Question

Identify each of the highlighted materials as an element, a compound, or a mixture, and explain your reasoning.

Answer 1

Answer 1) Butane : It is a compound which is made up by combination of elements of carbon and hydrogen together. It contains four carbon atoms which has ten atoms of hydrogen. The bonds between carbon and hydrogen are formed by covalently sharing of electrons. Therefore, butane is a compound.

Answer 2) Benzene : It is also a compound. Benzene contains six molecules of carbon and six molecules of hydrogen. They are covalently bonded with hydrogen atoms around the carbon atoms. It is termed as compound because it cannot be separated chemically.

Answer 3) Gasoline : This is an example of mixture. Gasoline usually contains mixture of many hydrocarbons in the compound state. It consists of mainly hydrocarbons which are between 4 to 12 carbon atoms per molecule (C4 - C12). It is majorly has the mixture of paraffins (which are alkanes), cycloalkanes (which are naphthenes), and olefins (which are alkenes). So, it will be correct to assign the term mixture to gasoline.

Answer 4) Kerosene - It is a mixture. Kerosene is made up of mixture of hydrocarbons. The chemical composition mainly depends on its source, but it usually consists of about ten different hydrocarbons, where each contains ten to sixteen carbon atoms per molecule. Therefore, assigning kerosene as a mixture is correct.

Answer 5) $O_{2}$ - It is an element. The molecular formula of oxygen is $O_{2}$. Which states that when found in diatomic state the oxygen is stable and can exist freely in nature. The elemental form of oxygen is in the diatomic form. Therefore, oxygen ( $O_{2}$) is an element.

Answer 2

We identify these substances as follows:

Butane - compound
It has a chemical formula C4H10. It consists of 14 atoms - 4 atoms of carbon and 10 atoms of hydrogen. These are being bonded to form a molecule which makes it a compound.

Benzene - compound
It has a formula C6H6. It has 6 atoms of carbon and 6 atoms of hydrogen that are bonded together to form a molecule. Thus, it is a compound.

gasoline - mixture
It consists of different substances or compounds which makes it a mixture of those substances.

kerosene - mixture
It consists of different substances especially hydrocarbons.

O2 - compound
It consists of 2 oxygen atoms which are covalently bonded forming a molecule thus it is a compound