Question 1

What are alkanes in organic chemistry?

Accepted Answer

Alkanes are a class of hydrocarbons in organic chemistry that consist solely of single-bonded carbon and hydrogen atoms. They are saturated compounds, meaning they have the maximum number of hydrogen atoms attached to each carbon. Alkanes follow the general formula CnH2n+2 and are a key topic in the IB MYP Science curriculum.

Question 2

How are alkanes named according to IUPAC nomenclature?

Accepted Answer

In IUPAC nomenclature, alkanes are named based on the number of carbon atoms in their longest continuous chain. The names are derived from a prefix indicating the number of carbons (like 'meth-' for one carbon, 'eth-' for two, 'prop-' for three, etc.) followed by the suffix '-ane'. For example, an alkane with four carbon atoms is called butane.

Question 3

What are the physical properties of alkanes?

Accepted Answer

Alkanes are generally non-polar molecules, which makes them insoluble in water but soluble in organic solvents. They have relatively low boiling and melting points compared to other organic compounds, which increase with molecular weight. Alkanes are also less dense than water, which is why they float.

Question 4

Why are alkanes considered saturated hydrocarbons?

Accepted Answer

Alkanes are considered saturated hydrocarbons because they contain only single bonds between carbon atoms, allowing them to hold the maximum number of hydrogen atoms possible. This saturation makes them relatively stable and less reactive compared to unsaturated hydrocarbons like alkenes and alkynes.

Question 5

What are some common uses of alkanes?

Accepted Answer

Alkanes are widely used as fuels and lubricants. For example, methane, ethane, propane, and butane are used as heating fuels and in cooking. Higher alkanes are found in gasoline, diesel, and jet fuel. Additionally, alkanes serve as starting materials in the synthesis of various chemicals in the petrochemical industry.

Alkanes

Summary and Exam Tips for Alkanes

Exam Tips