Chem. 110
Summer 2014
Name _______________________________
EXAM 2
(Last)
(First)
1. Complete the following table. Assume all atoms are neutral unless specified (9 points)
Element
Element
nuclear
symbol
Number of
Neutrons
Number of
electrons
Number of
protons
22
16
Mass
Number
40
14
Strontium-90
81
35Br
2.
3.
Write the nuclear symbol for the an Iron atom that has 87 subatomic particles (3 points)
Write the nuclear symbol for an isotope of chlorine that contains the same number of neutrons
as silicon-phosphorous-32. (3 points)
______________________________
Is the following compound ionic or molecular? (4 points)
NH4OH _________________
NiCl2 _________________
/19 points
1
HNO3 ____________________
PBr3__________________
4. Write the formula for each of the following (5 points)
a. chloric acid
_________________________
b. aluminum dihydrogen phosphate
_________________________
c. zinc acetate
_________________________
d. silver bisulfite
_________________________
e. ferric nitrite
_________________________
/10pts.
1. Write the Name for each of the following (5 points)
2
a. (NH4)2C2O4
_________________________
b. S3N2
_________________________
c. CrI3
_________________________
d. BaCrO4
_________________________
e. H2SO4(aq)
_________________________
Problems
For each of the following problems give the complete setups including all units. Use
dimensional analysis when possible. Present your work in a neat and organized manner. If work is
not shown, NO CREDIT will be given for your answer.
1. How many atoms of oxygen are there in 2.453 grams of aluminum sulfite? (8 points)
Answer: ________________________
2. What is the total number of atoms in 1.50 X 104 grams of caffeine C8H10N4O2 ?
(molar mass C8H10N4O2 = 194 g/mole) (8 points)
Answer: ________________________
3. How many grams of oxygen are in a sample of aspirin (acetylsalicylic acid C9H8O4 )that
contains 2.56 grams of hydrogen. (molar mass = 180.16 g/mole)? (8 points)
Answer: ________________________
4. How many grams of nitrogen are in 4.369 x 10 18 molecules of nitroglycerine, C3H5O9N3?
(molar mass C3H5O9N3 = 467.3075 g/mole)? (8 points)
Answer: ________________________
/32pts.
3
5. A 18.65 gram sample of copper metal is burned in a nitrogen atmosphere to produce 21.39 g of
a copper-nitrogen compound. Determine the compound’s empirical formula. (11 points) (This
is similar to what you did in the magnesium oxide lab.)
Answer: ________________________
6. What is the mass in grams of one single carbon monoxide molecule? (10 points)
Answer:__________________________
/21pts.
4
7.
(14 points) A 0.8640 gram sample of the compound responsible for the pungent odor of rancid
butter containing only H, C, and O is burned in a combustion analysis apparatus. The mass of
CO2 produced is 1.727 g, and the mass of water produced is 0.7068 g. What is the empirical
formula of the compound?
Answer: ________________________
8. If a compound with the empirical formula C5H10O2 has a molar mass of 408.5 g/mole, what is
the molecular formula of the compound? (6 points)
Answer: ________________________
/20pts.
5