First Semester Practice Problems
1. What is the answer with the correct number of significant figures for these problems?
a. 3.900 + .0789
b. 4.511 - 2.3
c. 0.00777 x 340
d. 5401/2220
3.979
2.2
2.6
2.43
2. How many significant figures in these numbers?
a. 4.570
b. 6700
c. 0.0098
d. 0.0980
4
2
2
3
3. How much energy is required to raise the temperature of an 225g aluminum pan from room
temperature (32C) to 100C? The heat capacity of aluminum is 0.900 J/gC.
13770 J
4. What is the mass of a silver pot if 1575 J of energy raises its temperature 150C? The heat
capacity of silver is 0.235 J/gC.
m = 44.7 g
5. Fill in the blanks in the following table:
Isotope
Mass #
Atomic #
symbol
52
Cr24
52
24
197
Au79
197
79
122
Cd48
122
48
#protons
#neutrons
#electrons
24
79
48
28
118
74
24
79
48
6. Determine the molar mass of these compounds:
a. MgBr2
b. Fe(ClO2)3
c. Al2(CO3)3
184.13g
258.20g
233.99g
7. Determine the percent composition of Mg(NO3)2.
16.3% Mg
18.89% N
64.72% O
8. What is the empirical formula of a compound composed of 88.5% B and 11.5% H?
B5H7
9. What is the empirical formula of a compound composed of 92.26% C and 7.74% H?
CH
10. Convert to moles:
a. 56.7 g H2O
b. 301 g Mg(NO2)2
c. 0.667 g MgBr2
3.15 mol
2.03 mol
00.362 mole
11. Convert to grams
a. 1.33 mol H2O
b. 0.977 mol Mg(NO2)2
c. 22 mol MgBr2
24.0 g
145 g
4100 g
12. Convert 1345 cm to km.
0.01345 km
13. Convert 0.0644 kg to mg.
64400 mg
14. List the discovery each man is credited with making:
a. Rutherford
nucleus with protons using gold foil experiment b. Thomson electron
c. Bohr electrons reside in energy levelsd. Dalton First atomic theory (know the planks)
15. Iridium has two isotopes. Ir-191 has an abundance of 37.30% and Ir-193 has an abundance of
62.70%. What is the average atomic mass of iridium?
192.25 amu
16. Name the following ionic compounds:
NaBr: sodium bromide
Mn(NO3)2 manganese (II) nitrate
PbSO4 lead (II) sulfate
Al3(CO3)3 aluminum carbonate
C2S4
PBr3
CCl4
B2O5
17. Give the formula for these ionic compounds:
copper (II) hydroxide Cu(OH)2
magnesium chloride MgCl2
aluminum nitrite Al(NO3)3
calcium phosphate Ca3(PO4)2
dihydrogen monoxide
carbon dioxide
diphosphorous pentoxide
18. Identify the correct periodic table family. Answers will be used more than once.
alkali metals, alkaline earth metals, transition metals, rare earth metals, metalloids, nonmetals, halogens,
noble gases
metalloids semi-conductors
alkali
explosive in water
noble gases 8 valence shell electrons
rare earth
noble gases
most difficult to extract from ores
lowest melting and boiling points
trans/rare
high melting and boiling
points
noble gases gases at room temperature
nonmetals
form organic compounds
alkali metal soft metals
alkaline earth
two valence shell electrons
halogens
members in all three states of matter at room temperature.
nonmetals “elements of life”
alkali
metals with lowest densities
three fams never found uncombined in nature
rare earth
some members are radioactive
alkali
most reactive metals
noble gases
non-reactive
alkaline earth
form +2 ions
transition metals ductile and malleable
alkali
1 valence shell electron
rare earth metals thorium is a member of this
group
transition
vanadium is a member of this group nonmetals
alkali
potassium is a member
halogens
iodine is a member
trans/rare
sulfur is a member of this group
noble gases
krypton is a member
transition metals conductors of heat and electricity
members may form ions of different charges
19. Determine the electron configuration for the following atoms:
Mg: 1s22s22p63s2
Mn: 1s22s22p63s23p64s23d5
Pb: 1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p2
How many valence shell electrons will be in each of the following Lewis dot structures?
PBr3
CO32CCl4
NH4+