Chem mid-term
Mixtures are defined as, 1) always homogeneous 2) combinations of compounds and/ or elements 3) always definite proportions 4) combinations of elements, only
2) combinations of compounds and/or elements
How many kilojoules of heat are needed to raise the temperature of 500 grams of water from 10.0°C to 30.0°C [specific heat of water= 4.18 J/g•k] 1)62.7kJ 2)41.8kJ 3)2.09kJ 4)10.0kJ
2)41.8kJ
If X is the symbol if an element, which pair correctly represents isotopes of X? 1)¹⁵⁸₆₄X and ¹⁵⁸₆₅X 2)¹⁵⁸₆₄X and ¹⁵⁹₆₄X 3)¹⁵⁸₆₄X and ¹⁵⁸₆₄X 4)⁶⁴₁₅₈X and ¹⁵⁸₆₄X
2)¹⁵⁸₆₄X and ¹⁵⁹₆₄X
an atomic mass unit is defined as exactly 1) 1/16 the mass of a ¹⁶O atom 2) 1/12 the mass of a ¹⁶O atom 3) 1/12 the mass of a ¹²C atom 4) 1/16 the mass of a ¹²C atom
3) 1/12 the mass of a ¹²C atom
Which of the following is the electron configuration of fluoride ion (F⁻) in the grond state? 1) 2-9 2) 2-6 3) 2-8 4) 2-7
3) 2-8
Which substance is made of particles with the highest average kinetic energy 1) Br(l) at 20°C 2) H₂0(l) at 30°c 3) Fe(s) at 35°C 4) CO₂(g) at 25°C
3) Fe(s) at 35°C
Usually the term "kernel" includes all parts of the atom accept the 1) orbital electrons 2) protons 3) Valence electrons 4) neutrons
3) Valence electrons
Which of the following is an example of a physical change? 1) acid rain causes the decomposition of a marble stature 2) Hydrochloric acid is neutralized by a base to produce a salt and water 3) concentrated hydrochloric acid is diluted with water 4) Zinc metal is added to hydrochloric acid and a gas is released
3) concentrated hydrochloric acid is diluted with water
As electrical energy is converted into heat energy, the total amount of energy in the system 1) decreases 2) increases 3) remains the same
3) remains the same
An example of a substance that can be decomposed by a chemical charge is 1) iron 2) silver 3) Water 4) Helium
3) water
In 6.20 hours, a 100 gram sample of Ag-112 decays to 25.0 grams. what is the half-life of ag-112?
3.10 hours
34,800
3.48x10⁴ in normal notation
3.56x10³
3560 in scientific notation
3,000,000mm
3km=______mm
how many protons are in the nucleus of an atom if beryllium?
4
What is the possible numer of a sodium atom 1) 12 2) 11 3) 1 4) 23
4) 23
Which phase is endothermic? 1) NH₃(g)→NH₃(l) 2) Fe(l)→Fe(s) 3) H₂0(l)→H₂0(s) 4) CO₂(s)→CO₂(g)
4) CO₂(s)→CO₂(g)
The elements with atomic number 10 has an electron configuration that is the same as 1) Na 2) Cl 3) Cl⁻ 4) Na⁺
4) Na⁺
An ion with 5 protons, 6 neutrons, and a charge of 3+ has an atomic number of
5
What is the total number of valence electrons in an atom if phosphorus in the ground state?
5
.00599
5.94x10⁻³ in normal notation
If two different systems at different temperatures have contact with each other, heat will flow from the system at 1) 50°C to a system at 333K 2) 30°C to a system at 313K 3) 20°C to a system at 303K 4) 40°C to a system at 293K
4) 40°C to a system at 293K
What is the total number of protons in an atom of ³⁶Cl
17
what is the total number of occupied principle energy levels in a neutral atom of neon in the ground state?
2
what is the electron configuration of a calcium ion (Ca²⁺) in the ground state?
2-8-8
2000mL
2.0L=_____mL
What is the atomic number of an atom that forms an ion with 18 electrons and charge of 2⁺?
20
.025L
25mL=____L
2.6cm
26mm=_____cm
Which principle energy level can hold a maximum of 18 electrons?
3
1500mm
150cm_____mm
Which change of phase is exothermic 1) H₂0(l)→H₂0(g) 2) H₂0(l)→H₂0(s) 3) NaCl(s)→NaCl(l) 4) CO₂(s)→CO₂(g)
2) H₂0(l)→H₂0(s)
Which phase change represents deposition? 1) liquid→gas 2) Gas→solid 3)solid→liquid 4)gas→liquid
2) Gas→solid
4
# of sig figs in 0.002030mm
2
# of sig figs in 0.0025cm?
2
# of sig figs in 150pm
5
# of sig figs in 23032kg
1) 63.9cm²
(52.6cm)(1.214cm) what is the product expressed to the correct number of significant figures? 1)63.9cm² 2)64cm² 3)63.86cm² 4)63.8564cm²
Which of the following is the electron configuration of an atom in the round state? 1) 2-8-1 2) 1-8-2 3) 2-7-2 4) 2-7-1-1
1) 2-8-1
at 1 atmosphere, which substance will sublime when heated? 1) CO₂(s) 2) CH₄(g) 3) HC1(aq) 4) H₂C(l)
1) CO₂(s)
Which of the following statements describes a chemical property of the element iodine? 1) It reacts with hydrogen to form a gas 2) It forms a violet-colored gas 3) Its crystals are metallic gray. 4) It dissolves in alcohol
1) It reacts with hydrogen to form a gas
which element has a completely filled third principle energy level? 1) Zn 2) Ar 3) N 4) Fe
1) Zn
Compounds are usually broken down into their component elements by 1) chemical change 2) physical change 3) evaporation 4) filtration
1) chemical change
Which of the following is a part of daltons atomic theory? 1) different atoms combine in simple whole- number ratios to form compounds 2) atoms can be created or destroyed 3) all atoms of a given element are not identical 3) during a chemical reaction, atoms cannot be separated, combined or rearranged
1) different atoms combine in simple whole- number ratios to form compounds
A true solution is best described as a 1) homogeneous mixture 2) homogeneous compound 3) heterogeneous mixture 4) heterogeneous compound
1) homogeneous mixture
which atom contains exactly 15 protons? 1) phosphorus-32 2) nitrogen-15 3)oxygen-15 4) sulfur-32
1) phosphorus-32
Matter is defined as anything that occupies space and has 1)mass 2)odor 3)color 4)a definite shape
1)mass
A radioactive isotope has a half-life of 10 years. What fraction of its original mall will remain unchanged after 50 years?
1/32
1.5x10⁻⁹m
1500pm=_______m
What quantity oh heat does a kilojoule represent? 1) 1/1,000 of a joule 2) 1,000 joules 3) 1/100 of a joule 4) 100 joules
2) 1,000 joules
A 7.0 gram sample of water is heated and the temperature rises from 10°c to 15°c. What is the total amount of heat energy absorbed be the water [specific heat of water= 4.18 J/g•k] 1) 88 joules 2) 146 joules 3) 29 joules 4) 117 joules
2) 146 joules
Which electron configuration represents an atom in the excited state? 1) 2-1 2) 2-2-1 3) 2-8-2 4) 2-8-1
2) 2-2-1
What is the total number of electrons in the second principle energy level of a calcium atom in the ground state
8
2) 4%
A student measures the mass and volume of a piece of aluminum. The measurements are 25.6 grams and 9.1 cubic centimeters. The student calculates the density of the aluminum. What is the percent error of the student's calculated density of aluminum? 1) 1% 2) 4% 3) 2% 4) 3%
4) Ti
At STP, a 7.49-gram sample of an element has a volume of 1.65 cubic centimeters. The sample is most likely, 1) Ta 2) Tc 3) Te 4) Ti
2) potential energy
Energy of position or stored energy is also called? 1) activation energy 2) potential energy 3) Kinetic energy 4) chemical energy
Given the equation: X→⁴₂He+²¹⁶₈₅At What element is represented by X?
Fr
Given: 60 grams of NaOH find: GFM %Na %O moles molecules
GFM: 40 %Na: 57.5% %O: 40% moles: 1.5 molecules: 9.03x10²³
Given: 126 grams of HNO₃ find: GFM %H %N moles molecules
GFM: 63 %H: 2% %N: 22% moles: 2 molecules: 1.204x10²⁴
Given: 4 moles of water find: GFM %H %O grams molecules
GFM= 18 %H= 11% %O= 89% grams= 72 molecules=2.40x10²⁴
3)1.65
In an experiment the gram atomic mass of magnesium was determined to be 24.7. compared to the accepted value 24.3, what is the percent error for this determination? 1)98.4 2)24.7 3)1.65 4)0.400
What celsius temperature is equal to 200 K? [Write the correct formula, show all work]
K= C+273, 200=C+273, (-273), -73°=c
The heat released during fission and fusion reactions comes from the fractional conversion of
Mass to energy
According to the selected radioisotopes chemistry reference table, which is a decay product of Fe-53?
Mn-53
What is the total amount of heat energy needed to change 200 grams of ice to water at 0°C? [write the correct formula, show all work, Express your answer in joules and kilo joules]
Q= M•HOV, Q=200•2260, Q=452,000J AND Q=452kJ
3) 0.029
Using the rules of sig figs, the sum of 0.027 gram and 0.0023 gram should be expresse as 1) 0.0293 gram 2) 0.03 gram 3) 0.029 gram 4) 0.030 gram
2) 7.44g
What is the sum of 0.421gram+5.263grams+2.13grams to the correct number of significant figures 1)7g 2)7.44g 3)7.4g 4)7.435g
Which particle is given off when phosphorus-32 undergoes a transmutation reaction?
a beta particle
The questions below refer to an atom that has 17 protons, 19 neutrons and 17 electrons a)what is the atomic number of this atom? b) what is the mass number of this atom? c) write the electron configuration for this atom? d) identify this atom
a) 17 b) 35 c) 2-8-7 d) Cl
The list below shoes four samples: A,B,C and D A)HC1(aq) B)NaCl(aq) C)HC1(g) D)NaCl(s) which samples are substances? 1)C and D 2) C and B 3) A and C 4) A and B
a) C and D
In the modern atomic theory, atoms are composed of three major subatomic particles a) name two types of subatomic particles contained in the nucleus of the atom and state the charge associated with each? b) name the subatomic particle found in the region outside the nucleus. What charge is associated with this type of particle?
a) proton, positive and neutron, neutral b) electron, negative
What particle has a negative charge and a mass that is approximately 1/1,836 the mass of a proton?
an electron
Isotopes of the same element must also have the same
atomic number
What element is used for dating archaeological discoveries?
carbon-14
in the nuclear reactor, the radioisotope U-235 serves as a
fissionable material
The characteristic of spectral lines of elements are caused when electrons in an excited atom move from
higher to lower energy levels
Which radioisotope is used to diagnose thyroid disorders?
iodine-131
The atomic mass of an element is defined as the weighted average mass of that element's,
naturally occurring isotopes
A particle of matter contains 6 protons, 7 neutrons, and 6 electrons. This particle must be a
neutral carbon atom
What particle has approximately the same mass as a proton?
neutron
what particle is electrically neutral?
neutron
The stability of an isotope is based on the ratio of
neutrons and protons
The mass number of an atom is equal to the number of
neutrons plus protons
The atoms in a sample of an element must contain nuclei with the same number of
protons
What are the nucleons in an atom
protons and neutrons
The atomic number of an atom is always equal to the total number of
protons in the nucleus
Atoms of ¹⁶O, ¹⁷O and ¹⁸O have the same number of
protons, but a different number of neutrons
As the number of neutrons in the nucleus of an atom increases, the nuclear charge of the atom
remains the same
When the electrons of an excited atom fall back to lower levels, there is an emission of energy that produces
spectral lines
Brain tumors can be located by using an isotope of
technetium-99
The chemical properties of an atom are related to the number of its
valence electrons
the amount of matter an object possesses
what is mass?
the amount of space an object takes up
what is volume?
4) 0k
which temperature represents absolute zero? 1)273°c 2)273°k 3)0°c 4)0 k
