Dry ice is pure. Pure substance refers to a substance composed of a single substance or a compound with fixed physical and chemical properties. Because dry ice is compressed by carbon dioxide at low temperature, and its composition is only carbon dioxide, dry ice belongs to pure substance. The difference between pure substance and mixture pure substance refers to a substance composed of a single substance or compound, which can be expressed by a chemical formula and has a special chemical symbol.
A mixture is a mixture of two or more substances, each of which maintains its original properties.
Pure substances have fixed physical and chemical properties, such as fixed boiling point and melting point, while mixtures have no fixed properties and composition. （GanBingShiChunJingWuHaiShiHunGeWu）