HAT Organic Chemistry Test one

What is the general formula for alkanes?

• CnH2n+1OH

• CnH2n

• CnH2n-2

• CnH2n+2

• CnH2nO2

Answer explanation

The general formula for alkanes is CnH2n+2, where 'n' is the number of carbon atoms. This formula accounts for the maximum number of hydrogen atoms that can bond with carbon in a saturated hydrocarbon.

(Ch. 22) What type of bonds do alkanes contain?

• Metallic bonds

• Single covalent bonds

• Double bonds

• Ionic bonds

• Triple bonds

Answer explanation

Alkanes contain single covalent bonds, which are formed by the sharing of one pair of electrons between two atoms. This type of bond is characteristic of alkanes, making them saturated hydrocarbons.

(Ch. 22) What is the main source of alkanes?

• Natural gas

• Wood

• Charcoal

• Coal

• Crude oil

Answer explanation

The main source of alkanes is crude oil, which is a complex mixture of hydrocarbons. While natural gas also contains alkanes, crude oil is the primary source for their extraction and production.

(Ch. 22) To which homologous series does methane belong?

• A. Alkanes

• B. Alcohols

• C. Esters

Answer explanation

Methane (CH4) is a saturated hydrocarbon, which classifies it as an alkane. Alkanes are characterized by single bonds between carbon atoms, making option A the correct choice.

What is the chemical formula for methane?

• C4H10

• C3H8

• CH4

• C2H6

• CH3OH

Answer explanation

The formula for methane is CH4, which consists of one carbon atom and four hydrogen atoms. The other options represent different hydrocarbons or alcohols, making CH4 the correct choice.

What happens to alkanes during complete combustion?

• Produce CO and H2

• Produce SO2 and H2O

• Produce CO2 and H2O

• Produce CH4 and O2

• Produce CO2 and SO2

Answer explanation

In complete combustion, alkanes react with oxygen to produce carbon dioxide (CO2) and water (H2O). This is the most efficient combustion process, resulting in the correct answer: Produce CO2 and H2O.

Which alkane has the formula C₄H₁₀?

• Propane

• Butane

• Pentane

• Methane

• Ethane

Answer explanation

The alkane with the formula C4H10 is butane. Alkanes follow the formula CnH2n+2, and for n=4, this gives C4H10, which corresponds to butane. Propane (C3H8), pentane (C5H12), methane (C1H4), and ethane (C2H6) do not match.

Which property increases as the number of carbon atoms in alkanes increases?

• Odour strength

• Flammability

• Solubility in water

• Reactivity with bromine water

• Boiling point

Answer explanation

As the number of carbon atoms in alkanes increases, the boiling point also increases due to greater van der Waals forces between larger molecules. This is why boiling point is the correct choice.

Which catalyst is used in the cracking of alkanes?

• Iron

• Silica or alumina

• Nickel

• Platinum

• Copper

Answer explanation

Silica or alumina are commonly used catalysts in the cracking of alkanes due to their ability to facilitate the breaking of carbon-carbon bonds, making them effective in producing smaller hydrocarbons.

(Ch. 22) What is cracking used for?

• Purifying crude oil

• Measuring hydrocarbon content

• Joining small hydrocarbons into larger ones

• Breaking large hydrocarbons into smaller ones

• Removing sulphur

Answer explanation

Cracking is a process used in the petroleum industry to break large hydrocarbons into smaller, more useful molecules, such as gasoline and diesel. This makes 'Breaking large hydrocarbons into smaller ones' the correct choice.