What is a mixture?

What is a mixture?

• A. Two or more pure substances that are combined physically but not chemically.
• B. A pure substance with a single type of particle
• C. A substance with uniform composition
• D. A substance that cannot be separated

Answer: (A)

Mixtures form when two or more pure substances are combined physically rather than chemically. Each component keeps its own identity and properties, and no new chemical bonds are created. Because the components aren’t chemically bonded, they can usually be separated again by physical methods such as filtration, distillation, or evaporation. That’s why describing a mixture as two or more pure substances combined physically but not chemically fits best. A pure substance, by contrast, contains only one type of particle (an element or a compound). The idea of uniform composition could apply to either a pure substance or a homogeneous mixture, so it doesn’t uniquely define a mixture. And the notion that a mixture cannot be separated is incorrect because physical separation is a hallmark of mixtures.

Mixtures form when two or more pure substances are combined physically rather than chemically. Each component keeps its own identity and properties, and no new chemical bonds are created. Because the components aren’t chemically bonded, they can usually be separated again by physical methods such as filtration, distillation, or evaporation. That’s why describing a mixture as two or more pure substances combined physically but not chemically fits best. A pure substance, by contrast, contains only one type of particle (an element or a compound). The idea of uniform composition could apply to either a pure substance or a homogeneous mixture, so it doesn’t uniquely define a mixture. And the notion that a mixture cannot be separated is incorrect because physical separation is a hallmark of mixtures.