Question 1

Alkali metal hydrides are very reactive with water, forming H₂ gas.

Accepted Answer

Alkali metal hydrides (such as lithium hydride, sodium hydride, and potassium hydride) readily react with water to produce hydrogen gas (H2) and the corresponding alkali metal hydroxide (such as lithium hydroxide, sodium hydroxide, and potassium hydroxide). The overall reaction can be written as: MH + H2O → MOH + H2, where M represents the alkali metal. The H₂ gas mentioned in the statement is not a known compound.

Question 2

Hydrogen plays an important role in many industrial processes. Write a balanced chemical equation for its production by the reaction of propane (C₃H₈, obtained from natural gas)and steam.

Accepted Answer

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Question 3

What is carborundum, and how is it prepared.What physical property of carborundum makes it a useful material?

Accepted Answer

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Question 4

Write the formula for the binary hydride you would expect calcium to form.

Accepted Answer

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Question 5

Why is it especially dangerous to mix cyanide salts with acids? Write a chemical equation to illustrate your answer.

Accepted Answer

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Question 6

P₄O₆ and P₄O₁₀ are allotropes of phosphorus.

Accepted Answer

The strings provided do not represent known chemical notations or structures for allotropes of phosphorus. Allotropes of phosphorus are commonly known as white (or yellow), red, and black phosphorus.

Question 7

What element is the most abundant by mass in Earth's crust?

Accepted Answer

Oxygen (O) is the most abundant element by mass in Earth's crust, comprising 46.6% of the crust's mass.

Question 8

Write the chemical formula of the peroxide ion.

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Question 9

Which of these aqueous solutions has the highest pH?

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Question 10

Hydrogen plays an important role in many industrial processes. Write a balanced chemical equation for its production by the water gas reaction.

Accepted Answer

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Question 11

Chlorine gas is prepared commercially by

Accepted Answer

Chlorine gas is commercially prepared by the electrolysis of a solution of sodium chloride (NaCl) in water (H2O). This process is known as the chlor-alkali process. During electrolysis, sodium chloride is split into chlorine gas (Cl2), sodium hydroxide (NaOH), and hydrogen gas (H2).

Question 12

Of the three oxides SiO₂, MgO, and P₄O₁₀, the most acidic oxide is P₄O₁₀.

Accepted Answer

P₄O₁₀ is a peroxo acid, which is a strong acid, and therefore the most acidic of the three oxides. SiO₂ and MgO are not acids.

Question 13

Write a balanced chemical equation to show the production of chlorine by the chlor-alkali process.

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Question 14

The bond energy of F₂ is anomalously low, in comparison with the other halogens, due to the small size of the fluorine atom. Which of the following periodic properties is also anomalously low in the case of fluorine?

Accepted Answer

Fluorine has an anomalously low electron affinity due to the high electron-electron repulsion in its small 2p orbital, making it less favorable to add an extra electron compared to other halogens.

Question 15

Write the chemical formula of the oxide ion.

Accepted Answer

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Question 16

The main commercial source of bromine is

Accepted Answer

The main commercial source of bromine is seawater, which contains approximately 65 parts per million of bromine ions. The bromide ions are extracted from seawater and then treated with chlorine gas to produce elemental bromine.

Question 17

Which one of these species exists as a diatomic element at room temperature?

Accepted Answer

Nitrogen (N) exists as a diatomic element (N2) at room temperature. Na (sodium), B (boron), Ar (argon), and P (phosphorus) do not exist as diatomic elements at room temperature.

Question 18

Write the chemical formula of the superoxide ion.

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Question 19

Write an equation for a laboratory preparation of nitrogen gas.

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Question 20

Which of these aqueous solutions has the lowest pH?

Accepted Answer

NaOH is a strong base, so it will fully dissociate in water to produce hydroxide ions. This results in a high concentration of OH- ions, leading to a low pH. Choices B and C are both salts of weak acids (thiosulfate and borate, respectively) which can only partially hydrolyze in water and result in a slightly basic pH. Choice D is incorrect because NaOH is a strong base and will have a much different pH than the weak acid salts in choices B and C. Choice E is incorrect because the question only provides the molar concentration of the solutions, so Ka values are not necessary to determine the pH.

Quiz 21: Nonmetallic Elements and Their Compounds

Alkali metal hydrides are very reactive with water, forming H2 gas.

Hydrogen plays an important role in many industrial processes. Write a balanced chemical equation for its production by the reaction of propane (C3H8, obtained from natural gas)and steam.