Question

Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (a) air, (b) tomato juice, (c) iodine crystals, (d) sand.

Short answer

(a) Air is a homogeneous mixture, (b) tomato juice is a homogeneous mixture, (c) iodine crystals are a pure substance, and (d) sand is a heterogeneous mixture.

Step-by-step solution

Classify air as a pure substance or a mixture

Air is a combination of multiple gases like nitrogen, oxygen, carbon dioxide, and other trace gases. Since it is made up of more than one component, air is a mixture.

Determine the type of mixture air is

In a homogeneous mixture, the components are uniformly distributed throughout the mixture. In a heterogeneous mixture, the components are not evenly distributed. Since the gases in the air are uniformly distributed, air can be classified as a homogeneous mixture.

Classify tomato juice as a pure substance or a mixture

tomato juice consists of water, tomato pulp, and other ingredients like sugars, acids, and vitamins. As it is made up of multiple compounds, tomato juice is a mixture.

Determine the type of mixture tomato juice is

In tomato juice, the various components are uniformly mixed together, making it difficult to observe individual components. Therefore, tomato juice can be classified as a homogeneous mixture.

Classify iodine crystals as a pure substance or a mixture

Iodine crystals are made up solely of iodine molecules. As it consists of only one type of element, iodine crystals can be classified as a pure substance.

Classify sand as a pure substance or a mixture

Sand is made up of multiple components like quartz grains, feldspar, and other mineral particles. Since it contains different components, sand can be considered a mixture.

Determine the type of mixture sand is

In sand, the various components are not uniformly distributed. You can observe the individual grains and particles that make up sand. Therefore, sand can be classified as a heterogeneous mixture. In conclusion: - Air is a homogeneous mixture - Tomato juice is a homogeneous mixture - Iodine crystals are a pure substance - Sand is a heterogeneous mixture