Exam 1 Review Chem 110 MJ Bojan
CHEM 110 EXAM Exam 1 Mon. Feb. 4
6:30-7:45pm
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Exam 1 Review
CHEM 110 EXAM Exam 1 Mon. Feb. 4
6:30-7:45pm
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Regular Conflict 4:40-5:55 pm 101 Thomas
! Covers: Lectures 1-12 ! Chapters 1-4, 5.1-2,5.5 and 6
Format: 28 Multiple Choice questions
See sample practice exams in your packet or on the Chem 110 Web page: select Handouts.
Exam 1 Review
Atomic structure
Magnesium has only three naturally occurring isotopes: 24Mg with a mass of 23.985 amu abundance of (78.99%), 25Mg with a mass of 24.986 amu (10.00%), and xMg with an unknown atomic weight. What is the x in xMg?
Exam 1 Review
Introduction to energy
! First Law of thermodynamics: conservation of energy
! ΔE = q+w (sign of energy)
! Electrostatic interactions
! Light behaves as a wave: electromagnetic spectrum
! Particle nature of light: Energy of photon
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What is the sign of ΔE?
w w
q q
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1 2
Conservation of energy Two gas, labeled A and B, have been sealed in two separate containers. The containers are connected by a double piston that has been designed so that an expansion of one gas will cause the compression of the other gas. A process occurs in gas A that causes 50 kJ of heat to be released into the surroundings and reduces the internal energy of gas A by 100 kJ. This process also causes the piston to move and 20 kJ of heat is observed being released from gas B into the surroundings. What is the change in internal energy of gas B?
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0 d 2d 3d 4d
Electrostatic Interactions
+1
+2
-2
-1
+2
+3 I
II
III
Put these in order of increasing electrostatic potential energy.
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Photon energy
What is the energy of one mole of photons of green light of λ = 500 nm?
A. 3.98 ! 10－19J
B. 2.39 ! 10－4J
C. 239 kJ
D. 2.39 ! 10－13J
E. None of the above answers is within ± 10% of the correct answer
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Particle nature of light
A hair dryer emits 2500 J of 3972 nm radiation in 1 second. How many moles of photons does the hair dryer emit in 100 seconds?
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Structure of atom
! Where are the electrons?
! What is the energy of the electron?
! Structure: equal electron configuration
! Quantum numbers can tell us structure (and energy).
! How do electron configurations give information about energy?
Practice making connections
Exam 1 Review
What is the energy of the electron?
In the Bohr model, which electronic transition absorbs the shortest wavelength of light?
A. n = 10 → n = 2
B. n = 2 → n = 1
C. n = 2 → n = 10
D. n = 1 → n = 2
E. n = 2 → n = 3
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Connecting QN to energy
An electron has the quantum numbers n = 3, != 2, m! = +1.
Which one of the following orbitals can contain an electron that has the same energy as this electron? A. 2s B. 3s C. 4p D. 3d E. 4d
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Structure: equal electron configuration
All of the electron configurations given below correspond to iron. Which one of the following statements concerning these electron configurations is false?
I [Ar] 4s2 3d6
II [Ar] 3d6
III [Ar] 3d5
IV [Ar] 3d8
A. I is the ground state electron configuration of iron.
B. II is the ground state electron configuration of Fe+2
C. III is the ground state electron configuration of Fe+3
D. IV is an excited state electron configuration of Fe.
E. There are no unpaired electrons in configuration I. Exam 1 Review
How do electron configurations give information about energy?
Which orbital represents the highest energy orbital for oxygen with the excited state electron configuration, 1s22s22p33p1?
A.
E. None of the above.
D.B. C.
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Properties of atoms
Which of the following is a true statement:
A. More energy is consumed when Cl accepts an electron than F accepts an electron.
B. Less energy is needed to ionize Ca than Mg.
C. Energy is released when Na is ionized to Na+.
D. B is easier to ionize than K.
E. F+ is more stable than F－.
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Properties of atoms What is the correct order of these ions, from largest to smallest?
S2－ Se2－ Li+ As3－ Na+
A. As3－ > Se2－ > S2－ > Na+ > Li+
B. Li+ = Na+ > S2－ > Se2－ > As3－
C. Na+ > Li+ > As3－ > Se2－ > S2－
D. Se2－ > As3－ > Na+ > S2－ > Li+
E. Li+ > Na+ > Se2－ > S2－ > As3－
Exam 1 Review
Below are the successive ionization energies of an atom. Which one of the following atoms do these
energies belong to?
I1 = 578kJ I2 = 1820kJ I3 = 2750kJ I4 = 11,600kJ
A. Al
B. S
C. Li
D. Mg
E. Ne
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Atoms combine to form molecules
! What is a molecular formula?
! What does a molecular formula tell you?
! What is an empirical formula?
! How do you determine the empirical formula from % composition?
Practice making connections
Exam 1 Review
Which of the following samples contains the largest number of atoms?
A. 0.5 mole of ethene (C2H4)
B. Avogadro's number of lithium hydride (LiH) molecules
C. 56.8 g of diphosphorous pentoxide (P2O5)
D. 0.9 mole of water (H2O)
E. 1.5 ! 1024 atoms of argon (Ar)
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Polyurethane insulators can be formed using the diisocyanate shown below. What is the empirical
formula of the diisocyanate shown?
A. C8H4O2N2
B. C4H4O1N1
C. C4H2O1N1
D. C4H5O1N1
E. C8H8O2N2
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Molecular formulas
Alum used in cooking is a hydrate of potassium aluminum sulfate KAl(SO4)2 ! x H2O.
If 4.74 g of alum is heated, the dehydrated compound that remains weighs 2.58g. What is the value of x in the formula for alum?
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Atoms form bonds
! Ionic bonds ! What is ionic, what is covalent?
! Naming ionic compounds (including polyatomic ions)
! Lattice Energy: measure of the strength of ionic bond
! Covalent bonds ! Trends in bond length and strength
! Bond order
! Electronegativity
! Bond polarity
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Which of the following oxides is an ionic compound?
A. XeO3
B. Y2O3
C. SO2
D. N2O
E. P2O5
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Lattice Energy
MgO has a higher melting point than KCl. Which of the following reasons support this fact?
1. MgO has a smaller lattice energy than KCl, and therefore it melts at a higher temperature.
2. The magnesium ion is larger than the potassium ion, and therefore the lattice energy of MgO is higher.
3. Magnesium ion has a larger charge than the potassium ion, and therefore the lattice energy of MgO is higher.
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Bond strength
Which one of the following has the strongest H －X bond?
A. H－Cl
B. H－Br
C. H－F
D. H－I
E. H－S－H
Exam 1 Review
Bond polarity
Rank the following in order of increasing polarity. 1. Cl － Cl 2. K － F 3. C － F 4. C － O
A. Cl － Cl < K －F < C － F < C － O
B. Cl － Cl < C － F < C － O < K － F
C. Cl － Cl < C － O < C － F < K － F
D. K －F < Cl － Cl < C － O < C － F
E. C － O < C － F < K － F < Cl － Cl
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