethanol weigh? (4 pts)
13. lb
Chapter 2:
A neutral atom has 8 protons and 8 neutrons: (1 pt each)
-What is the mass number?
16
-How many electrons does this element have?
8
-What is the atomic number?
8
-What Element is this?
Oxygen
-Is the atomic size Larger or Smaller than Boron?
smaller
-Is the atomic size Larger or Smaller than Sulfur?
smaller
-What is the electron configuration? 1s22s22p4
-How many valence electrons?
6
-Write the electron dot symbol for this atom
Chapter 4:
Consider the compound formed when Phosphorus and Bromine bond. Answer the following questions:
(2pts each)
-Write the chemical formula for this compound
PBr3
-What is the name of this compound?
Phosphorus Tribromide
-Draw the electron dot structure of this compound
See in class
-What is the geometry of this compound? Draw the 3d structure the best you can
See in class
-Overall is this compound polar or non-polar? Draw the dipoles that form from each bond and if the molecule is polar draw the Net Dipole of the molecule.
Polar
Chapter 5:
Acetylene gas, C2H2, reacts with oxygen according to the following equation. If 12.0 grams of acetylene react completely with sufficient oxygen, how many grams of carbon dioxide are produced? (8 pts)
2C2H2 + 5O2 → 4CO2 + 2H2O
40.6 g CO2
How many Liters are produced? (2pts)
20.7 L CO2