Chapter 12, Problem 29P

Interpretation Introduction

(a)

Interpretation:

If the given statement is true or false should be determined.

Concept Introduction:

Alkenes or olefins are the unsaturated hydrocarbons. They are organic compounds with one or more carbon-carbon double bonds. Alkenes are more reactive than alkanes. They undergo many characteristic reactions namely Addition reactions, oxidation reactions and combustion reactions.

Answer to Problem 29P

The statement istrue.

Explanation of Solution

Alkenes are unsaturated hydrocarbons with carbon-carbon double bonds. The combustion reaction takes place in the presence of air. The combustion of alkenes produces carbon dioxide and water.

Hence, the given statement is true.

Interpretation Introduction

(b)

Interpretation:

The given statement is true or false should be determined.

Concept Introduction:

Alkenes or olefins are the unsaturated hydrocarbons. They are organic compounds with one or more carbon-carbon double bonds. Alkenes are more reactive than alkanes. They undergo many characteristic reactions namely Addition reactions, oxidation reactions and combustion reactions.

Answer to Problem 29P

The statement is true.

Explanation of Solution

The addition reaction of alkenes is one double bond of alkene and one single bond of a second reactant break, and three new single bonds are formed such that the addition of the second reactant occurs at the carbon atoms of the double bond. Hence, the two new single bonds are formed at the doubly bonded carbon atoms. Therefore, the given statement is true.

Interpretation Introduction

(c)

Interpretation:

The given statement is true or false should be determined.

Concept Introduction:

Alkenes or olefins are the unsaturated hydrocarbons. They are organic compounds with one or more carbon-carbon double bonds. Alkenes are more reactive than alkanes. They undergo many characteristic reactions namely Addition reactions, oxidation reactions and combustion reactions.

Answer to Problem 29P

The statement is true.

Explanation of Solution

Regioselectivity means the preference of making or breaking of bonds over all other possibilities. Markovnikov's rule states that in the addition of a halogen acid to an alkene, hydrogen goes to the carbon atom in a double bond that bears a higher number of hydrogen atoms. Thus, it indicates the position of the attack. Hence, Markovnikov's rule refers to the regioselectivity of the carbon-carbon double bond. Therefore, the given statement is true.

Interpretation Introduction

(d)

Interpretation:

The given statement is true or false should be determined.

Concept Introduction:

Alkenes or olefins are the unsaturated hydrocarbons. They are organic compounds with one or more carbon-carbon double bonds. Alkenes are more reactive than alkanes. They undergo many characteristic reactions namely Addition reactions, oxidation reactions and combustion reactions.

Answer to Problem 29P

The statement is true.

Explanation of Solution

Markovnikov's rule states that addition of a halogen acid (HX, x = Cl, Br or I) to an alkene, hydrogen goes to the carbon atom in the double bond that bears a higher number of hydrogen atoms. In additionof HCI, HBr, and HI to an alkene, hydrogen attaches to the carbon of the double bond that already has a greater number of hydrogen atoms bonded to it. Therefore, the given statement is true.

Interpretation Introduction

(e)

Interpretation:

The given statement is true or false should be determined.

Concept Introduction:

Alkenes or olefins are the unsaturated hydrocarbons. They are organic compounds with one or more carbon-carbon double bonds. Alkenes are more reactive than alkanes. They undergo many characteristic reactions namely Addition reactions, oxidation reactions and combustion reactions.

Answer to Problem 29P

The statement is false.

Explanation of Solution

A carbocation is a carbon atom with three bonds and is deficient in one pair of the electrons, thus, acquiring a positive charge. Therefore, the given statement is false.

Interpretation Introduction

(f)

Interpretation:

The given statement is true or false should be determined.

Concept Introduction:

Alkenes or olefins are the unsaturated hydrocarbons. They are organic compounds with one or more carbon-carbon double bonds. Alkenes are more reactive than alkanes. They undergo many characteristic reactions namely Addition reactions, oxidation reactions and combustion reactions.

Answer to Problem 29P

The statement is true.

Explanation of Solution

The carbocation is derived from ethylene by the attack of a proton as depicted in the equation is CH₃ CH₂ +.

Therefore, the given statement is true.

Interpretation Introduction

(g)

Interpretation:

The given statement is true or false should be determined.

Concept Introduction:

Alkenes or olefins are the unsaturated hydrocarbons. They are organic compounds with one or more carbon-carbon double bonds. Alkenes are more reactive than alkanes. They undergo many characteristic reactions namely Addition reactions, oxidation reactions and combustion reactions.

Answer to Problem 29P

The statement is true.

Explanation of Solution

The mechanism of the addition of HX to an alkene is a two-step reaction.

Step 1: The formation of the carbocation. In the first step of the reaction, the proton is added to the double bond, and the carbocation is generated as carbocation intermediate.

Step 2: The Nucleophilic attack. Then, a halide ion which is a nucleophile attacks the carbocation, forming an additional product.

Therefore, the given statement is true.

Interpretation Introduction

(h)

Interpretation:

The given statement is true or false should be determined.

Concept Introduction:

Alkenes or olefins are the unsaturated hydrocarbons. They are organic compounds with one or more carbon-carbon double bonds. Alkenes are more reactive than alkanes. They undergo many characteristic reactions namely Addition reactions, oxidation reactions and combustion reactions.

Answer to Problem 29P

The statement is true.

Explanation of Solution

The addition of water is known as hydration. According to Markovnikov's rule, in acid, the catalyzed addition of water to an alkene water molecule is added to the carbon-carbon double bond. Furthermore, in the presence of acid, the alkene is converted to alcohol. Therefore, the given statement is true.

Interpretation Introduction

(i)

Interpretation:

The given statement is true or false should be determined.

Concept Introduction:

Alkenes or olefins are the unsaturated hydrocarbons. They are organic compounds with one or more carbon-carbon double bonds. Alkenes are more reactive than alkanes. They undergo many characteristic reactions namely Addition reactions, oxidation reactions and combustion reactions.

Answer to Problem 29P

The statement is true.

Explanation of Solution

The addition of Br₂ to a carbon-carbon double bond takes place at room temperature. Thus, if a compound fails to react with Br₂, then the compound does not contain a double bond. Therefore, the given statement is true.

Interpretation Introduction

(j)

Interpretation:

The given statement is true or false should be determined.

Concept Introduction:

Alkenes or olefins are the unsaturated hydrocarbons. They are organic compounds with one or more carbon-carbon double bonds. Alkenes are more reactive than alkanes. They undergo many characteristic reactions namely Addition reactions, oxidation reactions and combustion reactions.

Answer to Problem 29P

The statement is true.

Explanation of Solution

The addition of H₂ is known as reduction. During a reaction with molecular H₂, all of the alkenes, are converted to alkanes. Hence, hydrogen is added to the double bond of an alkene. Thus, the given statement is true.

Interpretation Introduction

(k)

Interpretation:

The given statement is true or false should be determined.

Concept Introduction:

Alkenes or olefins are the unsaturated hydrocarbons. They are organic compounds with one or more carbon-carbon double bonds. Alkenes are more reactive than alkanes. They undergo many characteristic reactions namely Addition reactions, oxidation reactions and combustion reactions.

Answer to Problem 29P

The statement is false.

Explanation of Solution

Catalytic reduction is the process in which a substance is reduced by hydrogen in the presence of a catalyst. The catalytic reduction of cyclohexene is the addition of H₂ across the double bond that is present in the cyclic ring. The resultant product is cyclohexane, not hexane. Thus, the given statement is false.

Interpretation Introduction

(l)

Interpretation:

The given statement is true or false should be determined.

Concept Introduction:

Alkenes or olefins are the unsaturated hydrocarbons. They are organic compounds with one or more carbon-carbon double bonds. Alkenes are more reactive than alkanes. They undergo many characteristic reactions namely Addition reactions, oxidation reactions and combustion reactions.

Answer to Problem 29P

The statement is false.

Explanation of Solution

The acid catalyzed hydration of alkene is completed in three steps. The first step includes the addition of a proton (from acid) to the double bond that results in the formation of a carbocation, and hydrogen attaches to one of the doubly bonded carbons. In the second step, an oxygen atom of a water molecule attacks the positively charged carbon, and the water molecule attaches to it, forming an intermediate called an oxonium ion. In the third step, the proton is regenerated again by losing H+ from the oxonium ion, Therefore, in the final product, OH comes from a water molecule, while H comes from the acid used as a catalyst. Thus, the given statement is false.

Interpretation Introduction

(m)

Interpretation:

The given statement is true or false should be determined.

Concept Introduction:

Alkenes or olefins are the unsaturated hydrocarbons. They are organic compounds with one or more carbon-carbon double bonds. Alkenes are more reactive than alkanes. They undergo many characteristic reactions namely Addition reactions, oxidation reactions and combustion reactions.

Answer to Problem 29P

The statement is false.

Explanation of Solution

Oxidation is characterized as a gain in oxygen or a loss of hydrogen or a molecule. The alkene on the acid-catalyzed hydration is converted into alcohol. Thus, the conversion of CH2 = CH2 to ethanol is an addition reaction in which a molecule of water is added to the double bond. Thus, there is neither a loss of hydrogen nor a gain of oxygen. Hence, this is an addition reaction and not an oxidation reaction, so, the given statement is false.

Interpretation Introduction

(n)

Interpretation:

The given statement is true or false should be determined.

Concept Introduction:

Alkenes or olefins are the unsaturated hydrocarbons. They are organic compounds with one or more carbon-carbon double bonds. Alkenes are more reactive than alkanes. They undergo many characteristic reactions namely Addition reactions, oxidation reactions and combustion reactions.

Answer to Problem 29P

The statement is false.

Explanation of Solution

According to Markovnikov's rule, in the acid-catalyzed hydration of alkene, water is added to the double bond of alkene such that the addition of the H and OH groups occur. Furthermore, it says that H is added to the carbon with more of the hydrogen atoms. The acid catalyzed hydration of 1-butene and 2-butene both result in the formation of 2-butanol. Hence the given statement is false.