Which of the following would you characterize as pure or nearly pure substance? (a) stomach acid; (b) dry ice; (c) ice-cream; (d) stainless steel; (e) petroleum; (f) distilled water; (g) carbon monoxide gas; (h) compressed air in balloon.

Key Concepts

Pure Substances vs. Mixtures

A pure substance consists of a single type of particle and has a uniform composition and distinct properties. In contrast, mixtures contain two or more different substances that retain their individual properties. Understanding this distinction is crucial for identifying which options in the question are pure substances.

Chemical Composition

The chemical composition of a substance refers to the types and ratios of atoms that make it up. For example, distilled water (H2O) is a pure substance with a specific chemical formula, while mixtures like ice cream contain various components that can vary in proportion. Recognizing the chemical composition helps in determining purity.

State of Matter

The state of matter (solid, liquid, gas) can influence whether a substance is considered pure. For instance, dry ice (solid CO2) and carbon monoxide gas (CO) are both pure substances in their respective states. Understanding the state of matter aids in evaluating the options presented in the question.