Question 1
A)
Use the periodic table and example bond table to answer the question.
Example Bond Energies of Ionic Compounds
Li–F = 1036 kJ/mol
Li-Br = 807 kJ/mol
Na-F= 923 kJ/mol
Na-Br = 747 kJ/mol
Given the general trend with bond energies, which of the compounds would have the smallest bond energy?
(1 point)
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Cs-Br
Cs-Br
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K-Br
K-Br
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Cs-F
Cs-F
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K--F
Question 2
A)
Potassium carbonate (K2CO3) has one potassium atom bonded to carbon, and that carbon is also bonded to three oxygens. Their electronegativities are shown in the list:
• K: 0.82
• C: 2.55
• O: 3.44
How would you describe the bonds (K–C and C–O) in this molecule?
(1 point)
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K–C is polar covalent, and C–O is polar covalent.
K–C is polar covalent, and C–O is polar covalent.
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K–C is ionic, and C–O is polar covalent.
K–C is ionic, and C–O is polar covalent.
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K–C is polar covalent, and C–O is nonpolar covalent.
K–C is polar covalent, and C–O is nonpolar covalent.
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K–C is ionic, and C–O is nonpolar covalent.
K–C is ionic, and C–O is nonpolar covalent.
Question 3
A) What is true about kinetic energy?(1 point)
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Molecules within a substance have kinetic energy when that substance moves.
Molecules within a substance have kinetic energy when that substance moves.
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Cold molecules have potential energy but no kinetic energy, as kinetic energy is experienced as heat.
Cold molecules have potential energy but no kinetic energy, as kinetic energy is experienced as heat.
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All molecules are in constant motion, so they all have some kinetic energy.
All molecules are in constant motion, so they all have some kinetic energy.
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Molecules of liquids and gases are in constant motion, so they have kinetic energy.
Molecules of liquids and gases are in constant motion, so they have kinetic energy.
Question 4
A) Substance A reacts spontaneously with substance B at room temperature. Substance A reacts with substance C at room temperature only in the presence of a catalyst. Which statement best explains this difference?(1 point)
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The reaction between substances A and B has a lower activation energy than the reaction between substances B and C.
The reaction between substances A and B has a lower activation energy than the reaction between substances B and C.
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The reaction between substances A and B is endothermic.
The reaction between substances A and B is endothermic.
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The reaction between substances A and B is exothermic.
The reaction between substances A and B is exothermic.
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The reaction between substances A and B has a lower relative potential energy than the reaction between substances B and C.
The reaction between substances A and B has a lower relative potential energy than the reaction between substances B and C.
Question 5
A) Hydrochloric acid and sodium hydroxide react to produce water and sodium chloride in an endothermic reaction. Which statement must be true of the reaction?(1 point)
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More bond energy is absorbed on the reactants side than is released on the products side.
More bond energy is absorbed on the reactants side than is released on the products side.
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The bond energy used to break the bonds in hydrochloric acid and sodium hydroxide is less than the energy released to form the bonds in water and sodium chloride.
The bond energy used to break the bonds in hydrochloric acid and sodium hydroxide is less than the energy released to form the bonds in water and sodium chloride.
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The energy of each bond in water and sodium chloride is greater than the energy of each bond in hydrochloric acid and sodium hydroxide.
The energy of each bond in water and sodium chloride is greater than the energy of each bond in hydrochloric acid and sodium hydroxide.
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The total bond energy of water and sodium chloride is greater than the total bond energy of hydrochloric acid and sodium hydroxide.
The total bond energy of water and sodium chloride is greater than the total bond energy of hydrochloric acid and sodium hydroxide.
Question 6
A)
Imagine a graph. The x-axis is labeled "Time" and is measured in seconds, and the y-axis is labeled "Potential Energy" and is measured in kilojoules. The slope starts at 0 seconds with a plateau at 25 kJ. This plateau is labeled "Reactants." The slope then rises to a peak labeled "Activation Energy" at 78 kJ. Finally the slope drops to a plateau at 14 kJ and is labeled "Products."
What does the graph described above represent?
(1 point)
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rate of Reaction graph
rate of Reaction graph
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an endothermic reaction
an endothermic reaction
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a phase change graph
a phase change graph
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an exothermic reaction
an exothermic reaction
Question 7
A) Endothermic reactions absorb a lot of energy. Exothermic reactions give off a lot of energy. Which type of reaction has a higher activation energy? Which one takes more energy to break up the bonds of the reactants?(1 point)
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Endothermic reactions have a higher activation energy. Endothermic reactions require more energy to break up the bonds of the reactants.
Endothermic reactions have a higher activation energy. Endothermic reactions require more energy to break up the bonds of the reactants.
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Exothermic reactions have a higher activation energy. Exothermic reactions require more energy to break up the bonds of the reactants.
Exothermic reactions have a higher activation energy. Exothermic reactions require more energy to break up the bonds of the reactants.
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Exothermic reactions have a higher activation energy. Endothermic reactions require more energy to break up the bonds of the reactants.
Exothermic reactions have a higher activation energy. Endothermic reactions require more energy to break up the bonds of the reactants.
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Endothermic reactions have a higher activation energy. Exothermic reactions require more energy to break up the bonds of the reactants.
Endothermic reactions have a higher activation energy. Exothermic reactions require more energy to break up the bonds of the reactants.
Question 8
A) Why is thermal energy (heat) required to freeze ice into crystals?(1 point)
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Heat must be absorbed by the products in order to convert from the reactants.
Heat must be absorbed by the products in order to convert from the reactants.
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Heat must be absorbed by the reactants and the products.
Heat must be absorbed by the reactants and the products.
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Heat must be released by the reactants and the products.
Heat must be released by the reactants and the products.
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Heat must be released by the products in order to convert from the reactants.
Heat must be released by the products in order to convert from the reactants.
Question 9
A)
Cobalt ions form complex ions with water and chloride as shown in the reaction. The left side of the reaction is pink, and the right side of the reaction is blue.
Co(H2O)62+ + 4Cl– + heat ⇄ CoCl42–+ 6H2O
Which statement about the system at equilibrium is correct?
(1 point)
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Adding water to a purple solution will turn it blue.
Adding water to a purple solution will turn it blue.
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Cooling a purple solution will turn it pink.
Cooling a purple solution will turn it pink.
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Heating a blue solution will turn it purple.
Heating a blue solution will turn it purple.
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Adding hydrogen chloride (HCl) to a blue solution will turn it purple.
Adding hydrogen chloride (HCl) to a blue solution will turn it purple.
Question 10
A) Why are rubber and metal both useful while making wire?(1 point)
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Both are good insulators, but one is flexible while the other is rigid.
Both are good insulators, but one is flexible while the other is rigid.
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Both are flexible, but one reflects electromagnetic waves well while the other transmits them.
Both are flexible, but one reflects electromagnetic waves well while the other transmits them.
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Both are flexible, but one conducts electricity while the other insulates.
Both are flexible, but one conducts electricity while the other insulates.
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Both are good insulators, but one is more ductile than the other.
Both are good insulators, but one is more ductile than the other.
1. Cs-Br
2. Fr–Cl = 2.46
3.Hotter molecules have more kinetic energy.
4.The reaction is exothermic.
5. More bond energy is absorbed on the reactants side than is released on the products side.
6. an exothermic reaction
7. Endothermic reactions have a higher activation energy. Endothermic reactions require more energy to break up the bonds of the reactants.
8. Heat must be released by the products in order to convert from the reactants.
9. Cooling a purple solution will turn it pink.
10. Both are flexible, but one conducts electricity while the other insulates.
11. high pressure, high temperature water extraction
12. reducing environmental impact
13. 15
14. The number of atoms, type of elements, and mass of reactants and products are equal.
15. 64 grams
16. 1.503×1023
17. The relative numbers of protons and neutrons can differ before and after the change, but the total number of those particles remains the same.
18. Fission is a process in which a large nucleus is split into smaller nuclei.
19. beta-minus decay
20. alpha decay
21. Greenhouse gases have more than two atoms, allowing them to vibrate and release radiation, warming the atmosphere.
22. cause: acid rain
consequence: destruction of crops
23. toxic bacteria in the water supply
24. It reaches hard to get to oil and gas deposits.
I think questions 2, 3, and 18 have different answers but i’m sure you can find them online somewheres. but all the rest of the answers are accurate
^These answers are for the chemistry B semester exam which has 24 questions. :))
These are also some other questions that may be switched up or different. just Double check questions for this exam and answers to be safe!!
4. Substance A reacts spontaneously with substance B at room temperature. Substance A reacts with substance C at room temperature only in the presence of a catalyst. Which statement best explains this difference?
> The reaction between substances A and B has a lower activation energy than the reaction between substances B and C.
12. To make high-quality tools that last, it is necessary to combine steel with other elements. Which combination is the best choice for the creation of a hammer?
> steel + vanadium for shock absorption
18. A large room is filled with mousetraps, each trap set with two plastic balls on the arm of the trap. A single plastic ball is thrown into the room, setting off one trap. This causes three plastic balls to be in the air, which then land and set off three other traps, and so on. How could this be evaluated as a model for fission?
> The plastic balls are a good representation of neutrons, but there is no splitting of nuclei as happens in fission.