Chemistry Exam
Electron
-1 Charge smallest mass of the three particles particle labeled "C" (Outside the nucleus)
Suppose the half-life of a material is 10 days. You have one 1kg of the material today. How much of the material would you have after 10 days and 20 days, respectively?
0.5 kg after 10 days, and 0.25 kg after 20 days
How many electrons are transferred between the cation and anion to form the ionic bond in one formula unit of each compound?
1 electron-LiBr, KCl, KF 2electrons-BaO, CaS
Consider a covalent compound that is composed of a nitrogen atom (N), a hydrogen atom (H), and a carbon atom (C). How many electrons should the electron-dot structure of the covalent compound contain?
10
Which of the following nuclei is likely to release energy when undergoing nuclear fusion?
2/1H (deuterium)
Which of the following nuclei could be used in a nuclear fission power plant?
235/92U (Uranium-235)
The nucleus of an electrically neutral iron atom contains 26 protons. How many electrons does this iron atom have?
26
Identify the oxidizing agent and the reducing agent in each reaction below.
2Al(s) is the reducing agent and 3Cl2(g) is the oxidizing agent that yields to 2AlCl3(s) O2(g) is the oxidizing agent and 2Mg(s) is the reducing agent that yields to 2MgO(s)
How many different types of molecules are shown together in the three boxes?
3
A material has a half-life of 1 day. If 2 kg of this material is available today, how much of it was available yesterday, and how much the day before?
4 kg yesterday, and 8 kg the day before.
What is the half-life of uranium-238?
4.5 billion years
What is a mixture?
A combination of two or more substances in which each substance retains its individual chemical properties.
How does a chemist define a "pure" material?
A material consisting of only one element or compound.
What is released in the formation of a condensation polymer?
A small molecule is released.
Classify these compounds as a Brønsted-Lowry acid, a Brønsted-Lowry base, or neither.
Acid: HBr, HCl, H3PO4 Base: KOH, CH3NH2 Neither: CH2Cl2, CH3CHO
If a pair of carbon nuclei were fused and the product emitted a beta particle, what element would be produced?
Al
Identify the functional group(s) present in each molecule.
Alcohol: CH3CH2CH2CH2OH Ketone: CH3COCH2CH2CH2CH3 Carboxylic acid: CH3CH2CH2COOH
Identify each property as that of alcohols, ethers, or both.
Alcohols: can hydrogen-bond with each other, boiling point much higher than alkanes Ethers: boiling point close to that of alkanes Both: contain oxygen, can hydrogen-bond with water, have flammable vapors
What change in atomic number occurs when a nucleus emits an alpha particle? What change occurs when the nucleus emits a beta particle?
Alpha emission DECREASES atomic number by 2, while beta emission INCREASES it by 1.
Which type of radiation-alpha, beta, or gamma- results in the greatest change in mass number? Which results in the greatest change in atomic number?
Alpha radiation results in the greatest change in mass number and atomic number.
The polymer styrene-butadiene rubber (SBR), shown, is used for making tires as well as bubble gum. Is it an addition polymer of a condensation polymer?
An addition polymer
How does an ion differ from an atom?
An atom with a net electric charge is an ion.
Why do we say atomic spectra are like fingerprints of the elements?
An atom's spectrum has unique characteristic patterns.
Distinguish between an atom and an element.
An element is made of only one type of atom.
Exothermic reactions are favored because they release heat to the environment. Would an exothermic reaction be more favored or less favored if it were carried out within a superheated chamber?
An exothermic reaction would be less favored if it were carried out within a superheated chamber.
Proton
Approximately the same mass as a neutron +1 charge particle labeled "B" (Red in the nucleus)
What role does the atomic number play in the periodic table?
Atoms in the periodic table are ordered by increasing atomic number
What is the name of the ionic compound BaCO3?
Barium carbonate
Do amines tend to be acidic, neutral, or basic?
Basic
Why is the rusting of iron considered to be a chemical change?
Because iron can be made into objects that rust cannot be made into.
In each molecule, which atom carries the greater POSITIVE CHARGE: Br−F?
Bromine
What is one way functional groups are distinguished from one another?
By the heteroatoms they contain.
Which is heavier: a water molecule, H2O, or a carbon dioxide molecule, CO2?
CO2, Carbon dioxide molecule
Determine what occurs at each electrode in the electrolysis of molten sodium chloride, NaCl.
Chloride ions are consumed at the anode. Chlorine gas is produced at the anode. Sodium ions are consumed at the cathode. Sodium metal is produced at the cathode.
What is the atomic symbol for the element cobalt?
Co
Why don't all collisions between reactant molecules lead to product formation?
Collisions must have the correct orientation to lead to a product formation.
What actions will decrease the rates of the reactions in the food (and therefore slow down spoiling)?
Decrease the rate of reaction: Lower the water content in the food, store food in airtight containers, store food in the freezer after preparing it, and transport food in a refrigerated truck Doesn't decrease the rate of reaction: store food at a high oxygen concentration, place food in a water bath, and place food on a warm surface.
What intermolecular forces are present in each of the substances?
Dispersion forces only=C4H10, C3H8 Dispersion forces and dipole-dipole forces=CH3F Dispersion forces, dipole-dipole forces, and hydrogen bonding=HF, C6H5OH
Review the concept of electronegativity in the textbook, and rank the acidity of these molecules in order from strongest to weakest: (a) ammonia, NH3; (b) water, H2O; (c) methane, CH4.
Electronegativity increase as it goes up and as it moves right across the periodic table Strongest: Water, H2O Middle: Ammonia, NH3 Weakest: methane, CH4
Review the concept of electronegativity in the textbook, and rank these elements from the weakest to strongest oxidizing agent: (a) nitrogen, N; (b) fluorine, F; (c) silicon, Si.
Electronegativity increases as you move up and right across the periodic table. Weakest: Silicon Middle: Nitrogen Strongest: Fluorine
Which electrons are most responsible for the properties of an atom?
Electrons in the outermost shell
Classify each of the following as an element, compound, homogenous mixture, or heterogenous mixture.
Element: oxygen and gold Compound: water and vitamin D Homogenous: saltwater and male syrup Heterogenous: fruit salad
Distinguish between an atom and an element
Elements are made of atoms (as well as molecules), and atoms are not made of elements
Which element within a compound is given first in the compound's name?
Elements to the left on the periodic table are given first in the compound's name
A scientist is studying how certain factors affect the rate of a particular reaction. She observes that under one set of conditions, the reaction proceeded much faster than under a different set of conditions. Identify the most likely sets of conditions that produced each reaction rate.
Faster reaction: higher temperature and larger quantities of reactants Slower reaction: lower temperature and smaller quantities of reactants.
Rank the following by speed
Fastest=Gamma particles Medium=beta particles Slowest=alpha particles The speed of the radioactive decay products is related to their mass: Heavier products move slower than lighter products
Which process would release energy from gold: fission or fusion?
Fission
What is the prime difference between a battery and a fuel cell?
Fuel cells continuously produce energy from fuel; batteries must be recharged or replaced.
Which process release energy from carbon: fission or fusion?
Fusion
Classify these elements by whether they get oxidized or reduced in the reactions shown here: 2Ca(s)+O2(g)→2CaO(s) F2(g)+2Li(s)→2LiF(s)
Gets Oxidized: Calcium and Lithium Gets reduced: Oxygen and Fluorine
(a) C-12, (b) C-14, and (c) N-14. From greatest to least, rank them by the number of neutrons in the nucleus.
Greatest=C-14 Middle=N-14 Least=C-12
(a) C-12, (b) C-14, and (c) N-14. From greatest to least, rank them by the number of nucleons in the nucleus.
Greatest=C-14 and N-14 Least=C-12
(a) C-12, (b) C-14, and (c) N-14. From greatest to least, rank them by the number of protons in the nucleus.
Greatest=N-14 Least=C-12 and C-14
What is the chemical formula for the compound dihydrogen sulfide?
H2S
The elements fluorine, chlorine, and bromine are also known as...
Halogens
Arrange the molecules in order of decreasing boiling point.
Highest-CH3OH Middle-HCl Lowest-H2
The average person in the United States is exposed to the following amount of radiations annually. Rank the following source of radiation in the increasing order of their ability to cause harm to living tissue. Weapons-test fallout=1 millirem Cosmic radiation=26 millirems Air (radon-222)=0.198 rems Diagnostic X rays=0.040 rems Television tubes=11 millirems Nuclear medicine=0.015 rems Ground=33 millirems
Highest= Air (radon-222)-0.198 rems Ground-33 millirems Cosmic radiation-26 millirems Television tubes-11 millirems Lowest= Weapons-test fallout-1 millirem
Rank these three types of radiation by their ability to penetrate a page of your book, form highest to lowest.
Highest=Gamma rays Middle=Beta particle Lowest=Alpha particle
Determine whether each of the following solutes is more soluble in hot water or cold water.
Hot water: sodium chloride and starch Cold water: carbon monoxide, nitrogen dioxide, and ozone
What are some of the clues that helps us to determine whether an observed change is physical or chemical?
If the appearance is restored when the original conditions are restored it was probably a physical change.
Distinguish between atomic number and mass number
In an atom, the ATOMIC NUMBER is the number of protons in the nucleus; the MASS NUMBER is the sum of the numbers of protons and neutrons.
Is a chain reaction more likely to occur in two separate pieces of uranium-235 or in the same two pieces stuck together?
It's more likely in two pieces stuck together.
Which have more neutrons than protons: large nuclei or small nuclei?
Large nuclei have more neutrons than protons.
Fluorine, Phosphorus, Neon: Rank from largest to smallest in terms of number of protons in the nucleus
Largest=Phosphorus Middle=Neon Smallest=Fluorine Because number of protons increase from top to bottom and from left to right The number of protons is the atomic number
Fluorine, Phosphorus, Neon: Rank from largest to smallest in terms of electrons
Largest=Phosphorus Middle=Neon Smallest=Fluorine Because the number of electrons increases from top to bottom and from left to right. The number of electrons is the atomic number
Rank from largest to smallest atomic radius
Largest=Polonium Tellurium Selenium Sulfur Smallest=Oxygen Because atomic radius increase from right to left and from top to bottom
Rank the following elements by atomic radius
Largest=Sodium Aluminum Silicon Sulfur Smallest=Argon Because atomic radius increases from right to left and from top to bottom
Rank the three subatomic particles in order of increasing mass: (a) neutron, (b) proton, and (c) electron.
Least mass=electron Middle mass=proton Most mass=neutron
Alpha particles
Least penetration Mass-4amu Charge=+2
Rank the following hydrocarbons in order of increasing number of hydrogen atoms.
Least: Cyclobutane=2-Butene (one double bond) Most: Butane (no double bonds)
Rank the following organic molecules in order of increasing solubility in water.
Least: No OH Middle: One OH Most: Two OH
Rank the compounds in order of increasing symmetry: (a) OF2, (b) CF4, (c) NF3
Least: OF2 Middle: NF3 Most: CF4
Rank these bonds in order of increasing polarity: (a) F-H, (b) S-H, (c) P-H.
Least: P-H Middle: S-H Most: F-H
Rank the following organic molecules in order of increasing solubility in water.
Least: Pentagon with O Middle: Pentagon with one N and one H Most: Pentagon with N+, 2 H's, and Cl-
Rank the solutions in order of increasing concentration of hydronium ions, H3O+: (a) hydrogen chloride, HCl (concentration = 2 M); (b) acetic acid, CH3COOH (concentration = 2 M); (c) ammonia, NH3 (concentration = 2 M).
Least: ammonia, NH3 Middle: Acetic acid, CH3COOH Most: Hydrogen chloride, HCl
Rank these covalent bonds in order of increasing bond strength: (a) C≡C, (b) C=C, (c) C−C.
Least: carbon single bond C Middle: carbon double bond B Most: carbon triple bond A
Rank the following reaction profiles in order of increasing reaction speed.
Least: low flat, hump up, high flat Middle: high flat, hump down, low flat Most: high flat, small dip down, low flat
Rank these compounds in order of increasing boiling point: (a) iodine, I2; (b) ammonia, NH3; (c) methane, CH4.
Least: methane, CH4 Middle: ammonia, NH3 Most: iodine, I2
Rank the following hydrocarbons in order of increasing number of hydrogen atoms.
Least: two double bonds Middle: One double bond Most: no double bonds
Rank the compounds in order of increasing numbers of atoms: (a) C12H22O12, (b) DNA, (c) Pb(C2H3O2)2.
Least= Pb(C2H3O2)2 Middle= C12H22O12 Most=DNA
Why is there more carbon-14 in living bones than in once-living ancient bones of the same mass?
Living organisms continuously add new carbon to bones, and new carbon contains radioactive carbon-14
How can you tell whether an atom within a compound takes on a positive or negative charge?
Locate the position of the atom in the periodic table
Beta particles
Medium penetration Mass-1/2000amu Charge=-1
Classify each description by the phase change it depicts.
Melting: a gold necklace is heated until it is liquefied Freezing: a cup of lemonade left outside solidifies & molten iron is cooled to make a cooking pan Evaporation: a pot of water on the stove comes to a boil & acetone sprayed in a whiteboard vaporizes Condensation: water droplets form on the windshield of a car on a cool morning
Are most elements metallic, nonmetallic, metalloid, or not yet confirmed?
Metallic
Name two physical properties of metals.
Metals can be drawn into wires and are opaque.
Magnesium ions carry a 2+ charge, and chloride ions carry a 1- charge. What is the chemical formula for the ionic compound magnesium chloride?
MgCl2
How can the components of a mixture be separated?
Mixtures can be separated using differences in their physical properties.
Are atoms made of molecules or are molecules made of atoms?
Molecules are made of atoms.
Rank the following atoms by number of valence electrons
More=Xenon Iodine Antimony Indium Fewer=Rubidium Because the row they are in determines the number of valences electrons (increases form left to right)
Rank the following isotopes in order of their radioactivity, from the most radioactive to the least radioactive: (a) nickel-59, half-life 75,000 years; (b) uranium-238, half-life 4.5 billion years; (c) actinium-225, half-life 10 days.
Most=Actinium-225, half life 10 days Middle=Nickel-59, half-life 75,000 years Least=Uranium-238, half-life 4.5 billion years Because the shorter the half-life the more radioactive the element is because it does not take as long to become radioactive
Consider three 1-g samples of matter: (a) carbon-12, (b) carbon-13, and (c) uranium-238. Rank them in terms of the number of atoms, from most to least.
Most=Carbon-12 Middle=Carbon-13 Least=Uranium-238
Ores of manganese, Mn, sometimes contain the mineral rhodochrosite, MnCO3, which is an ionic compound of manganese ions and carbonate ions. How many electrons has each manganese atom lost to make this compound?
N=2 electrons
What is the molecular formula for ammonium nitrate?
NH4NO3
A major source of chlorine gas, Cl2, is the electrolysis of brine, which is concentrated salt water, NaCl(aq). What other two products result from this electrolysis reaction?
NaOH and N2
Sort the following into naturally occurring and man-made sources of radiation.
Natural sources of radiation= Earth minerals, Cosmic radiation, and Air containing Radon-222 Man-made sources of radiation= Diagnostic X-rays, Television tube, and Nuclear medicine
Which process would release energy from iron: fission or fusion?
Neither fission nor fusion
Suppose 2 kg of a material has a half-life of one day. After how long will NONE of the material remain?
Never
Which heteroatom is characteristic of an amine?
Nitrogen
Oxygen, O2, has a boiling point of 90 K (-183C), and nitrogen, N2, has a boiling point of 77 K (-196C). Which is a liquid and which is a gas at 80 K (-193C)?
Nitrogen is a gas, oxygen is a liquid at 80 K
Is it possible to see an atom using visible light?
No
Neutron
No charge Particle labeled "A" (Blue in the nucleus)
Classify these descriptions as pertaining to nonspontaneous reaction in a cell only, a spontaneous reaction in a cell only, both, or neither.
Nonspontaneous cell: drives a nonspontaneous reaction, requires a battery Spontaneous cell: powered by a spontaneous reaction, is a battery Both: Oxidation occurs at the anode, reduction occurs at the cathode, electrons flow through a wire from anode to cathode Neither: Oxidation occurs at the cathode, reduction occurs at the anode, electrons flow though a wire from cathode to anode
Fusion only
Occurs on the sun Needs very high temperatures
Classify these molecules as polar or nonpolar.
Polar-CH3NH2, HF, H2S Nonpolar-BBr3, H2, CBr4
Which nonmetals could form an ionic compound with magnesium with the formula MgX2 (where x represents the nonmetal)?
Possible-F, Cl, Br Not possible-N, O, S
In a combustion reaction, ethanol (C2H5OH) is burned in the presence of oxygen (O2), producing carbon dioxide (CO2) and water (H2O). Classify each substance as a reactant of product in the chemical reaction.
Reactants: Ethanol and oxygen Products: Carbon dioxide and water
Which of the following boxes best represents a solution?
Red dots and circles intertwined
Review the concept of electronegativity in the textbook, and rank these elements from the weakest to strongest reducing agent: (a) phosphorus, P; (b) oxygen, O; (c) fluorine, F.
Reducing agents go the opposite from the oxidizing agents. Weakest: Fluorine Middle: Oxygen Strongest: Phosphorus
Fission and Fusion
Releases lots of energy
Fluorine F, phosphorus P, neon N- Rank them from smallest to largest, in terms of size
Smallest=Neon Middle=Fluorine Largest=Phosphorus Because size increases from right to left and from top to bottom
Hydrogen sulfide, H2S, burns in the presence of oxygen, O2, to produce water, H2O, and sulfur dioxide, SO2. Through this reaction, is sulfur oxidized or reduced? 2H2S + 3O2 → 2H2O + 2SO2
Sulfur is oxidized
Which forms the negative ions: the acid or the base?
The acid
An acid and a base react to form a salt, which consists of positive and negative ions. Which forms the positive ions: the acid or the base?
The base
Which of the following contains only a compound?
The blue dot that is attached to the bigger, single red dot.
What happens to the chemical identity of a substance during a physical change?
The chemical identity remains the same.
Distinguish between a solute and a solvent.
The component present in the largest amount is the solvent, and the other components are the solutes.
Soaps form micelles when added to water and can be used to remove dirt or grease from surfaces. The dirt or grease molecules get trapped inside the micelle and can be easily washed away using water. Which of the following statements are correct concerning the use of soap to remove dirt or grease form an object.
The core of a micelle is formed by hydrocarbon chains The dirt particles are generally nonpolar The polar end of soap attracts the water molecules surrounding it Soaps have a polar end and a nonpolar end
How do two structural isomers differ from each other?
The have different configurations
Which of the following diagrams represents the size of the atomic nucleus relative to the size of an atom?
The nucleus is too small for us to see.
What is the relationship between the maximum number of electrons each shell can hold and the number of elements in each period of the periodic table?
The number of elements in a period is equal to the maximum number of electrons in the outermost shell.
Which of the following boxes contains only an element?
The only blue dots
What happens to the properties of elements across any period of the periodic table?
The properties of elements gradually change across any period of the periodic table.
Does the periodic table explain the shell model, or does the shell model explain the periodic table?
The shell model explains the periodic table.
What is the chemical formula for the compound titanium dioxide?
TiO2
For neutral molecules, which statements about covalent electron-dot structures are true?
True- Electrons of covalent compounds may be shared between atoms and for neutral molecules, the number of electrons in the electron-dot structure is the sum of the valence electrons for the atom False- hydrogen atoms are often the central atom of an electron-dot structure and each atom of an electron-dot structure must have eight electrons
List several common transition metals
Tungsten, platinum, and iron
Fission only
Used in nuclear power plants Byproducts have long half-lives
What must be added to a double bond to transform it into an alcohol? Would this be an example of oxidation or reduction?
Water molecule; oxidation
Classify the following compounds as being more likely to dissolve in water or oil.
Water: hydrogen fluoride, potassium bromide, and potassium permanganate Oil: pentane, iodine, and xylene
Observe the reactions given below. Classify the reactants based on whether they are oxidized or reduced. Zn(s)+Cu2+(aq)→Zn2+(aq)+Cu(s) 3Fe(s)+4H2O(g)→Fe2O3(s)+4H2(g)
Zinc and iron get oxidized Water and copper get reduced
What is an alloy?
a mixture of two or more metallic elements
Benzaldehyde is a fragrant oil. If stored in an uncapped bottle, this compound will slowly transform into benzoic acid along the surface. Is this an oxidation or a reduction?
an oxidation
Isotopes are identified by their...
atomic mass number
In molecule, which atom carries the greater POSITIVE CHARGE: C−O?
carbon
Which produces more radioactivity in the atmosphere: coal-fired power plants or nuclear power plants?
coal-fired power plants
Classify the following as a homogenous mixture, heterogenous mixture, element, or compound: table salt
compound
Gamma Ray
deepest penetration Mass-0amu Charge=0
How many atoms are in a sulfur molecule that has the elemental formula S8?
eight
How many atoms are there in one molecule of H3PO4? How many atoms of each element are there in one molecule of H3PO4?
eight in one molecule of H3PO4; three hydrogens, one phosphorus, and four oxygen
Which contributes more to an atom's SIZE?
electrons
An example of a physical change is the...
formation of a cloud
How many electrons are shared in a double covalent bond?
four
An example of a chemical change is the...
growth of a tree
Classify the following as a homogeneous mixture, heterogeneous mixture, element, or compound: planet Earth.
heterogeneous mixture
Classify the following as a homogeneous mixture, heterogeneous mixture, element, or compound: steel.
homogeneous mixture
Classify the following as a homogeneous mixture, heterogeneous mixture, element, or compound: blood.
homogenous mixture
In molecule, which atom carries the greater POSITIVE CHARGE: H−Cl?
hydrogen
As the hydronium ion concentration of a solution increases, does the pH of the solution increase or decrease?
it decreases
What happens to the double bond of a monomer participating in the formation of an addition polymer?
it splits apart releasing two electrons that form two single bonds with new atoms.
Is a biological cell macroscopic, microscopic, or submicroscopic?
microscopic
pH is a measure of the...
negative log of hydronium ion concentration
In molecule, which atom carries the greater POSITIVE CHARGE: Br−Br?
neither
In the following reaction sequence for the catalytic formation of ozone from molecular oxygen, which chemical compound is the catalyst: nitrogen monoxide or nitrogen dioxide? O2+2NO→2NO2 2NO2→2NO+2O 2O+2O2→2O3
nitrogen monoxide
A chemical equation for the combustion of propane, C3H8, is shown. Through this reaction is the carbon oxidized or reduced? C3H8+ 5O2→ 3CO2+ 4H2O
oxidized
What is the IUPAC systematic name for the compound KF?
potassium fluoride
The name of the compound with the formula of K2O is...
potassium oxide
Which contributes more to an atom's MASS: electrons or protons?
protons
The subscripts within a chemical formula indicates the...
ratio of atoms in a compound
What always changes during a chemical reaction?
the arrangement of atomic bonds
Which portion of a soap molecule is nonpolar?
the tail
Which electrons are represented by an electron-dot structure?
valence electrons