Organic chem

Question 1

What is the shape and bond angle of a tetrahedral molecule?

Answer 1

Tetrahedral shape with bond angles of 109.5°.

Question 2

What is the shape and bond angle of a trigonal planar molecule?

Answer 2

Trigonal planar shape with bond angles of 120°.

Question 3

What is the shape and bond angle of a linear molecule?

Answer 3

Linear shape with bond angle of 180°.

Question 4

Define structural isomerism.

Answer 4

Compounds with the same molecular formula but different connectivity of atoms.

Question 5

Define stereoisomerism.

Answer 5

Compounds with the same molecular formula and connectivity but different spatial arrangements.

Question 6

What are the main types of stereoisomerism?

Answer 6

Geometric (cis-trans) and optical isomerism.

Question 7

What functional group defines alkanes?

Answer 7

Single C–C and C–H sigma bonds, saturated hydrocarbons.

Question 8

What is the general formula of alkanes?

Answer 8

CnH2n+2.

Question 9

What is the general formula of alkenes?

Answer 9

CnH2n.

Question 10

How do you name organic compounds using IUPAC rules?

Answer 10

Identify longest carbon chain, number it to give substituents lowest numbers, name substituents alphabetically.

Question 11

What is the purpose of curly arrows in reaction mechanisms?

Answer 11

To show the movement of electron pairs during bond breaking/forming.

Question 12

What is free radical substitution?

Answer 12

A reaction where a radical replaces an atom, usually a hydrogen, in an alkane.

Question 13

Describe the initiation step in the chlorination of methane.

Answer 13

UV light breaks Cl₂ into two chlorine radicals (Cl•).

Question 14

Why do alkanes undergo substitution but alkenes undergo addition reactions?

Answer 14

Alkanes are saturated with single bonds; alkenes have double bonds which can open up to add atoms.

Question 15

What is catalytic cracking?

Answer 15

Breaking large hydrocarbons into smaller, more useful ones using heat and catalyst.

Question 16

What conditions are used for catalytic cracking?

Answer 16

Zeolite catalyst, 450°C, slight pressure.

Question 17

What is the difference between catalytic and thermal cracking?

Answer 17

Catalytic uses lower temp and catalyst producing branched and aromatic hydrocarbons; thermal uses high temp and pressure producing more alkenes.

Question 18

What happens to the boiling points of hydrocarbons as chain length increases?

Answer 18

Boiling points increase due to stronger Van der Waals forces.

Question 19

How does branching affect boiling point?

Answer 19

Branching lowers boiling point due to less surface contact and weaker intermolecular forces.

Question 20

Why do alkenes react with bromine water?

Answer 20

Bromine adds across the C=C double bond, decolorizing bromine water.

Question 21

What is Markovnikov’s rule?

Answer 21

In addition reactions, the hydrogen adds to the carbon with more hydrogens already attached.

Question 22

What is the general formula of alcohols?

Answer 22

CnH2n+1OH.

Question 23

What functional group defines alcohols?

Answer 23

Hydroxyl group (–OH).

Question 24

How do you name alcohols?

Answer 24

Replace the ‘–e’ in alkane name with ‘–ol’.

Question 25

What is the reaction of alcohols with sodium?

Answer 25

Alcohol + sodium → alkoxide + hydrogen gas.

Question 26

Write the balanced equation for ethanol reacting with sodium.

Answer 26

2C2H5OH + 2Na → 2C2H5ONa + H2.

Question 27

What is the oxidation product of a primary alcohol under mild conditions?

Answer 27

Aldehyde.

Question 28

What is the oxidation product of a primary alcohol under strong conditions?

Answer 28

Carboxylic acid.

Question 29

What is the oxidation product of a secondary alcohol?

Answer 29

Ketone.

Question 30

Can tertiary alcohols be oxidized easily?

Answer 30

No, they resist oxidation under normal conditions.

Question 31

What reagent is used to oxidize alcohols?

Answer 31

Acidified potassium dichromate (VI), K2Cr2O7 + H2SO4.

Question 32

What color change occurs when a primary or secondary alcohol is oxidized?

Answer 32

Orange dichromate ions reduce to green chromium ions.

Question 33

What is dehydration of alcohols?

Answer 33

Elimination of water to form alkenes using acid catalyst and heat.

Question 34

What conditions are required for alcohol dehydration?

Answer 34

Heat with concentrated sulfuric acid or phosphoric acid catalyst.

Question 35

What is the general formula of haloalkanes?

Answer 35

CnH2n+1X, where X = halogen.

Question 36

How are haloalkanes named?

Answer 36

Prefix the alkane name with the halogen’s name (chloro-, bromo-, iodo-).

Question 37

What makes haloalkanes reactive?

Answer 37

Polar C–X bond with electrophilic carbon.

Question 38

What is nucleophilic substitution?

Answer 38

A nucleophile donates a lone pair to the electrophilic carbon, replacing the halogen.

Question 39

Name three common nucleophiles that react with haloalkanes.

Answer 39

Hydroxide ion (OH⁻), cyanide ion (CN⁻), ammonia (NH3).

Question 40

Write the overall reaction of a haloalkane with hydroxide ion.

Answer 40

Haloalkane + OH⁻ → alcohol + halide ion.

Question 41

What is the difference between primary, secondary, and tertiary haloalkanes?

Answer 41

Number of carbon atoms attached to the carbon bonded to halogen.

Question 42

What is elimination reaction of haloalkanes?

Answer 42

Removal of HX from haloalkane to form alkene under hot ethanolic alkali conditions.

Question 43

What conditions favor elimination over substitution?

Answer 43

Higher temperatures and use of ethanolic rather than aqueous KOH.

Question 44

Describe the mechanism of elimination in haloalkanes.

Answer 44

Base removes proton adjacent to C–X bond, forming a double bond and expelling halide ion.

Question 45

How would you convert an alkene to a dihaloalkane?

Answer 45

React alkene with bromine (Br2) in an addition reaction.

Question 46

How would you convert a haloalkane to an alcohol?

Answer 46

React with aqueous hydroxide ions (nucleophilic substitution).

Question 47

How would you prepare an aldehyde from a primary alcohol?

Answer 47

Gently oxidize primary alcohol with acidified potassium dichromate.

Question 48

How can a carboxylic acid be prepared from an aldehyde?

Answer 48

Further oxidation of aldehyde using acidified potassium dichromate.

Question 49

How would you prepare an alkene from an alcohol?

Answer 49

Dehydration of alcohol by heating with acid catalyst.

Question 50

What does an IR spectrum measure?

Answer 50

Absorption of infrared radiation by molecules causing bond vibrations.

Question 51

What key functional group absorption is seen at around 1700 cm⁻¹ in IR spectra?

Answer 51

C=O (carbonyl) group.

Question 52

How can IR spectroscopy identify alcohols?

Answer 52

Broad O–H stretch around 3200–3600 cm⁻¹.

Question 53

What is mass spectrometry used for in organic chemistry?

Answer 53

Determining molecular mass and fragment pattern to deduce structure.

Question 54

What does the molecular ion peak (M⁺) represent in mass spectra?

Answer 54

The peak corresponding to the intact molecule’s molecular mass.

Question 55

What is Thin Layer Chromatography (TLC) used for?

Answer 55

Separating and identifying components in a mixture.

Question 56

What is the retention factor (Rf) in TLC?

Answer 56

Distance traveled by compound ÷ distance traveled by solvent front.

Question 57

What factors affect the Rf value?

Answer 57

Polarity of compound and solvent.

Question 58

How can you identify compounds using TLC?

Answer 58

Compare Rf values with known standards.