Question 1: Explain what alkanes are and describe their general molecular formula.

Answer: Alkanes are saturated hydrocarbons consisting entirely of single bonds between carbon atoms, with the general molecular formula CnH2n+2.

Question 2: Describe the main difference between saturated and unsaturated hydrocarbons.

Answer: Saturated hydrocarbons, like alkanes, have only single bonds between carbon atoms, while unsaturated hydrocarbons have one or more double or triple bonds.

Question 1: What is the significance of the 'saturation' in saturated hydrocarbons?

Answer: Saturation indicates that all carbon-carbon bonds are single bonds, meaning the molecule has the maximum number of hydrogen atoms possible for its number of carbons.

Question 2: Name one common use of alkanes in everyday life.

Answer: Alkanes are used as fuels, such as in LPG (liquefied petroleum gas).

Question 1: Calculate the number of hydrogen atoms in a molecule of decane (C10H22).

Answer: 22

Question 2: How many carbon atoms are in 50 grams of hexane (C6H14)? (Atomic masses: C = 12 g/mol, H = 1 g/mol)

Answer: Approximately 11.7 carbon atoms

Question 1: Describe a simple experiment to test whether a hydrocarbon sample is an alkane or an alkene.

Answer: One experiment involves adding bromine water to the sample. Alkanes do not react with bromine water without UV light, so the solution remains orange. Alkenes react readily, decolourising the bromine water.

Question 2: Identify three safety precautions to consider when handling alkanes in a laboratory setting.

Answer: Use in a well-ventilated area, avoid open flames due to flammability, and wear safety goggles and gloves.

Question 1: A sample of a hydrocarbon is burned completely, producing 100 kJ of energy. Given that the molar heat of combustion for hexane is approximately -4160 kJ/mol, estimate how many moles of hexane were in the sample.

Answer: Approximately 0.024 mol

Question 2: Based on the energy produced, what can you infer about the purity and composition of the hydrocarbon sample?

Answer: The energy suggests a relatively pure hydrocarbon similar to hexane; impurities or other hydrocarbons would alter the energy output.

Question 1: Explain why alkanes are used as fuels in vehicles and heating systems.

Answer: Alkanes are used as fuels because they are readily combustible, produce a high amount of energy per mole, and are relatively easy to store and transport.

Question 2: Identify a challenge associated with using alkanes as fuels and suggest a possible solution.

Answer: A challenge is pollution from combustion; a solution is developing cleaner-burning fuels or implementing better emission control technologies.