Week 6 Flashcards

1
Q

Alkanes are the ________ and _______reactive hydrocarbon species containing c and h atoms

A

simplest
least

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2
Q

Its structural feature singly bonded C-C and C-H or a _______

A

lack of unsaturation

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3
Q

______ alkanes and ______ alkanes have different physical and chemical properties

A

straight-chain
branched

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4
Q

Alkanes can exist as ___, ____, ____ at room temperature

A

gas, liquid, solids

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5
Q

Alkanes contain only C-C and C-H sigma bonds which are ______ ______ due to very small difference of electronegativity between carbon and hydrogen

A

almost nonpolar

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6
Q

(True or False)
Alkanes possess strong Van der Waals’ forces as the intermolecular forces

A

False
(weak van der waals forces)

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7
Q

(True or False)
Alkanes possess weak dipole-dipole forces as the intermolecular forces

A

False
(van der waals forces)

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8
Q

First four carbon members exist as

A

gases

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9
Q

C5 to C17 exist as

A

liquids

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10
Q

C18 and up exist as

A

waxy solids

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11
Q

(True or False)
Solid alkanes are normally hard with high melting point

A

False
(soft; low)

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12
Q

(True or False)
Solid alkanes are normally soft with low melting point due to strong repulsive forces generated between electrons on neighboring atoms

A

True

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13
Q

The strong repulsive forces ______ the weak van der waals forces of attraction

A

counterbalance

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14
Q

(True or False)
Intermolecular forces (IMFs) exist between atoms in a molecule

A

False
(exist between molecules)

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15
Q

Types of Intermolecular Forces (IMFs)

A

(1) Van der Waals Forces
(2) Dipole-dipole
(3) Hydrogen Bonding

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16
Q

(True or False)
Van der Waals Forces is the strongest

A

False
(weakest)

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17
Q

(True or False)
Hydrogen Bonding is the strongest

A

True

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18
Q

Intramolecular forces exist between ________

A

atoms in a molecule

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19
Q

Types of Intramolecular forces

A

(1) Electrostatic/Ionic bond
(2) Covalent bond
(3) Metallic bond

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20
Q

(True or False)
As the elevation increases, pressure increases

A

False
(decreases)

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21
Q

(True or False)
As the carbon increases, boiling point increases, molecular weight increases

A

True

22
Q

Alkanes with even carbon atoms have ______ melting points than those with an odd number of carbon atoms

A

higher

23
Q

(True or False)
As the branching increases, boiling point decreases

A

True

24
Q

(True or False)
Branching increases, surface area increases, van der waals forces increases

A

False
(surface area reduces, van der waals forces reduces)

25
Q

(True or False)
Volatility decreases with decrease in chain length

A

False
(increase in chain length)

26
Q

(True or False)
The more the branching, the lower is the volatility

A

False
(the greater the volatility)

27
Q

(True or False)
The lower the volatility, the lower the boiling point

A

True

28
Q

(True or False)
The densities of alkanes increase with increase molecular masses but become constant at about 0.10 g/cm^3

A

False
(0.8 g/cm^3)

29
Q

(True or False)
All alkanes are lighter than water

A

True

29
Q

(True or False)
Densities does not varies with temperature

A

False
(varies)

30
Q

(True or False)
Alkanes are soluble in both water and organic solvents

A

False
(not soluble in water)

31
Q

In water, the primary intermolecular attractions are

A

hydrogen bonds

32
Q

are chemical species which, in the course of chemical reactions, acquire electrons, or a share in electrons, from other molecules or ions.

A

Electrophilic reagents

33
Q

is a chemical reaction with oxygen in which alkane is converted into carbon dioxide and water with the release of heat energy

A

combustion (oxidation)

34
Q

The heat released on complete combustion of one mole of a substance is called _______ and the reaction is called _______

A

heat combustion; exothermic

35
Q

(True or False)
In exothermic, they give off heat

A

True

36
Q

(True or False)
Alkanes can not be used as a source of energy

A

False
(can be used)

37
Q

(True or False)
Product and coefficients change

A

False
(only the coefficients)

38
Q

Is a substitution reaction wherein one or more hydrogen atoms is/ are replaced by halogen atom/s

A

Halogenation

39
Q

(True or False)
Chlorinations and brominations are normally endothermic

A

False
(exothermic)

40
Q

This reaction is done by heating the HC with the vapors of nitric acid at 420° C

A

Nitration

41
Q

(True or False)
Nitration is done by heating the HC with the vapors of nitric acid at 189 ° C

A

False
(420° C)

42
Q

The complex alkanes with high molecular weights that are found in crude oil are frequently broken into smaller, more useful alkanes by _________

A

Thermal cracking

43
Q

Thermal cracking is typically performed at _______ and often in the presence of a _______

A

high temperature; catalyst

44
Q

Alkenes and alkanes can be separated by

A

Fractional distillation

45
Q

The cleavage of C-C and C-H bonds under the influence of heat is called

A

Pyrolysis

46
Q

Pyrolysis in petroleum industry is known as

A

Cracking

47
Q

This process is important in modifying the carbon chain length of higher hydrocarbons obtained by the distillation of crude oil

A

Cracking

48
Q

The conversion of long chain aliphatic hydrocarbons into aromatic hydrocarbons with the same number of carbon atoms is called

A

Reforming

49
Q

Catalytic hydrogenation is also called

A

Sabatier- Sendern’s reactions or S-S reactions

50
Q

It is used for symmetrical alkanes

A

Wurtz reaction

51
Q

Reaction where Na-salt of carboxylic acid is heated with soda lime (NaOH & CaO), alkane is obtained having one carbon less than salt by removal of a molecule of CO2

A

Decarboxylation