Chem regents study guide
Which sample of HCl(aq) reacts at the fastest rate with a 1.0-gram sample of iron filings?
10. mL of 3 M HCl(aq) at 25°C
Given the equation representing a reaction: 3CuCl2(aq) 2Al(s) → 3Cu(s) 2AlCl3(aq) The oxidation number of copper changes from
2 to 0
Which electron configuration represents an atom of chlorine in an excited state?
2-7-8
2C4H10 13O2 → 8CO2 10H2O energy How many moles of carbon dioxide are produced when 5.0 moles of butane react completely?
20. mol
Which nuclear equation represents a spontaneous decay?
222 218 4 86 Rn ----> 84 Po +2 He
Which equation represents neutralization?
2KOH﴾aq﴿ + H2SO4﴾aq﴿ → K2SO4﴾aq﴿ + 2H2Ol﴾
Which electron shell in an atom of calcium in the ground state has an electron with the greatest amount of energy?
4
What is the amount of heat absorbed when the temperature of 75 grams of water increases from 20.°C to 35°C?
4700 J
A student measures the mass and volume of a sample of aluminum at room temperature, and calculates the density of Al to be 2.85 grams pe
5.6%
What is the percent composition by mass of nitrogen in the compound N2H4 (gram-formula mass 32 g/mol)?
88%
Which statement describes the earliest model of the atom?
An atom is an indivisible hard sphere that consists mostly of empty space and small dense positively charged nucleus
which substance cannot be decomposed by chemical means
C
Which equation represents fermentation?
C6H12O6 → 2CH3CH2OH 2CO
Given the equation representing a reversible reaction: CH3COOH(aq) H2O() ⇌ CH3COO(aq) H3O(aq) According to one acid-base theory, the two H donors in the equation are
CH3COOH and H3O
Which substance is an Arrhenius base?
Ca(OH)2
What is the general formula for the homologous series that includes ethene?
CnH2n
Ethane is a member of the hydrocarbon series with the general formula
CnH2n+2
Which statement describes a concept included in the wave‐mechanical model of the atom?
Electrons, are located in regions called orbitals.
Which trend is observed as the first four elements in Group 17 on the Periodic Table are considered in order of increasing atomic number?
First ionization energy decreases.
which group of elements contains a metalloid
Group 16
Which equation represents energy being absorbed as a bond is broken?
H2 + energy → H + H
Which substance is an electrolyte and a chemical formula for sodium sulfate
H2SO4
Which substance is an Arrhenius acid?
HBr
Which substance is an Arrhenius acid?
HCI
The least polar bond is found in a molecule of
HI
Which formula represents an asymmetrical molecule?
NH3
what formula is an empirical formula?
NH3
Which statement explains why NaBr is classified as a compound?
Na and Br are chemically combined in a fixed proportion.
Based on Table I, which compound dissolves in water by an exothermic process?
NaOH
Which ion in the ground state has the same electron configuration as an atom of neon in the ground state?
O2-
Which statement describes the charge distribution and the polarity of a CH4 molecule?
The charge distribution is symmetrical and the molecule is nonpolar.
Given the equation representing a system at equilibrium: N2O4(g) ⇌ 2NO2(g) Which statement describes the concentration of the two gases in this system?
The concentration of N2O4(g) and the concentration of NO2(g) must be constant.
Compared to the energy of an electron in the second shell of an atom of sulfur, the energy of an electron in
The first shell is lower
which statement describes the relative amounts of energy released during a chemical reaction and a nuclear reaction
The nuclear reaction releases more energy than the chemical reaction.
Which statement describes the components of a mixture?
The proportions of components can vary
Which statement describes the particles of an ideal gas, based on the kinetic molecular theory?
The volume of the particles is considered negligible.
Which statement describes an electrolyte?
When an electrolyte dissolves in water, the resulting solution conducts an electric current.
The three nuclides, U‐233, U‐235, and U‐238, are isotopes of uranium because they have the same number of protons per atom and
a different number of neutrons per atom
The effect of a catalyst on a chemical reaction is to provide a new reaction pathway that results in a different
activation energy
Which type of matter can not be broken down into simpler substances by a chemical change?
an element
The weighted average of the atomic masses of the naturally occurring isotopes of an element is the
atomic mass of the element
As the elements in Period 2 of the Periodic Table are considered in order from left to right, which property generally decreases?
atomic radius
Equilibrium can be reached by
both physical changes and chemical changes
The atoms of which element bond to one another in chains, rings, and networks?
carbon
The only two elements in alkenes and alkynes are
carbon and hydrogen
Hydrocarbons are composed of the elements
carbon and hydrogen, only
During all chemical reactions, charge, mass and energy are
conserved
graphite and diamond are two forms of the same element that differ in the solid phase that differ in their
crystal structures
The ratio of the mass of U-238 to the mass of Pb-206 can be used to
date geological formations
graphite and diamond are both solid forms of the element carbon. which statement explains the different properties of these two forms of carbon?
diamond has a different crystal structure from graphite
Graphite and diamond are two forms of solid carbon at STP. These forms have
different molecular structures and different properties
graphite and diamond are both solid forms at STP, these forms have
different molecular structures and different properties
NaCl﴾aq﴿ + AgNO ﴾aq﴿ → NaNO ﴾aq﴿ + AgCl﴾s﴿ This reaction is classified as a
double replacement reaction
In the late 1800s, experiments using cathode ray tubes led to the discovery of the
electron
which particle has the least mass?
electron
The degree of polarity of a covalent bond between two atoms is determined by calculating the difference in their
electronegativites
Which term is used to describe the attraction that an oxygen atom has for the electrons in a chemical bond?
electronegativity
As the first five elements in Group 14 are considered in order from top to bottom, there are changes in both the
electronegativity values and atomic radius
The bright‐line spectrum of an element in the gaseous phase is produced as
electrons move from higher energy states to lower energy states
Which two terms represent types of chemical formulas?
empirical and structural
which organic compound is a saturated hydrocarbon
ethane
The discovery of the electron as a subatomic particle was a result of
experiments with cathode ray tube
In the ground state, an atom of which element has seven valence electrons?
fluorine (F)
Which electron transition in an excited atom results in a release of energy?
fourth shell to the second shell
During which two processes does a substance release energy?
freezing and condensation
In which type of nuclear reaction do two light nuclei combine to produce a heavier nucleus?
fusion
When an F atom becomes an F ion, the F atom
gains an electron
the difference between the potential energy of the products and the potential energy of the reactants during a chemical change
heat of reaction
Which element tends not to react with other elements?
helium
Which organic prefix is matched with the number of carbon atoms that it represents?
hept‐, 7
The concentration of which ion is increased when LiOH is dissolved in water?
hydroxide ion
Given the equation representing a system at equilibrium: PCl5(g) + energy ⇌ PCl3(g) + Cl2(g) Which change will cause the equilibrium to shift to the right?
increasing the temperature
The mass of an electron is
less than the mass of a neutron
Chemical systems in nature tend to undergo changes toward
lower energy and higher entropy
Which substance can not be broken down by a chemical change?
magnesium
which property can be defined of a substance to be hammered into thin sheets
malleability
which element is a metal that is in the liquid phase at STP
mercury
an element that has a low first ionization energy and good conductivity of heat and electricity is classified as a
metal
A solid sample of copper is an excellent conductor of electric current. Which type of chemical bonds are in the sample?
metallic bonds
Which type of reaction occurs when H ﴾aq﴿ reacts with OH ﴾aq﴿?
neutralization
Which type of reaction occurs when an Arrhenius acid reacts with an Arrhenius base to form a salt and water?
neutralization
Which phrase describes the molecular polarity and distribution of charge in a molecule of carbon dioxide, CO ?
nonpolar and symmetrical
Based on Table S, an atom of which element has the strongest attraction for electrons in a chemical bond?
oxygen
The gold foil experiment led to the conclusion that each atom in the foil was composed mostly of empty space because most alpha particles directed at the foil
passed through the foil
At STP, which property of a molecular substance is determined by the arrangement of its molecules?
physical state
when an atom loses two electrons becomes a
positive ion with a smaller radius
Which subatomic particles each have a mass of approximately 1u?
proton and neutron
What are located in the nucleus
protons and neutrons
Which particles are found in the nucleus of an argon atom?
protons and neutrons
Atoms are neutral because the number of
protons equal the number of electrons
The light emitted from a flame is produced when electrons in an excited state
release energy as they move to lower energy states
Mg﴾s﴿ + 2HCl﴾aq﴿ → MgCl ﴾aq﴿ + H ﴾g﴿ Which type of chemical reaction is represented by the equation?
single replacement
how to find the number of neutrons of an element
the mass number minus the mass = # of neutrons k(42) 19 - atomic number/protons 42 - 19 = 23 neutrons
The atomic mass of an element is the weighted average of the atomic masses of
the naturally occurring isotopes of the element
In all atoms of bismuth, the number of electrons must equal
the number of protons
In the ground state, the valence electrons of a krypton atom are found in
the outermost shell
Which information is sufficient to differentiate a sample of sodium from a sample of silver?
the reactivity of each sample with water
If two atoms are isotopes of the same element, the atoms must have
the same number of protons and a different number of neutrons
Magnesium and calcium have similar chemical properties because their atoms in the ground state have
two electrons in the outermost shell
Table sugar can be separated from a mixture of table sugar and sand at STP by adding
water, stirring, and filtering
