CHEM 101 ACTUAL EXAM QUESTIONS AND CORRECT DETAILED ANSWERS WITH RATIONALES (VERIFIED ANSWERS) ALREADY GRADED A+ NEWEST VERSION
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Course
CHEM 101
Institution
CHEM 101
CHEM 101 ACTUAL EXAM QUESTIONS AND CORRECT DETAILED ANSWERS WITH RATIONALES (VERIFIED ANSWERS) ALREADY GRADED A+ NEWEST VERSION
If a compound's chemical formula was experimentally determined to be 18, the chemical formula could be:
CH4
NH3
H2O
PCl5 - Answer H2O
Use the periodic table to g...
CHEM 101 ACTUAL EXAM QUESTIONS AND
CORRECT DETAILED ANSWERS WITH
RATIONALES (VERIFIED ANSWERS)
ALREADY GRADED A+ NEWEST VERSION
If a compound's chemical formula was experimentally determined to be 18, the chemical
formula could be:
CH4
NH3
H2O
PCl5 - Answer ✔ H2O
Use the periodic table to get the atomic masses of each element. Then you can
calculate the formula mass as such:
H=1.008×2=2.016
O=15.999×1=15.999
Adding these together we get 18.015, which is approximately 18.
The sum of the average atomic masses of all the atoms present in a substance's
formula is known as:
Correct! You nailed it.
the atomic mass
the formula mass (molecular mass)
an atomic mass unit
the mass number - Answer ✔ the formula mass (molecular mass)
The sum of the average atomic masses of all the atoms present in a substance's
formula is known as the formula mass or the molecular mass.
If a compound has a formula mass of 62, the chemical formula could be:
Correct! You nailed it.
Na2O
CaO
KF
MgO - Answer ✔ Na2O
Use the periodic table to get the atomic masses of each element. Then you can
calculate the formula mass as such:
Na=22.990×2=45.980O=15.999×1=15.999
Adding these together we get 61.979, which is approximately 62 amu.
What is the formula mass of a compound with 2 aluminum atoms, 3 sulfur atoms, and 3
oxygen atoms, in atomic mass units?
,Your answer should have six significant figures. - Answer ✔ Correct
answers:$198.159\text{ amu}$198.159 amu
Use the periodic table to get the atomic mass of each element. Multiply the atomic mass
of the element by the number of atoms of that element in the compound.
mass of Al: 26.982×2=53.964
mass of S: 32.066×3=96.198
mass of O: 15.999×3=47.997
Add the mass of each element to find the total.
If a compound's formula mass was experimentally determined to be 58, the chemical
formula could be:
C2H2
C2H4
C2H6
C3H6 - Answer ✔ C2H2
Use the periodic table to get the atomic masses of each element. Then you can
calculate the formula mass as such:
H=1.008×2=2.016
C=12.011×2=24.022
Adding these together we get 26.038, which is approximately 26.
If a compound has a formula mass of 212, the chemical formula could be:
Na2SO4
K2SO4
Na3PO4
K3PO4 - Answer ✔ K3PO4
Use the periodic table to get the atomic masses of each element. Then you can
calculate the formula mass as such:
K=39.098×3=117.294
P=30.974×1=30.974
O=15.999×4=63.996
Adding these together we get 212.264, which is approximately 212 amu.
If a compound has a formula mass of 40, the chemical formula could be:
Yes that's right. Keep it up!
MgF2
NaOH
NaF
KF - Answer ✔ NaOH
Use the periodic table to get the atomic masses of each element. Then you can
calculate the formula mass as such:
H=1.008×1=1.008Na=22.990×1=22.990O=15.999×1=15.999
Adding these together we get 39.997, which is approximately 40 amu.
,A compound with the empirical formula of CH4O and a molar mass of 32 g/mol has a
molecular formula of:
Great work! That's correct.
CH4O
C2H8O2
C2H4O2
C3H8O3 - Answer ✔ CH4O
The empirical formula weight is 32 g/mol so the molar mass divided by that is 3232=1.
This means the molecular formula is the same as the empirical formula.
The molar mass of a compound if 74.14 g/mol and its empirical formula is C4H10O.
What is the molecular formula of this compound?
Perfect. Your hard work is paying off 😀
C8H20O3
CHO
C2H10O3
C4H10O - Answer ✔ C4H10O
The empirical formula weight is 74 g/mol so the molar mass divided by that is
74.14/74=1. That means the molecular formula is the same as the empirical formula, or
C4H10O.
Haley finds that a compound has a molar mass of 64.07 g/mol and an empirical formula
of SO2. What is the molecular formula of this compound?
Great work! That's correct.
SO
SO2
SO4
S2 - Answer ✔ SO2
The empirical formula weight is 64 g/mol so the molar mass divided by this is
64.07/64=1. This means the molecular formula is the same as the empirical formula.
All of the following are reasons why chemistry is known as the "central science",
EXCEPT:
A. Many biological processes involve chemical reactions.
B. Because it intersects with and provides a basis for a variety of other scientific
disciplines.
C. Because it is crucial to understanding other scientific concepts like energy transfer.
D. Because it was created to study all other sciences. - Answer ✔ Because it was
created to study all other sciences.
, Which of the following questions is the best example of a question that could be
answered or explained by studying chemistry?
A. Which part of the country has the most salt-water lakes?
B. What is the identity of this unknown substance?
C. What is the angle of refraction when light enters water?
D. What is the acceleration of a race car in meters/second? - Answer ✔ What is the
identity of this unknown substance?
Why is chemistry helpful in understanding how a toaster creates the brown color and
crispy texture of toast?
A. The properties of the bread molecules are changing in the toaster.
B. The toaster uses electricity.
C. The composition and/or properties of the surface of the toast are somehow changed
by the toaster.
D. The process takes place in the atmosphere. - Answer ✔ C. The composition and/or
properties of the surface of the toast are somehow changed by the toaster.
Which word BEST completes the sentence below:
_________ are any substance made up of matter and can be natural or man-made.
A. atoms
B. chemicals
C. molecules
D. elements - Answer ✔ B. chemicals
Chemistry helps to create:
A. New mathematical equations
B. New ideas about how humans connect
C. New ways to harness renewable energy
D. New theories on spiritual connections - Answer ✔ C. New ways to harness
renewable energy
Chemistry is best defined as the study of which of the following?
A. the properties of living organisms
B. the electrical nature of matter
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