Unit 4 Regular Lecture File
Problem
1. Determine the mass in grams of 5.00 mol of oxygen. The molar mass of oxygen is 16.00 g/mol.
2. Determine the number of moles of helium in 10.0 g of helium. The molar mass of helium is 4.00 g/mol.
3. The mass of 1 mol of gold atoms is 196.97 g. Find the mass of 1 atom of gold.
4. How many moles of iron are equivalent to 1.11  1025 atoms?
5. How many atoms are present in 8.00 mol of chlorine atoms?
6. How many atoms are present in 80.0 mol of zirconium?
7. How many moles of platinum are equivalent to 1.20  1024 atoms?
8. Determine the number of moles in 100. g of potassium. The molar mass of potassium is 39.10 g/mol.
9. Determine the mass in grams of 10.0 mol of bromine. The molar mass of bromine is 79.90 g/mol.
Short Answer
10. In terms of the periodic law, explain which two of these elements are most similar: sodium (element 11),
phosphorus (element 15), and sulfur (element 16).
11. What can you predict about the properties of xenon and helium, both in Group 18 in the periodic table? Why?
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____ 12. The mass of two moles of oxygen atoms (atomic mass 16 amu) is
a. 32 g.
c. 16 g.
b. 48 g.
d. 64 g.
____ 13. If 6 g of element K combine with 17 g of element L, how many grams of element K combine with 85 g of
element L?
a. 17 g
c. 91 g
b. 30 g
d. 23 g
____ 14. A prospector finds 39.39 g of gold (atomic mass 196.9665 amu). She has
a. 6.02  1023 atoms.
c. 4.30  1023 atoms.
b. 2.30  1023 atoms.
d. 1.20  1023 atoms.
____ 15. The mass of exactly 5 mol of cesium (atomic mass 132.9 amu) is
a. 664.5 g.
c. 6.02  1023 g.
b. 5 g.
d. 132.9 g.
____ 16. How many moles of atoms are in 50.15 g of mercury (atomic mass 200.59 amu)?
a. 0.2500 mol
c. 0.1001 mol
b. 0.1504 mol
d. 0.4000 mol
____ 17. In determining atomic mass units, the standard is the
a. O-16 atom.
c. H-1 atom.
b. C-12 atom.
d. C-14 atom.
____ 18. The molar mass of NH3 is 17.03 g/mol. How many moles of NH3 are present in 107.1 g?
a. 6.289 mol
c. 3.614 mol
b. 107.1 mol
d. 0.1623 mol
____ 19. The elements that border the zigzag line in the periodic table are
a. inactive.
c. metals.
b. metalloids.
d. nonmetals.
____ 20. Bromine, atomic number 35, belongs to Group 17. How many electrons does bromine have in its outermost
energy level?
a. 35
c. 17
b. 7
d. 18
____ 21. Isotopes are atoms of the same element that have different
a. numbers of protons.
c. masses.
b. numbers of electrons.
d. principal chemical properties.
____ 22. The forces that hold the particles in the nucleus together are called
a. gravitational forces.
c. magnetic forces.
b. electron clouds.
d. nuclear forces.
____ 23. What is the percentage composition of CO?
a. 43% C, 57% O
c. 12% C, 88% O
b. 50% C, 50% O
d. 25% C, 75% O
____ 24. What is the formula mass of (NH4)2SO4?
a. 118.34 amu
c. 132.13 amu
b. 128.06 amu
d. 114.09 amu
____ 25. Who discovered the nucleus by bombarding gold foil with positively charged particles and noting that some
particles were widely deflected?
a. Rutherford
c. Chadwick
b. Dalton
d. Bohr
____ 26. Argon, krypton, and xenon are
a. actinides.
c. noble gases.
b. lanthanides.
d. alkaline earth metals.
____ 27. Balance the following equation:
 _____ +
a.
c.
b.
d.
____ 28. What is the percentage composition of CF4?
a. 20% C, 80% F
c. 16.8% C, 83.2% F
b. 81% C, 19% F
d. 13.6% C, 86.4% F
2
2
3
____ 29. Nitrogen's electron configuration is 1s 2s 2p . To what group does nitrogen belong?
a. Group 15
c. Group 2
b. Group 7
d. Group 17
____ 30. The element that has the greatest electronegativity is
a. chlorine.
c. sodium.
b. oxygen.
d. fluorine.
____ 31. Isotopes of an element contain different numbers of
a. protons.
c. electrons.
b. nuclides.
d. neutrons.
____ 32. The molar mass of H2O is 18.015 g/mol. How many grams of H2O are present in 0.20 mol?
____ 33.
____ 34.
____ 35.
____ 36.
____ 37.
____ 38.
____ 39.
____ 40.
____ 41.
____ 42.
____ 43.
____ 44.
____ 45.
____ 46.
a. 0.2 g
c. 3.6 g
b. 89.9 g
d. 35.9 g
What is the formula mass of magnesium chloride, MgCl2?
a. 46 amu
c. 59.763 amu
b. 106.354 amu
d. 95.211 amu
A positive ion is known as a(n)
a. anion
c. valence electron.
b. cation.
d. ionic radius.
A sample of tin (atomic mass 118.69 amu) contains 3.01  1023 atoms. The mass of the sample is
a. 59.3 g.
c. 3.01 g.
b. 11 g.
d. 72.6 g.
What is the number of moles of chemical units represented by 9.03  1024 units?
a. 9.03 mol
c. 1.50 mol
b. 15.0 mol
d. 10.0 mol
The mass of 1 mol of chromium (atomic mass 51.996 amu) is
a. 51.996 g.
c. 12 g.
b. 6.02  1023 g.
d. 198 g.
Valence electrons are those
a. in the lowest energy level.
c. closest to the nucleus.
b. in the highest energy level.
d. combined with protons.
What is the percentage composition of oxygen in H2O?
a. 33%
c. 88.8%
b. 15.99%
d. 99.8%
The mass of a sample of nickel (atomic mass 58.69 amu) is 176.07 g. It contains
a. 5.869  1024 atoms.
c. 1.7607  1024 atoms.
b. 5.869  1023 atoms.
d. 1.806  1024 atoms.
Chlorine has atomic number 17 and mass number 35. It has
a. 17 protons, 17 electrons, and 18 neutrons.
b. 35 protons, 35 electrons, and 17 neutrons.
c. 17 protons, 17 electrons, and 52 neutrons.
d. 18 protons, 18 electrons, and 17 neutrons.
The mass of a sample of nickel (atomic mass 58.69 amu) is 11.74 g. It contains
a. 1.869  1023 atoms.
c. 1.174  1023 atoms.
b. 3.256  1023 atoms.
d. 1.205  1023 atoms.
In Group 2 elements, the valence electrons are in sublevel
a. d.
c. p.
b. s.
d. f.
What is the percentage composition of CuCl2?
a. 33% Cu, 66% Cl
c. 65.50% Cu, 34.50% Cl
b. 50% Cu, 50% Cl
d. 47.263% Cu, 52.737% Cl
According to Dalton's atomic theory, atoms
a. of each element are identical in size, mass, and other properties.
b. of different elements cannot combine.
c. are destroyed in chemical reactions.
d. can be divided.
The mass of 2.50 mol of calcium atoms (atomic mass 40.08 amu) is approximately
a. 10.0 g.
c. 42.5 g.
b. 100 g.
d. 250 g.
____ 47. The molar mass of CCl4 is 153.81 g/mol. How many grams of CCl4 are needed to have 5.000 mol?
a. 769.0 g
c. 30.76 g
b. 796.05 g
d. 5 g
____ 48. Ionization energy is the energy required to remove ____ from an atom of an element.
a. an electron
c. the electron cloud
b. the nucleus
d. an ion
____ 49. A mass of 6.005 g of carbon (atomic mass 12.010 amu) contains
a. 0.5000 mol C.
c. 1 atom O.
b. 2 atoms C.
d. 1 mol C.
____ 50. A quantity of sodium (atomic mass 22.99 amu) contains 6.02  1023 atoms. The mass of the sodium is
a. 6.02  1023 g.
c. 22.99 g.
b. not determinable.
d. 3.88 g.
____ 51. A negative ion is known as a(n)
a. ionic radius.
c. cation.
b. anion.
d. valence electron.
____ 52. The mass of a sample containing 3.5 mol of silicon atoms (atomic mass 28.0855 amu) is
a. 72 g.
c. 98 g.
b. 28 g.
d. 35 g.