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Straighterline Chemistry Final Exam |Questions with 100% Correct Answers
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Straighterline Chemistry Final Exam|Questions with 100% Correct Answers
Acetylene (properly known as ethyne) and calcium hydroxide are the products of
the reaction between calcium carbide (CaC2) and water. Ethyne can be easily set
on fire. This can be done on the surface of an ice cube, giving it the appearance of
"burning ice". Identify the balanced reaction for the combustion of ethyne and
explain why it burns with intense heat.
A. 2C2H2 + 5O2 à 4CO2 + 2H2O; There is a lot of energy released in this reaction
because there is a triple bond between the carbons in ethyne, which contains a
lot of energy, and this energy is released when the bonds are broken.
B. C2H4 + 3O2 à 2CO2 + 2H2O; There is a lot of energy released in this reaction
because there is a double bond between the carbons in ethyne, which contains a
lot of energy, and this energy is released when the bonds are broken.
C. C2H4 + 3O2 à 2CO2 + 2H2O; There is a lot of energy released in this reaction
because the energy releas - ✔️✔️D. 2C2H2 + 5O2 à 4CO2 + 2H2O; There is a lot of
energy released in this reaction because the energy released when forming the
chemical bonds in four moles of CO2 and two moles of water H2O is much more
than the energy required to break the chemical bonds in two moles of ethyne and
five moles of oxygen.
In some enzymatic reactions, the product of the reaction that is catalyzed by the
enzyme is able to bind to the active site on the enzyme itself. What effect would
this have on the activity of the enzyme? Could this be a biologically useful feature
in some situations? Explain.
,A. This would inhibit the enzyme's activity, slowing it down. No, this could not be
biologically useful and is the sign of a damaged enzyme. Enzymes should catalyze
as many reactions as possible for biological efficiency.
B. This would enhance the enzyme's activity, speeding it up. Yes, this could be
biologically useful because it would maximize production of the product.
C. This would inhibit the enzyme's activity, slowing it down. Yes, this could be
biologically useful because it could prevent over-production of the product.
D. This would enhance the enzyme's activity, slowing it down. No, this would not
be biologically useful because it - ✔️✔️C. This would inhibit the enzyme's activity,
slowing it down. Yes, this could be biologically useful because it could prevent
over-production of the product.
Silicon can be "doped" with other elements by adding small amounts of those
elements to the silicon. This can make "n-type" or "p-type" semiconductors,
depending on what is added to the silicon. What type of semiconductor would be
produced by adding indium to silicon? Why? Which element could you add to
make the opposite type of semiconductor?
A. Doping silicon with indium produces a "p-type" semiconductor. This is because
the indium has more protons than silicon, so it is a "p-type" semiconductor.
Adding arsenic to silicon would produce an "n-type" semiconductor.
B. Doping silicon with indium produces a "n-type" semiconductor. This is because
the indium has more neutrons than silicon, so it is an "n-type" semiconductor.
Adding arsenic to silicon would produce a "p-type" semiconductor.
, C. There is not enough information to answer this question. To know what type of
semiconductor will be produced requires knowledge - ✔️✔️D. Doping silicon with
indium produces a "p-type" semiconductor. This is because the indium has fewer
valence electrons than silicon, and this will produce positively charged "holes" in
the electron structure. Adding arsenic to silicon would produce an "n-type"
semiconductor.
Atoms that have the same number of protons but different numbers of neutrons
are called - ✔️✔️Isotopes
proposed an atomic theory in 1808. - ✔️✔️John Dalton
The magnitude of the electron charge was discovered by - ✔️✔️R. Millikan
E. Rutherford is credited with discovering the - ✔️✔️Nucleus
Metals and non-metals are separated in the periodic table by a(n) - ✔️✔️Staircase
Horizontal rows in the periodic table are called - ✔️✔️Periods
In a chemical reaction, the reactant that is used up first is the ___________. -
✔️✔️Limiting reagent
The concentration of a solution is termed its ________. - ✔️✔️Molarity
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